Transport Health Assessment Tool for Melbourne (THAT-Melbourne) - Technical Report - Australian Urban Observatory

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Transport Health Assessment Tool for Melbourne (THAT-Melbourne) - Technical Report - Australian Urban Observatory
Technical Report

Transport Health
Assessment Tool
 for Melbourne

(THAT-Melbourne)
   Belen Zapata-Diomedi1,
    Ali Abbas2, Lucy Gunn1,
          Alan Both1
Transport Health Assessment Tool for Melbourne (THAT-Melbourne) - Technical Report - Australian Urban Observatory
THAT-Melbourne — Contents
     Acknowledgements                                                                          Contents
     The team gratefully acknowledges            Enquiries regarding
     the funding from the RMIT University’s      this report may be
     Enabling Capability Platform Opportunity    directed to:
     Fund for Research and Impact and the                                                      01 Introduction	              04
     support of our project partners from
     the State Government of Victoria at
                                                 Centre for Urban Research
     the Department of Transport. We further
     acknowledge the Centre for Urban                                                          02 Scenarios		                06
                                                 Building 8, Level 11
     Research and the Urban Futures              RMIT University
     Enabling Capability Platform at RMIT        City Campus
     University and the Australian Prevention    124 La Trobe Street                           03 Methods	                   08
     Partnership Centre.                         Melbourne VIC, 3000
                                                 Australia
     We acknowledge the technical                                                              03.1 Overview	                08
     contributions from the Public Health        E belen.zapata-diomedi@rmit.edu.au
     Modelling Team at MRC Epidemiology                                                        03.2 Micro-simulation	        09
     Unit at the University of Cambridge. The    P 03 9925 4577
     contributions of Dr Ali Abbas were funded                                                 03.3 Macro-simulation	        14
     by the European Research Council under
                                                                                               03.4 Assumptions	             19
     the Horizon 2020 research and innovation
     program (grant agreement No 817754)                                                       03.5 Uncertainty intervals	   19
     under the GLASST: Global and local health
     impact assessment of transport projects.

     Dr Belen Zapata-Diomedi was funded                                                        04 References	                20
     by a RMIT University Vice-Chancellor’s
                                                 Cover Footnotes
     Postdoctoral Fellowship with some
                                                 1. Healthy Liveable Cities Group,
     components of the code development
                                                 Centre for Urban Research, RMIT University
     completed during her placement at
     the MRC Epidemiology Unit, University       2. UKCRC Centre for Diet and Activity
     of Cambridge under the supervision          Research, MRC Epidemiology Unit, University
     of Dr James Woodcock.                       of Cambridge, Cambridge, UK

     The Transport Health Assessment Tool
     for Melbourne can be accessed in the
     Australian Urban Observatory at auo.
     org.au/transport-health-assessment

02                                                                                                                                  03
Transport Health Assessment Tool for Melbourne (THAT-Melbourne) - Technical Report - Australian Urban Observatory
THAT-Melbourne — Introduction
       01

     Introduction

     The model that forms the basis of the Transport Health
     Assessment Tool for Melbourne (THAT-Melbourne)
     quantifies physical activity-related health impacts arising                                  Under 1km                                        1-2km                                             3-5km
     from a range of scenarios where short car trips are
                                                                                                  100%                                             100%                                              100%
     replaced by walking, cycling or a combination of both,
     based on data from metropolitan Melbourne.                                                                                 82%                                                                                80%

                                                                                                  75%                                              75%                                               75%
     It is well known that physical activity           population (18 years of age and older)
     improves health and reduces the                   not meeting the National Physical
                                                                                                                                                                 52%
     burden of diseases associated with                Activity Guidelines.
                                                                                                  50%                                              50%                            40%                50%
     inactivity and sedentary behaviour. In
     Australia in 2015, physical inactivity            In Melbourne (Figure 1), a small
     contributed to 20% of the disease                 proportion of trips were made by
     burden (mortality and morbidity)                  active modes (walking and cycling)         25%                                              25%                                               25%
                                                                                                               15%
     from diabetes, some types of cancer               compared to the use of private cars
                                                                                                                                                                                                                          11%
     (bowel, uterine, breast), dementia                (Figure 2, Analysis of VISTA survey data                                                                        5%                                                            7%
                                                       [2]). Replacing short car trips of up to                       1%   1%          1%                                    2%          1%                                     2%        1%
     and cardiovascular diseases.[1]                                                              0%                                               0%                                                0%
                                                       10kms by walking and cycling would
     Overall, physical inactivity was                  contribute greatly to increasing
     responsible for 2.5% of the total                 population levels of physical activity
     disease burden with 55% of the adult              and reduce the burden of diseases.
                                                                                                  6-10km                                           Above 10km                                                   Key

                                                                                                  100%                                             100%
                                                                                                               84%                                               86%
     Other              0.7%
                                                                                                                                                                                                                    Car
                                                                                                  75%                                              75%

     Bicycle             1.3%                                                                                                                                                                                       Public Transport

                                                                                                  50%                                              50%
                                                                                                                                                                                                                    Bicycle
     Public                     8.4%
     Transport
                                                                                                  25%                                              25%                                                              Walking
                                                                                                                     13%                                               12%
     Walking                                       26.7%
                                                                                                                           2%    1% 0%                                       1% 0% 1%                               Other
                                                                                                  0%                                               0%

     Car                                                                             63%

     Figure 1: Transport mode share for Melbourne                                                 Figure 2: Transport mode share by distance category for Melbourne
     Source: Analysis of the Victorian Integrated Survey of Travel and Activity (VISTA)           Source: Analysis of the Victorian Integrated Survey of Travel and Activity (VISTA) 2017-18. Analysis conducted on trip stages.
     2017-18. Analysis conducted on trip stages.

04                                                                                                                                                                                                                                              05
Transport Health Assessment Tool for Melbourne (THAT-Melbourne) - Technical Report - Australian Urban Observatory
THAT-Melbourne —Scenarios
      02

     Scenarios                                                                              Table 1: User inputs for the scenarios

     The Transport Health Assessment Tool for Melbourne                                     User Input                      Options
     allows users to choose from a variety of scenarios
     for replacing short car trips with walking, cycling or a                               Trip purpose
     combination of both, accommodating options for trip
                                                                                             All                            Work-related, education, leisure, shopping, pick-up or drop-off someone/
     purpose; age groups; and sex (Table 1).
                                                                                                                            something, personal business, other, accompany someone, at or go home

     The maximum possible distance to          Trip purposes were grouped into:
                                                                                             Commuting                      Work-related and education
     be replaced is 2 kms for walking and      1: all trips, which includes work-related,
     10 kms for cycling. Note that distances   education, leisure, shopping,
     replaced correspond to stages of a        pick-up or drop-off someone/                 Replace car trips with
     trip, for example, a trip to work may     something, personal business,
     include multiple stages including         other, accompany someone,
     walking to a train station, the train     and at or going home;                         Walking                        0 - 1km
     ride itself, and walking from the
                                                                                                                            0 - 2km
     station to the place of employment.       2: commuting, which includes
                                               work-related and education trips.
                                                                                             Cycling                        0 - 2km

                                                                                                                            0 - 5km

                                                                                                                            0 - 10km

                                                                                             Both walking and cycling:      Walking trips 0 - 1km, cycling trips between 1 - 2km

                                                                                                                            Walking trips 0 - 1km, cycling trips between 1 - 5km

                                                                                                                            Walking trips 0 - 1km, cycling trips between 1 - 10km

                                                                                                                            Walking trips 0 - 2km, cycling trips between 2 - 5km

                                                                                                                            Walking trips 0 - 2km, cycling trips between 2 - 10km

                                                                                             Sex                            All

                                                                                                                            Male

                                                                                                                            Female

                                                                                             Age                            16 - 19 years

                                                                                                                            20 - 39 years

                                                                                                                            40 - 64 years

                                                                                                                            65 plus years

                                                                                                                            All age groups

06                                                                                                                                                                                                      07
Transport Health Assessment Tool for Melbourne (THAT-Melbourne) - Technical Report - Australian Urban Observatory
THAT-Melbourne — Methods
      03

     Methods

     03.1 Overview

     The modelling framework is depicted in Figure 3.
                                                                                                                                                 Micro-simulation                                          Macro-simulation                      Outcomes
     The model consists                         We refer to this as the disease           The PMSLT for physical activity was
     of three main sections:                    process in the macro-level simulation.    originally developed for the Assessing
                                                Incidence is the number of new cases      the Cost-Effectiveness in Prevention
     1. Scenarios;                              of disease over a time period and         project (ACE-prevention).[4] The              Scenario                                     Age & sex                                               Cause-specific cases
                                                                                                                                                                                                                                             of diseases prevented
                                                changes in incidence impact on the        version used here also borrows from
     2. Potential Impact
                                                number of people living with a            developments for the Integrated                     Cycling       Physical activity                                                                Cause-specific
     Fractions (PIF); and
                                                disease in later years (prevalence),      Transport Health Impact Model (ITHIM)                                                                                                              deaths prevented
     3. Proportional multi-state                quality of life and mortality.            [5, 27] originally developed for the
                                                                                          United Kingdom with later                     Car                               PIFs          PIFs                Disease process
     life table (PMSLT).
                                                Overall changes in quality of life and    adaptations used in other locations
                                                mortality from all included diseases                                                                                                                                                         Life years
     We developed a hybrid model                                                          including United States, Canada and
                                                are measured within the macro-                                                                Walking        Relative risks                                 Life table
     [3], where the scenarios and PIF                                                     Brazil (https://www.mrc-epid.cam.ac.                                                                                                               Health-adjusted
     calculations are at the individual level   simulation via the life table, which is   uk/research/research-areas/public-                                                                                                                 life years
     (micro-simulation) and the PMSLT           discussed in the sections that follow.    health-modelling/ithim/).
     calculations are at the macro level
                                                The macro-simulation model used           The model was initially developed
     (aggregated by age and sex groups)
                                                was the proportional multi-state life     in Excel and for the version             Figure 3: Analytical framework for the Transport Health Assessment Tool for Melbourne
     (macro-simulation).
                                                table (PMSLT). The model simulates        presented here we used the
     The micro-simulation calculates the        5-year age groups and sex cohorts         statistical computing software
     impact of changes in physical activity     for 1) the base case or business-as-      R. Dr Zapata-Diomedi completed
     due to the scenarios on disease risk       usual scenario; and 2) for the chosen     some components of the code
     at the individual level. Seven diseases    scenario, with baseline year 2017.        development while on placement
     related to physical activity were          PMSLTs for each age and sex cohort        at the MRC Epidemiology Unit,            03.2 Micro-simulation
     included: ischemic heart disease,          are simulated for the base case and       University of Cambridge under the
                                                scenario, and the difference amongst      supervision of Dr James Woodcock.
     stroke, diabetes mellitus type 2, colon
                                                them is initiated by changes in
                                                                                                                                   Potential Impact Fractions (PIFs) (Equation 1) are calculated using relative risks (RR)
     cancer, lung cancer, and for females
     only: breast and uterine cancers.          incidence in the scenario disease                                                  for the seven aforementioned diseases related to the physical activity risk factor for
     Disease risk measures the probability      processes. The population cohorts                                                  the base case and chosen scenarios.
     of becoming diseased given exposure        within the PMSLT are simulated until
     to a risk factor, such as physical         everyone dies or reaches the age
                                                of 100.                                                                            The methods developed in the                  Marginal METs only consider energy                Equation 1: PIFs calculations
     inactivity. The potential impact
                                                                                                                                   ITHIM-R project were used here.[5]            expended above the resting
     fraction (PIF) measures the                                                                                                                                                                                                   Each individual in the modelled
                                                Estimated outcomes are prevented                                                                                                 metobolic rate.
     proportional change in disease                                                                                                Inputs for the PIFs’ calculations                                                               population has a base case and
                                                new cases of chronic diseases and
     risk when exposure to a risk factor                                                                                           are energy expenditures based                                                                   scenario mMET-hours, where the
                                                mortality, Health-adjusted life years
     changes.                                                                                                                      on individual marginal metabolic                                                                scenario is modified by the additional
                                                (HALYs) and Life Years gained. HALYs
                                                                                                                                                                                 PIFdisease       RR base case       RR scenario   walking or/and cycling attributable
     PIFs for the included diseases were        represent life years adjusted for                                                  equivalent of task per hour (mMET-                         =                  -
                                                                                                                                   hours) per week and disease relative                                                            to the scenario. The derivation of
     estimated at the individual level          a reduction in the quality of life
                                                                                                                                   risks. METs are metabolic equivalent                                 RR base case               mMET-hours and the relative risks
     and the average PIFs by age and            attributable to disability of diseases
                                                                                                                                    of tasks and measure the energy                                                                calculations are explained in the
     sex were used to estimate the effect       and injuries.
                                                                                                                                   expenditure required to carry out                                                               sections that follow.
     of changes in physical activity on
                                                                                                                                   physical activity, expressed as a
     incidence rates for the included
                                                                                                                                   multiple of the resting metabolic
     diseases.
                                                                                                                                   rate.[6]

08                                                                                                                                                                                                                                                                           09
Transport Health Assessment Tool for Melbourne (THAT-Melbourne) - Technical Report - Australian Urban Observatory
THAT-Melbourne —Methods
     mMET-hours                                                                                                                        Table 2: MET scores
     A matched population of individuals        We created a trip file for each of the       In this manner, everyone in the
     was created by matching the                scenarios, which contained base case         matched population had measures           Physical activity                                  mMETs             Description
     Victorian Integrated Survey of Travel      and scenario mode of travel for each         for total time by mode for the base
     and Activity (VISTA) 2017-2018 [2]         trip stage along with base case time         case and scenario. The data is for
                                                                                                                                                                                                            Code 17190 (walking, 2.8 to 3.2 mph, level,
     persons file and the National Health       and distance and scenario time. A trip       one day, and we derived weekly total          Walking for transport                          2.5
                                                                                                                                                                                                            moderate, surface, firm) 1
     Survey (NHS), 2017-18, Basic CURF [7] to   may have up to nine stages. Scenario         travel time and distance by mode
     derive individual base case and            time was derived from the original           by multiplying by 7.
     scenario mMET-hours per week.              stage distance from car trips divided                                                                                                                       Code 1011 (bicycling to and from work, self-selected
                                                                                             mMET-hours per individual in the              Cycling for transport                          5.8
                                                by speed for the replacing mode,                                                                                                                            pace; METs=6.8; mMET=6.8-1) 1
     The matching process is depicted in        either walking or cycling, based on the      matched population for the base
     Figure 4. Sampled individuals from NHS     median speed for each mode across            case and scenario were derived from
                                                                                                                                           Walking for leisure                            2.5               Code 17160 (walking for pleasure) 1
     were randomly allocated to the VISTA       the VISTA sample of 4 (25th & 75th           the sum of the product of hours spent
     persons file based on age, sex,            percentiles, 2.6, 5.12) km per hour for      weekly doing transport walking,
     socio-economic status (SES), whether                                                    transport cycling, vigorous physical          Moderate physical activity                     3.5               See reference [8]
                                                walking and 11 km per hour (25th & 75th
     they walk for transport, whether they      percentiles, 7.4, 15) for cycling.           activity for leisure, moderate physical
     walked at least 2 hours per week for                                                    activity for leisure and walking for          Vigorous physical activity                     7                 See reference [8]
     transport and whether they worked.         We created time variables for each           leisure by their corresponding
     The matching process had a success         person for the base case and                 mMET-hours scores (Table 2).
                                                                                                                                       1
                                                                                                                                           Note: Codes relate to METs from the Compendium of physical activities, see reference [9].
     rate of nearly 99%, which implies that     scenario by adding up the time
     only 1% of the VISTA persons had no        for all stages by mode in a trip and
     matching physical activity (PA)            appending them to the matched
                                                                                                                                       Transport walking time in the matched             Hence, we compared results for                  In the matched population the
     variables from the NHS.                    population.
                                                                                                                                       population was derived from                       the mean overall and per time                   mean hours spent in transport
                                                                                                                                       multiplying one day per week from                 categories to check the accuracy                walking per week for the base case
                                                                                                                                       the VISTA survey by 7, whilst transport           of the walking for transport data in            was 1.12 whilst data from the NHS
                                                                                                                                       walking from the NHS was available                this model (Table 3).                           was relatively close at 1.04.
       Data                   Data                    Generated data                   Matching                                        for the whole week.
       sources                used                    sets to match                    variables

       SEIFA                  SES                                                      Age group                                       Table 3: Comparison of walking for transport between NHS and VISTA datasets.
       INDEX
                              Trips                                                    Sex
                                                      Persons
                                                                                                                                                                           NHS                                                   VISTA - Person file
                                                                                                                           mMET-
       VISTA                  Households              transport                        SES                                 hours
       2017-18                                        (n=7,117)                                                             per        Time category                       Mean                       Frequency                  Mean                     Frequency
                              Persons                                                  Walk for transport (Y/N)            person
                                                      Persons                          Walk min for transport                              0 hours                         0.00                       73%                        0.00                     74%
       NHS 2017-18,           Person                  Leisure and
       Basic CURF                                     work (n=16,370)                  Work status
                              Households                                                                                                   0 - 1 hours                     0.70                       3%                         0.57                     1%

                                                                                                                                           1.1 - 2 hours                   1.91                       8%                         1.40                     3%

     Figure 4: Analytical framework for deriving mMET-hours                                                                                2.1 - 5 hours                   3.39                       11%                        3.30                     13%

                                                                                                                                           5.1 - 10 hours                  7.48                       3%                         6.78                     7%

                                                                                                                                           > 10 hours                      22.20                      1%                         13.11                    1%

                                                                                                                                       The two data sources used to derive the individual mMET-hours are discussed on the following page.

10                                                                                                                                                                                                                                                                                 11
Transport Health Assessment Tool for Melbourne (THAT-Melbourne) - Technical Report - Australian Urban Observatory
THAT-Melbourne — Methods
                                                                                                                               Table 4: National Health Survey variables
     Victorian Integrated                      National Health                          All diseases have a threshold
     Travel and Activity                       Survey (NHS)                             beyond which there are no benefits
                                                                                        from increases in mMETs-hours,
     Survey (VISTA)                            The NHS is a representative sample       except for diabetes [5].               Type of           Definition
     The latest VISTA survey conducted         of Australian adults (aged 15 and
                                                                                                                               activity
     across the period 2017-18 for             above). The data were collected by       These thresholds are 35 mMET-
     Greater Melbourne and Geelong             the Australian Bureau of Statistics      hours for colon, breast and uterine
     was used. Randomly selected               and published as the National            cancers, and ischemic heart             Walking          Must have carried out for at least 10 minutes continuously.
     households were asked to                  Health Survey, 2017-18. A sample of      disease; 10 mMET-hours for lung         for fitness,
     complete the household form with          21,315 adults was available.             cancer and 32 mMET-hours                recreation
     each adult individual required to                                                  for stroke.                             and sport
     complete a travel diary for a single      Survey respondents were asked
     specified day (with an adult              about the time they spent doing          The meta-analysis provided data
                                                                                                                                Walking to       Excludes activities such as walking around      Must have carried out for at least 10
     completing the travel diary for           exercise (for leisure or walking for     for the RRs for each of the diseases
                                                                                                                                get from         a shopping centre as people tend to             minutes continuously.
     children). The survey aims to             transport) and workplace physical        and mMET-hours per week. Hence,
                                                                                                                                place to place   frequently pause while shopping.
     capture average travel behaviour.         activity in the last week. Table 4       each individual in the matched
                                               outlines types of physical activity      population described above has
     The Greater Melbourne survey              data collected in the NHS.               a corresponding RR for the base         Moderate         Comprises activities that caused a              Excludes any previously identified
     included 3,543 households,                                                         case and scenario which are then        intensity        moderate increase in the heart rate or          walking as well as household chores,
     7,117 individuals and 23,166 trips.       Relative risks                           used to calculate the individual        exercise         breathing of the respondent (e.g. gentle        gardening or yard work, and any activity
     Travel data was collected for             physical activity                        level PIFs. Average PIFs for each                        swimming, social tennis, golf).                 carried out as part of a job.
     all individuals aged above 5 in                                                    of the diseases by age and sex
                                               Relative risks (RRs) compare the
     each household.                                                                    modify incidence in the disease
                                               likelihood of an adverse event                                                   Vigorous         Comprises activities that caused a large        Excludes any previously identified
                                                                                        life tables in the PMSLT.
                                               occurring with the likelihood of                                                 intensity        increase in the respondent’s heart rate or      walking as well as household chores,
     We limited the analysis to individuals
                                               the same event not occurring                                                     exercise         breathing (e.g. jogging, cycling, aerobics,     gardening or yard work, and any activity
     aged 16 and above given that the
                                               depending on the level of exposure                                                                competitive tennis).                            carried out as part of a job.
     scenarios consist of replacing car
                                               to a risk factor or protective factor.
     trips and the legal driving age in
     Melbourne commences at age 16                                                                                              Strength         Activities designed to increase muscle          Includes any strengthening and toning
                                               In this model the protective factor is
     under the full supervision of a                                                                                            or toning        strength or tone, such as lifting weights,      exercises or activities already
                                               physical activity. We used the RRs
     licensed driver.                                                                                                           exercises        resistance training, pull-ups, push-ups, or     mentioned.
                                               for physical activity-related
                                                                                                                                                 sit ups.
                                               diseases from the meta-analysis
     The travel diary asked respondents
                                               developed by the University of
     about travel and activities on a
                                               Cambridge Public Health Modelling                                                Workplace        Usual physical activity while at work           Vigorous activity in the workplace was
     particular travel day, specifically: 1)
                                               Group [28] for breast cancer, colon                                              physical         on a typical work day.                          defined as activity that caused a large
     all travel over the whole day, from
                                               cancer, ischemic heart disease,                                                  activity                                                         increase in heart rate or breathing (e.g.
     4:00 am on the travel day until 4:00                                                                                                        Must have carried out for at least
                                               stroke and lung cancer as well as                                                                                                                 carrying or lifting heavy loads, digging
     am the next day, 2) all trips to be                                                                                                         10 minutes continuously.
                                               the RRs reported in reference [8] for                                                                                                             or construction work).
     included, even short trips (like
                                               diabetes, which were derived from                                                                 Moderate activity in the workplace
     walking to lunch or going for a jog).
                                               mortality and incidence combined.                                                                 was defined as activity that caused a
     VISTA also includes people who do
     not travel on the travel survey day.                                                                                                        moderate increase in the heart rate or
                                                                                                                                                 breathing of the respondent (e.g. brisk
                                                                                                                                                 walking or carrying light weights).

12                                                                                                                                                                                                                                              13
THAT-Melbourne — Methods
     03.3 Macro-simulation

     The PMSLT has been used to simulate health impacts of changes in exposure                                                        Figure 5 describes the interaction between life table parameters and disease parameters. All the parameters are age specific denoted with

     to health risk factors for population groups (e.g. age and sex cohorts).                                                         x, i is incidence, p is prevalence and m is mortality, w is a disability adjustment, pyld is prevalent years lived with a disability, q is probability
                                                                                                                                      of dying, l is number of survivors, L is life years, Lw is disability adjusted life years. A change in physical activity translates into changes in
                                                                                                                                      incidence (ix), which changes disease specific prevalence (px) and mortality (mx). For presentation purposes we only depict one disease
     Figure 5 is a schematic representation      mortality are calculated. Transition      The difference between pYLDs and           process, however, in this study we modelled 7 diseases (ischemic heart disease, stroke, breast cancer, colon cancer, type 2 diabetes, uterine
     of the PMSLT. The two PMSLT                 probabilities between states are used     mortality rates between base case          cancer, and lung cancer).
     components are a life table and             in the derivation of incidence to         and scenarios disease processes are
     disease process for each of the             adjust the transition from healthy        collected in the scenario life table to
     modelled diseases.[10]                      to diseased and case fatality from        modify all-cause mortality and pYLD
                                                 disease to dead from the diseases [11]    total. Cohorts in the general life table   PIF type
                                                                                                                                                                                                     -(Prevalencescenario - Prevalencebase case ) * (RR-1)
     These two components are modelled           (see Table 5 for data inputs).            are modelled from the baseline year        2 diabetes                                          PIF =
     for both the base case and scenario                                                   (2017) until they die or reach the age
     for each sex and 5-year age cohorts.        The PIFs by age and sex cohort                                                       Type 2 diabetes is a risk factor for
                                                                                           of 100.
                                                                                                                                      ischemic heart disease and stroke                                             Prevalencebase case * (RR-1) + 1
     The life table models the survival for      explained in sections 3.1 and 3.2
     the cohort and includes for a given         modify incidence in the scenario’s        The health outputs are measured as         [12, 13], hence, we also included the
                                                                                                                                      PIFs for stroke and ischemic heart                  Prevalencescenario represents the prevalence of type 2 diabetes after the scenario, whilst
     age interval the probability of dying,      disease process. Because type 2           the difference between the base case
                                                                                                                                      disease as a function of changes in                 Prevalencebase case represents the prevalence for type 2 diabetes in the base case and
     the number of people alive, life years      diabetes is a risk factor for ischemic    and scenario disease processes and
                                                                                                                                      diabetes as shown in Equation 2 and                 RR represent the relative risk for stroke or ischemic heart disease respectively.
     and the rate of total prevalent years       heart disease and stroke [12, 13], the    life table. The model assumes that
     lived with disability (pYLD total). Total   impact of changes in type 2 diabetes      diseases are independent from one          summarized in Table 5 for males and
     pYLD is the proportion of life that is      due to the scenario are calculated        another (i.e. the probability of           females respectively within the PMSLT.              Equation 2: PIF for diabetes
     lost due to diseases and injury             (see section 3.3.1). Disability weights   developing one disease is unrelated
     (disability) and adjusts life years         (section 3.3.2 Table 5), which reflect    to the probability of developing
     to derive the measure of Health-            the health loss attributable to disease   another) and are independent from
     adjusted life years (HALYs).                on a scale from 0 (perfect health)        all causes of death.[10]
                                                 to 1 (equivalent to death) [14] are
     For each of the seven diseases and          multiplied by disease prevalence to                                                  For ischemic heart disease and
     their disease processes, incidence,
     prevalence and disease specific
                                                 derive disease specific pYLDs.                                                       stroke, we calculated the combined
                                                                                                                                      PIF according to Equation 3 given
                                                                                                                                      that these two diseases have two
                                                                                                                                                                                          PIFcombined
                                                                                                                                                                                                          =
                                                                                                                                                                                                              ∏r
                                                                                                                                                                                                                     1 - (1 - PIFrisk)

                                                                                                                                      risk factors in the model: physical
                                                                                                                                      inactivity and type 2 diabetes:                     Equation 3: Combined PIF
     Disease process base case                                                  PMSLT base case

      ix         px        mx                                                    mx        qx          Ix         Lx
                                                                                                                                      Table 5: Relative risks for the association between diabetes and stroke and ischemic
                                                                                                                               Lwx    heart disease by sex [12, 13]
                 w          pylds                                                                                 pyldx

     Disease process scenario                    Difference between             PMSLT scenario                                                                                      Relative Risk (95% confidence interval)
                                                 scenario and base case

      ix         px        mx                              mx                    mx        qx          Ix         Lx                   Disease                                      Female                                          Male
                                                                                                                               Lwx
                                                                                                                                       Ischemic heart disease                       2.82 (2.35, 3.38)                               2.16 (1.82, 2.56)
                 w          pylds                         pyldx                                                   pyldx

                                                                                                                                       Stroke                                       2.28 (1.93, 2.69)                               1.83 (1.60, 2.08)
     Figure 5: PMSLT analytical framework

14                                                                                                                                                                                                                                                                                                15
THAT-Melbourne — Methods
     Disability weights                                                YLDdisease                 Data inputs                                   Incidence and case fatality
     Disability weights (DW) are derived                                  Pdisease                Data for the proportional multi-state life    We used Australian Institute of Health              We used Dismod II (free at https://               (except for long life sequelae) [23],
     from disease specific prevalent years      DWadjusted                                        table model (PMSLT) include inputs for        and Welfare (AIHW) incidence and                    www.epigear.com/index_files/                      but in our model we assumed no
                                                               =
     lived with disability (YLD) and disease                                                      the life table. Specifically, this includes   mortality cancer data for 2017 for                  dismod_ii.html) to derive internally              remission for diseases. In addition,
                                                                        1-YLDtotal
     specific prevalence by age group (5                                                          inputs for population, mortality rates        Australia and GBD data for Australia                consistent inputs for incidence and               AIHW generates data for colon cancer
     years) and sex. Data for YLDs                                                                and prevalent years lived with disability     for other diseases for the year 2017 to             case fatality and to generate missing             and lung cancer, while the GBD only
     prevalence is from the Global Burden                                                         and rates for all causes (i.e., Years Lived   derive incidence and case fatality                  data. For example, the GBD study                  provides estimates for larger disease
     of Disease (GBD) data for 2017.            Equation 4: DW adjusted                           with Disease or YLD); and, for the            inputs for colon cancer, lung cancer,               provides data for incidence,                      groups (colon and rectum cancer and
                                                                                                  diseases process incidence and case           ischemic heart disease, stroke and                  prevalence and disease mortality,                 tracheal, bronchus, and lung cancer).
     An age and sex specific-correction         Equation 4 Where YLDdisease is the YLD            fatality. Here we prepared inputs for the     type 2 diabetes, and for females                    however, not case fatality.                       Dismod II is a separate tool, therefore,
     was introduced to counteract the           mean number per age and sex for a                 Melbourne population.                         only breast and uterine cancer.                                                                       here, we provide information relating
     effects of accumulating comorbid           given disease, Pdisease is the prevalence                                                                                                           For cancers we used AIHW given                    to any processing of the original
     illnesses in the older age groups as                                                         When local inputs were available, these                                                           that the GBD data was derived
                                                as reported in the Global Burden of                                                                                                                                                                   data (Table 7).
     shown in Equation 4. Interpolation was                                                       were used, otherwise, we used state or                                                            assuming remission for cancers
                                                Disease study for a given disease by
     used to derive rates per single year                                                         nationally representative inputs. Table 5
                                                age and sex and YLDtotal is the total
     of age from 5-year age intervals.                                                            describes all data inputs for the PMSLT.
                                                YLD rate per age and sex.
                                                                                                  Each of the PMSLT components and
                                                                                                                                                Table 7: Disease processing DISMOD II
                                                                                                  related data processing are explained
                                                                                                  below in Table 6.

                                                                                                                                                Disease             Collection data                       Disease inputs                 ICD-10 codes1                 Process
     Table 6: PMSLT data inputs                                                                                                                      Diabetes       Population and                        Incidence, prevalence          E08-E08.11, E08.3-E08.9,      Remission
                                                                                                                                                     mellitus       mortality rates [17].                 and mortality [17].            E12-E12.1, E12.3-E13.11,      set to zero.
                                                                                                                                                     type 2                                                                              E13.3-E14.1, E14.3-E14.9,
     Component Data needs Input data                                                     Data processing                                                                                                                                 R73-R73.9 (all diabetes)

      Life table       Population        Population Greater Melbourne [15]               Population data is from the ABS 2016 Census.                Ischemic       Population and                        Incidence, prevalence          I20-I21.6, I21.9-I25.9,       Remission set to zero
                       numbers and       by 5-year age groups and sex and                Mortality rates are for Victoria given that                 heart          mortality rates [17].                 and mortality [17].            Z82.4-Z82.49                  and higher weight to
                       mortality rates   death rates by single year of age               future projections for mortality were                       disease                                                                                                           prevalence input
                                         and sex [16].                                   available for Victoria and not for Melbourne.                                                                                                                                 (half bar).
                                                                                         Deaths rates projections were available
                                                                                         by 1-year age intervals and sex from 2017                   Stroke         Population and                        Incidence, prevalence          G45-G46.8, I60-I62,           Remission set to zero
                                                                                         (baseline to 2066) based on the medium                                     mortality rates [17].                 and mortality [17].            I62.9-I64, I64.1,             and higher weight to
                                                                                         population growth assumption.                                                                                                                   I65-I69.998                   prevalence input
                                                                                                                                                                                                                                                                       (half bar).

      Life table       All-cause         Global Burden of Disease (GBD) study            GBD data is in five-year age groups,
                                                                                                                                                     Breast         Population (2017) and deaths          Incidence and                  C50                           Remission
                       YLDs              by 5-year age groups and sex [17].              interpolation to derive one-year age group.
                                                                                                                                                     cancer         data (2017) for Australia             mortality [26].                                              set to zero.
                                                                                                                                                     (females)      (Australian Bureau of
      Disease          Disability        Disability weights were derived from            Table 6 outlines DISMOD II data processing                                 Statistics) [24, 25].
      process          weights,          disease specific YLDs [17]. Incidence           and data inputs. Disability weights were
                       incidence and     and case fatality were derived using            calculated by dividing disease specific YLDs                Uterine        Population and deaths                 Incidence and                  C54-C55                       Remission
                       case fatality     DISMOD II software [18].                        by prevalence and adjusted by all cause YLDs.               cancer         data for Australia (Australian        mortality [26].                                              set to zero.
                                                                                                                                                     (females)      Bureau of Statistics) [24, 25].
      Disease          Future trends     Trends in cancers for incidence [19]            Derived from past data when unavailable.
      process          to apply to       and mortality [20]. Trends for                                                                              Colon          Population and deaths                 Incidence and                  C18                           Remission
                       incidence and     cardiovascular diseases and                                                                                 cancer         data for Australia (Australian        mortality [26].                                              set to zero.
                       case fatality     diabetes were not available. These                                                                                         Bureau of Statistics) [24, 25].
                                         were derived from past data [21 -23].
                                                                                                                                                     Lung           Population and deaths                 Incidence and                  C33-C34                       Remission
                                                                                                                                                     cancer         data for Australia (Australian        mortality [26].                                              set to zero.
                                                                                                                                                                    Bureau of Statistics) [24, 25].
                                                                                                                                                1
                                                                                                                                                    Note: ICD-10 codes refer to those from the International Statistical Classification of Diseases and Related Health Problems.

16                                                                                                                                                                                                                                                                                                   17
THAT-Melbourne — Methods
     Diseases’ trends                                                                                                       03.4 Assumptions
     Table 8 outlines methods used to derive diseases’ trends.
                                                                                                                            The PMSLT models the future health trajectories of age and sex cohorts.
                                                                                                                            Trends were applied to diseases’ incidence and all-cause mortality to
     Table 8: Diseases’ trends
                                                                                                                            reflect future changes.

     Input                  Inputs                       Assumptions            Data processing                             However, trends were not applied to     travel patterns in 2017-18 also prevail   observed in those aged 25-29
                                                                                                                            physical activity from the National     in the future. For example, those in      years of age today when they
                                                                                                                            Health Survey and the VISTA survey.     the age cohort 20-24 in 2017              reach that age (by sex).
      Incidence             Australian Institute         Applied to incidence   We derive an annual trend as the log        This implies that we assumed that       (baseline) will have the physical
      cancers               of Health and Welfare        and case fatality.     difference between the age                  the reported physical activity and      activity and travel patterns
                            [20] forecast from 2017                             standardized rate in 2020 and 2017
                            to 2020.                                            divided by the difference in years.

      Case fatality         Australian Institute         Applied to incidence   See above.
      cancers               of Health and Welfare        and case fatality.
                            [20] forecast from 2014
                            to 2020 for mortality.
                                                                                                                            03.5 Uncertainty intervals
      Cardiovascular        Australian Institute         Applied to incidence   Future Age standardized rates (ASR)
      diseases              of Health and Welfare        and case fatality.     were first derived from ASR from past       Ninety-five percent uncertainty intervals [6] were determined for all
                            [22] hospitalization past    Trends were applied    trends by sex using linear regression for
      incidence                                                                                                             outcome measures by Monte Carlo simulation (1000 iterations) (Table 9).
                            trends (actual data)         to ischemic heart      predominantly increasing trends and
                            from years 2001 to 2018.     disease and stroke.    log-linear regression for decreasing
                                                                                trends. Trends were estimated up to year    Intervals were derived for the          These intervals indicate the degree
                                                                                2023. Annual trends were derived as         2.5% and 97.5% percentiles of           of uncertainty for the parameters
                                                                                above (ln(ASR2023/ASR2018)/years).          the simulation results.                 estimated in the model given the
                                                                                                                                                                    input data.
      Cardiovascular        Australian Institute         See above.             Future Age standardized rates (ASR)
      diseases case         of Health and Welfare                               were first derived from ASR from past
      fatality              [22] mortality past trends                          trends by sex using linear regression for   Table 9: Distributions for Monte Carlo simulation
                            (actual data) from                                  predominantly increasing trends and
                            years 2001 to 2018.                                 log-linear regression for decreasing
                                                                                trends. Trends were estimated up to
                                                                                year 2023. Annual trends were derived       Inputs                 Uncertainty/Parameters                          Source
                                                                                as above (ln(ASR2023/ASR2018)/years).
                                                                                                                             Relative risks        Sample from normal distribution, defined        https://shiny.mrc-epid.cam.ac.uk/
                                                                                                                             physical activity     by the mean and standard deviation              meta-analyses-physical-activity/
      Diabetes              Australian Institute of      Trends only applied    Same as above with forecast
                                                                                                                                                   derived from the difference between the
      incidence             Health and Welfare [23]      to incidence.          up to year 2023.
                                                                                                                                                   upper and lower bound divided by 1.96,
                            mortality past trends
                                                                                                                                                   truncated to 0.
                            from years 1997 to 2023
                            for diabetes as the
                            underlying or associated                                                                         Relative risks        Log-normal, see table 4.                        See table 4.
                            cause of death.                                                                                  diabetes

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THAT-Melbourne — References
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