THE SURF REPORT 1 SURVEILLANCE OF RISK FACTORS RELATED TO NONCOMMUNICABLE DISEASES: CURRENT STATUS OF GLOBAL DATA

 
THE SURF REPORT 1 SURVEILLANCE OF RISK FACTORS RELATED TO NONCOMMUNICABLE DISEASES: CURRENT STATUS OF GLOBAL DATA
The SuRF Report 1
Surveillance of Risk Factors
related to noncommunicable diseases:

Current status of global data

Noncommunicable Diseases and Mental Health
World Health Organization
20 Avenue Appia
1211 Geneva 27
Switzerland

              World Health
              Organization
WHO Library Cataloguing-in-Publication Data
    The SuRF report 1. Surveillance of risk factors related to noncommunicable diseases:
    current status of global data.
               (SuRF reports)
    1.Chronic disease – epidemiology 2.Risk factors 3.Epidemiologic surveillance 4.Databases,
    Factual 5.Data collection – methods I.WHO Global NCD InfoBase Team II.Title: Surveillance of risk
    factors related to noncommunicable diseases: current status of global data.
    ISBN 92 4 158030 5                                       (NLM Classification: WT 500)

    Acknowledgements
    The World Health Organization wishes to acknowledge the support from the Governments
    of Australia, Canada, the Netherlands, Sweden and the United Kingdom towards the development of
    the WHO Global NCD InfoBase. The World Heart Federation provided additional support.

    Invaluable contributions towards the development of the InfoBase, from which country
    profiles for the Surveillance of Risk Factors (SuRF) report have been drawn, have also
    been received from many organizations, institutions and individuals that are listed in
    the Acknowledgements section of the accompanying CD-ROM. The authors would like
    to acknowledge Dr Andreas Wielgosz and Dr Hongbo Liang at the WHO Collaborating Centre
    at the University of Ottawa. Their initial work on the CVD InfoBase was a precursor for the WHO
    Global NCD InfoBase. Technical support on internal WHO data bases was provided
    by Dr Chizuru Nishida (BMI data base), Emmanuel Guindon and Omar Shafey (NATIONS data base),
    and Dr Nina Rehn (Alcohol data base). Dr Sylvia Robles and colleagues in PAHO kindly allowed the use
    of the acronym, SuRF.

    Dr Kate Strong leads a team at HQ which has included the following: Ms Maria Filimonenko, Dr
    Hongbo Liang, Ms Jaclynn Lippe, Ms Carina Marquez, Mr Sean McGrath, Ms Angela Newill, Ms Tomoko
    Ono, Ms Rachel Pedersen and Ms Yin Mun Tham. Support and co ordination in the Regional Offices
    was provided by Dr Krishnan Anand (SEAR), Dr Maximillian de Courten (WPRO), Dr Djohar Hannoun
    (AFRO), Mr John Jabbour (EMRO), Dr Paz Rodriguez (AMRO) and Dr Aushra Shatchkute (EURO).

    Copies can be obtained from:
    Email: ncdsurf@who.int – Fax: +41 22 791 4769,
    The content of the SuRF report is available on the Internet at:
    http://www.who.int/ncd/surveillance/surveillance_publications.htm

    Suggested citation: Strong K, Bonita R. The SuRF Report 1. Surveillance of Risk Factors related to
    Noncommunicable Diseases: Current status of global data. Geneva, World Health Organization, 2003.

    © World Health Organization 2003
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2
Contents
                      Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .   4
                      Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .       5

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .                    6
                      WHO Global NCD InfoBase . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .                 7

Methods               ..................................................................                                                                            9
                      Contents of the SuRF report . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .                 9
                      Population data and average life expectancy
                      Statistical methods
                      Risk factors
                      WHO’s approach to risk

                      Risk Factor methodology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
                      Tobacco use
                      Alcohol consumption
                      Physical inactivity
                      Fruit and vegetable intake
                      Obesity and overweight
                      Raised blood pressure
                      Raised blood lipids
                      Diabetes

Data Sources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
                      Country-level sources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
                      European Region
                      Region of the Americas
                      South-East Asia Region and Western Pacific Region
                      Eastern Mediterranean Region
                      African Region
                      Additional survey instruments
                      Gaps and deficiencies in data

                      WHO’s response to addressing the gaps in risk factor data . . . . . . . . . . . . . . . . . . . . . . . . 22

The WHO Global NCD Infobase . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
                      Structure of the InfoBase . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
                      Source
                      Survey methods
                      Data entry
                      Selecting data for display
                      Displaying data in SuRF report format

                      Using the country profiles on CD-ROM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
                      Future additions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

Vision for the future . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
References            . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Appendices            . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
                      Appendix 1: Acronyms and abbreviations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
                      Appendix 2: Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
                      Appendix 3: Six tables for Regional Offices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
                                                                                                                                                                        3
Preface
    Until recently, risk factors such as raised blood pressure, cholesterol, tobacco use, excess
    alcohol consumption, obesity, and the diseases linked to them, were more commonly asso-
    ciated with developed countries. However, the World Health Report 2002: reducing risks,
    promoting healthy life, indicates that they are now becoming more prevalent in developing
    nations. These countries are being affected by a double burden of disease, the combination
    of long-established infectious diseases and the rapidly growing epidemic of chronic, non-
    communicable diseases (NCDs). WHO has responded by giving higher priority to NCD pre-
    vention, control and surveillance in its programme of work. Now more than ever, standard
    methods and tools are needed to enable countries to build and strengthen their capacity to
    conduct surveillance of NCDs and their risk factors.

    One such tool is the WHO STEPwise approach to Surveillance (STEPS) of risk factors relat-
    ed to NCDs. It is a simplified, stepwise approach providing standardized materials and
    methods to help countries, especially those that lack resources, initiate NCD activities. The
    goal is to achieve data comparability between countries over time.

    The SuRF Report 1 introduces another tool, the WHO Global NCD InfoBase, which assem-
    bles, for the first time in one place, NCD risk factor data collected from WHO Member
    States. Data from the InfoBase is presented in the country profiles of the SuRF report and
    its associated CD-ROM attachment. Displaying the currently available data is the first step
    towards improving NCD risk factor data collections. This is an on-going process. In the next
    step (SuRF 2), the available country data will be used to produce comparable estimates for
    risk factor prevalence in WHO Member States. This will result in an advocacy tool with the
    power to transform health policy by highlighting the need for primary prevention and health
    promotion.

              Ruth Bonita,                                               Derek Yach,
          Director Surveillance                                       Executive Director

                          Noncommunicable Diseases and Mental Health
                                 World Health Organization

4
Summary
High quality health statistics are essential for planning and implementing health policy in
all country settings. In fact noncommunicable disease (NCD) risk factor data are crucial for
predicting the future burden of chronic disease in populations and also for identifying
potential interventions to reduce the future burden. The Surveillance of Risk Factors report
(SuRF) presents, for the first time, country-level NCD risk factor prevalence data from the
WHO Member States.

– The focus of the report is on recent, nationally representative data.
– The risk factors of choice are those that make the greatest contribution to mortality and
  morbidity from chronic disease, can be changed through primary intervention and are
  easily measured in populations.
– Eight risk factors that relate mainly to cardiovascular disease fit this criteria: tobacco
  and alcohol use, patterns of physical inactivity, low fruit/vegetable intake, obesity (as
  measured by BMI), blood pressure, cholesterol and diabetes (measured by blood glu-
  cose).
– Of principal importance to the data collection is the need to display prevalence data and
  (where possible) mean values for these 8 risk factors by age group(s) and sex and with
  some measure of the uncertainty of the estimates for each Member State.

NCD risk factor information included in the SuRF report comes from a variety of sources,
ranging from peer-reviewed journal articles to reports and unpublished data from Ministries
of Health. All of this information is held in the WHO Global NCD InfoBase, designed as a
“one stop” resource for data needs. The NCD InfoBase is a timely tool for collecting and
displaying current country-level NCD risk factor data and was used to create the country
profiles of risk factor data displayed on the CD-ROM attachment to this report.

Much of the data gathered for the country profiles has been provided by data focal points
in WHO Regional Offices. Plans are in place to develop Regional NCD InfoBases to improve
the country coverage for data on NCDs and their risk factors.

The format of SuRF 1 consists of a report booklet and CD-ROM attachment. It is the first
step in a series of SuRF reports and presents current country data that are largely non
comparable. The second step will be to produce harmonized prevalence estimates from the
existing country data. These comparable estimates will become a powerful tool in advocat-
ing for primary prevention and health promotion. SuRF 1 will be followed by an interactive
website in the autumn of 2003.

                                                                                               5
Introduction
    The report on the Surveillance of Risk Factors (SuRF) assembles, for the first time, existing
    data on the prevalence of the major risk factors related to noncommunicable diseases
    (NCDs) for WHO Member States. It focuses on recent, nationally representative data and
    presents the data as they are reported by survey sources. The risk factors included in the
    report are those that:
    – contribute the most to mortality and morbidity from chronic diseases;
    – can be changed through primary intervention; and
    – can easily be measured in populations.

    The eight risk factors that fit this criteria are tobacco and alcohol use, patterns of physical
    inactivity, low fruit/vegetable intake, obesity, raised blood pressure, raised cholesterol and
    diabetes. It is important for the data collection to display prevalence and/or mean values
    for these eight risk factors by age and sex, and with some measure of the uncertainty for
    each estimate.

    Knowledge of noncommunicable disease (NCD) risk factors is important for predicting the
    burden of chronic disease in populations and for identifying potential interventions to
    reduce such burdens. The World Health Report 2002: Reducing risks, promoting healthy
    life highlights the importance of risk factors as indicators of future health status (WHO,
    2002). Even in the poorest countries, NCD risk factors such as raised blood pressure, cho-
    lesterol and tobacco use are responsible for increasing levels of chronic diseases and pre-
    mature deaths. In fact, the joint effects of these three risk factors account for 65% of all
    cardiovascular diseases in those above the age of 30 (WHO, 2002). Furthermore, five of
    the top 10 global risks to health are NCD risk factors (Table 1). These include raised blood
    pressure, tobacco use, alcohol consumption, cholesterol and obesity/overweight.

    Table 1 Leading 10 selected risk factors as selected causes of disease burden (World Health Report 2002).
            Indicates major NCD Risk Factors.

     Developing Countries                                                 Developed Countries

     HIGH MORTALITY                  LOW MORTALITY

      1. Underweight                 Alcohol                              Tobacco use

      2. Unsafe sex                  Blood pressure                       Blood pressure

      3. Unsafe water                Tobacco use                          Alcohol

      4. Indoor Smoke                Underweight                          Cholesterol

      5. Zinc deficiency             High body mass index                 High body mass index

      6. Iron deficiency             Cholesterol                          Low fruit and vegetable intake

      7. Vitamin A deficiency        Low fruit and vegetable intake       Physical inactivity

      8. Blood pressure              Indoor smoke                         Illicit drugs

      9. Tobacco use                 Iron deficiency                      Unsafe sex

     10. Cholesterol                 Unsafe water                         Iron deficiency

6
Unfortunately, country-level data on common, measurable NCD risk factors are scarce. Few
countries have the resources, infrastructure or political commitment to collect this type of
information in a sustainable manner. While some developed countries have regular national
health surveys that include selected NCD risk factors, others gather their information
through small, costly ad hoc surveys. The objective of this report is to promote the sustain-
able collection of high quality risk factor data and to advocate establishing surveillance
systems for noncommunicable diseases and their risk factors as an alternative to costly ad
hoc surveys.

The risk factor prevalence profiles help to identify a country’s strengths as well as gaps and
deficiencies in its data. Where possible mean values for systolic blood pressure, total cho-       The risk factor preva-
lesterol, blood glucose and body mass index have been included to describe the distribu-
tion of the risk factors in specific populations. The World Health Report 2002 demon-              lence profiles help to
strates that NCD risk factors contribute significantly to the burden of disease in both            identify a country’s
developed and developing countries. Now is the time to assess the quality of NCD risk fac-
tor information at the country-level so that this information can be improved and/or               strengths as well as
expanded to provide the impetus for better health policy.                                          gaps and deficiencies
Valid and reliable health statistics are essential for planning and implementing health poli-      in its data.
cy in all settings. The first step is to identify and assess the quality of NCD risk factor data
collected globally. The SuRF report takes this first step and attempts to identify the most
recent prevalence estimates for risk factors related primarily to cardiovascular disease.
Some important country data may be missing by the time this document is published but
country data collection is ongoing and additional information will be reflected in future
SuRF reports.

A main objective of the NCD surveillance programme is to use the collected country data
to produce best estimates of country-level risk factor prevalence and trends in standard age
groupings. The resulting comparable risk factor estimates will be published in the SuRF
report 2. To help make country data accessible and comparable, data is being collected
and stored in a data base, the WHO Global NCD InfoBase.

WHO Global NCD InfoBase
The risk factor data displayed by the SuRF report come from the WHO Global NCD
InfoBase. The InfoBase collects all, current country-level data on important NCD risk fac-
tors for all WHO Member States. There are many different survey instruments available for
collecting data on health behaviours and physical measurements of risk exposure. Each
instrument has advantages and limitations. For example, some countries have nationally
representative surveys with good sampling frames and well defined methodology. In these
cases, the most recent national survey represents the best estimate of risk factor preva-
lence for that country.

In other countries, where there is little data, surveys may be non-representative of the
national population, include non-probability sampling frames or have other limitations
reflected in the survey methodology. However, such surveys can still be used, taking into
account their limitations, to help build a model to estimate risk factor prevalence for a
country. Understanding the strengths and deficiencies of the data allows users to maximize
the use of the existing information for health policy and research purposes.

                                                                                                   7
The NCD InfoBase displays all the surveys that a country has with information about survey
                         design and representativeness and gives users the opportunity to select the surveys that
                         they wish to display. In addition, the InfoBase contains risk factor prevalence data from
                         other WHO in-house data bases, including the NATIONS tobacco database, the WHO
                         Global BMI database and the WHO Global Alcohol database. The InfoBase has a flexible
                         data base structure to allow the inclusion of disease-specific modules in the future. Data
                         on stroke and respiratory diseases are currently being included, as are measures of oral
                         health. Indicators of injury and violence will be included in the future. A detailed account
                         of the structure of the InfoBase is given in Section 4.

  Understanding the      The NCD InfoBase will be available on the internet towards the end of 2003. This tool for
                         identifying country-level data and assessing its validity provides a starting point for making
 strengths and defi-     NCD risk factor data comparable. Displaying the available data in one place is the first
ciencies of the data     step towards developing better quality NCD data collections.

        allows users     The data presented in this report are by no means complete and require continuing contact
                         with Ministries of Health and study authors. The SuRF report and the NCD InfoBase will be
to maximize the use      up-dated and published regularly with assistance from data focal points in all six WHO
of the existing infor-   regional offices.

   mation for health
 policy and research
           purposes.

                     8
Methods
This section explains some of the concepts that inform the selection and presentation of
NCD risk factors in the SuRF report. The report is made up of a brief text section and a
CD-ROM containing a copy of the text section and complete country profiles of NCD risk
factor data for WHO Member States.

In addition, a list of abbreviations used in the country profiles and throughout the text is pro-
vided at the beginning of this report. A glossary is also included to explain frequently used
terms. The CD-ROM includes a complete bibliography of the SuRF report country profiles
and an extensive acknowledgement section to thank all who helped to provide country data.

Contents of the SuRF report
The advantage of the SuRF report is that it displays country risk factor profiles on CD-ROM
to make the data more accessible. The CD-ROM format enables direct access to the data
on a computer instead of a unwieldy paper copy. The format displays the following informa-
tion for each Member State:
– all recent risk factor data;
– age-specific prevalence rates or mean values;
– survey sample sizes;
– 95% confidence intervals;
– risk factor definitions; and
– complete source information.

In many cases, study authors or Ministries of Health have been contacted for additional,
unpublished information about their risk factor surveys. Notes attached to the source refer-
ence indicate where additional information has been provided and identifies the provider.

The SuRF report is a product of the NCD surveillance activities which follow a STEPwise
approach. The first step is an ongoing project to provide up-to-date country data on NCD
risk factors. The second step will use the acquired country data to produce comparable
best estimates of country risk factor prevalence in standard age groupings. The third step is
to use these comparable estimates to advocate for an improved policy response to the
growing global burden of chronic disease.

Population data and average life expectancy

Each country profile is identified by the official name of the Member State, the WHO region to
which it belongs and general information about its population size and average life expectancy
(Figure 1). Estimates of 2002 population size and age structure are based on the 2000
and 2001 demographic assessments prepared by the United Nations Population Division.

Figure 1
                                              Male                  Females

 2002 Total Population                        4,498,305             5,259,387

 2020 Projected Population                    4,836,000             5,121,000

 2001 Average Life Expectancy (years)         71.9                  78.8

                                                                                                    9
These estimates are for the de facto population (e.g. including guest workers and refugees)
                         rather than de jure population (e.g. citizens and, in some Member States, permanent resi-
                         dents). As a result, these estimates may differ from official country statistics. WHO uses a
                         standard method to estimate and project life tables for all Member States (WHO, 2002).
                         This may lead to minor differences when compared to official life tables prepared by
                         Member States. A 95 % uncertainty interval is included for the average life expectancy esti-
                         mates. These intervals take into account the uncertainty in the estimates due to sampling.

                         Statistical methods

                         Age specific rates are used to display the data in the SuRF report. These were calculated
Preventive strategies,   by dividing the number of people exhibiting the risk factor of interest in each specified age
  targeting the whole    group by the corresponding survey sample in the same age group. This rate is multiplied by
                         100 to give the per-cent prevalence for particular age and sex groupings.
   population, aim to
                         The age-specific prevalence rates presented in this report also show 95 % confidence inter-
 encourage healthier     vals. Some surveys and study authors provided the InfoBase team with these values from
  behaviour and thus     their own calculations. Where this was not possible, the InfoBase team estimated the con-
                         fidence intervals, assuming a binomial distribution for the risk factor of interest in the
   reduce exposure to    specified age range. These estimations were only done for the total age range provided by
                 risk.   the study.

                         For some countries with national risk factor surveys, the age-specific prevalence rates from
                         the survey are weighted to the estimates of the national population, either from a recent
                         population census or from demographic models. If the national survey used a sampling
                         frame with no systematic biases and good population coverage, these weighted prevalence
                         values provide a reasonable estimate of national risk factor prevalence. In these cases, the
                         SuRF report provides the weighted national prevalence estimate along with the actual survey
                         sample size in the country profiles. This presentation is noted in the accompanying text.

                         Risk Factors

                         Risk factors are displayed following the order as outlined in the STEPwise approach to
                         Surveillance of NCD risk factors (STEPS; Bonita et al., 2001). STEPS is a sequential pro-
                         gram that focuses on building and strengthening country capacity for middle and low
                         income countries to collect, on a periodic basis, small amounts of high quality risk factor
                         data (Bonita et al. 2001; Figure 2). Step 1 is the collection of self-reported information
                         about health behaviours, including tobacco use, alcohol consumption (heavy drinkers and
                         abstainers), diet and physical inactivity. Step 2 focuses on objective standardized physical
                         measurements to collect data on blood pressure, height and weight. Finally, Step 3 collects
                         blood samples to measure lipids (cholesterol) and glucose status (for diabetes).

                         The SuRF report presents risk factors in accordance with the STEPwise approach to
                         Surveillance of NCD risk factors (STEPS) protocol (Bonita et al., 2001). Key health behav-
                         iours collected in Step 1 are reported first, followed by obesity/BMI and raised blood pres-
                         sure from Step 2, and finally, raised blood lipids and diabetes from Step 3. The order in
                         specific country profiles depends on data availability. Many countries have limited data
                         which may not cover all of the NCD risk factors included in this report. As a result, their
                         risk factor profiles may be incomplete. However, countries with incomplete data have the
                         opportunity to begin collecting standardized data using STEPS.

                   10
Figure 2
 The WHO STEPs approach to NCD surveillance

 The conceptual framework offers a distinction
 between different levels of risk-factor
 assessment: Information by:
 – questionnaire                                           Optional 3

 – physical measerements                                       Optional 2

 – blood samples;
                                                                   Optional 1

 and three modules offering different
 quantity of detail of each risk factor:                                Expanded

 – core
 – expanded core, and
 – optional                                                                        Core

WHO’s approach to risk

Risk of disease generally increases along a continuum of risk factor exposures, resulting in a
continuous population distribution of risk (Rose, 1992). For convenience, clinicians often focus
on interventions for those at the far end of the spectrum, i.e. those considered to be at “high
risk” of disease. This focus creates arbitrary, dichotomous categories for those considered to be
at risk, for example, systolic blood pressures greater than 140 mm Hg or greater than 160 mm
Hg. However, many people with lower risk exposures will develop disease. Furthermore, the
bulk of the disease burden occurs where the greatest proportion of the population is exposed to
risk and this may occur below a particular “high risk” threshold. As a result, preventive strate-
gies that focus on shifting the entire distribution of the risk factor will prevent more disease
than would be the case if only high risk groups were targeted. Preventive strategies, targeting
the whole population, aim to encourage healthier behaviour and thus reduce exposure to risk.

WHO uses a population-based approach to risk and prevention (WHO, 2002). For this reason,
the SuRF report includes, whenever possible, data on the mean values of risk factors that are
distributed in a continuous manner. These are systolic blood pressure, BMI, total blood cho-
lesterol and blood glucose. The addition of these factors means that the profile for a country
with good data collections can include up to 13 risk factor variables (see Figure 3 below).

Figure 3

 Health Behaviours

 – Tobacco use
                                           Physiological Factors
 – Alcohol consumption (heavy)
                                           – Obesity/overweight (& mean BMI)              Disease outcomes
 – Alcohol abstainers
                                           – Raised blood pressure (& mean systolic       – Heart disease
 – Physical inactivity                       blood pressure)
                                                                                          – Stroke
 – Fruit/vegetable intake                  – Raised lipids (& mean total cholesterol)
                                                                                          – Cancers
                                           – Diabetes (& mean blood glucose)
                                                                                          – Diabetes

The preferred definitions for these risk factors are outlined in the next section.                           11
Risk Factor methodology
                         Tobacco use

                         The dried leaf of the plant, Nicotiana tabacum, is used globally in many forms including
                         smoking, chewing or snuff. The product is cultivated in many regions and can be legally
                         purchased around the world.

                         In many countries, cigarette smoking is only a small part of actual tobacco use. In fact, in
                         some places, more people use huqqa, bedi, snuff or some form of chewing tobacco than
                         manufactured cigarettes. For these situations, the SuRF profiles also include available data
The current pattern of   on other forms of tobacco use. The current pattern of tobacco use predicts the future bur-
                         den of lung cancer and other smoking related disease. Policy makers can use this informa-
 tobacco use predicts
                         tion to implement prevention strategies to avoid this burden. From this perspective, past
    the future burden    smoking patterns are less important because they relate directly to the current burden of
                         tobacco use in a country, not the future, preventable burden. The focus is on current, daily
   of lung cancer and
                         tobacco users therefore data on occasional and former users is not reported here.
other smoking related
                         Although comparable data on tobacco use are not widely available, most countries report
             disease.    some population-level statistics on tobacco use. WHO headquarters and Regional Offices
                         produce regular country profiles for tobacco use and a wide range of other tobacco related
                         statistics. A joint venture by WHO, the Centres for Disease Control (CDC) and the American
                         Cancer Society (ACS), known as the NATIONS Tobacco database stores not only tobacco
                         prevalence data from most countries but a variety of important information about tobacco
                         control policies and legislation in these countries. In addition to published reports and on-
                         line databases, WHO has developed, in collaboration with the CDC, the Global Youth
                         Tobacco Survey (GYTS). The GYTS is now the largest global surveillance system for any
                         major public health risk. It is operational in 150 countries and has completed question-
                         naires on over one million young people between the ages of 13 and 15 years in randomly
                         selected schools. The SuRF report displays data from the published GYTS surveys.

                         The definitions for tobacco use supplied by the survey sources are used in the country pro-
                         files. No attempt has been made to standardize these definitions. The most common desig-
                         nations include:
                         – Current daily smoker (including definitions of “at least one cigarette per day”);
                         – Smoker;
                         – Regular smoker; and
                         – User of some form of tobacco (including multiple sources).

                         Most surveys specify the meaning of “smoker” and “regular smoker” but often this is not
                         recorded. Where additional information is included about a definition, it is recorded in the
                         NCD InfoBase and it is displayed in the risk factor definition section of the country profile.
                         Table 2 shows the variety of definitions used to collect tobacco use prevalence data. For
                         reasons mentioned above, the preferred definition is “current daily smoker”.

                    12
Table 2 Selected examples of definitions used and age groups included in surveys to collect prevalence
        of tobacco use.

 Definition                                          Age groups (years)        Country of origin of the Source

 Current daily smoker                                various combinations      various

 Regular smoker                                      various combinations      various

 smoker                                              various combinations      various

 Smoker; cigarettes                                  13-15                     GYTS for various countries

 Uses some form of tobacco (includes                 18+                       Afghanistan
 multiple sources)

 Current daily smoker:                               20-89                     Venezuela
 > 10 cigarettes per day

 Chew paan masala or tobacco                         15+                       India

 Smoker (includes daily smoker) once a week          25-69                     Bangladesh
 at least and less than once a week

 Regular current smoking                             12-45                     Paraguay

 Smoker; 1 to more than 15 cigarettes per day or     18+                       Haiti
 1 to more than 2 pipe fulls of tobacco per day

 Smoking or chewing tobacco leaf with betel quid     18-75                     Bangladesh

Alcohol Consumption

Alcohol consumption has many health and social consequences resulting from intoxication
and dependence. Direct health consequences range from automobile accidents and domes-
tic violence to chronic health and social problems (WHO, 1999). However, there are also
reported beneficial relationships between low to moderate drinking in a non-binge pattern
and coronary heart disease, stroke and diabetes mellitus (Rehm et al., 2001).

The definitions used for population-based data on alcohol consumption vary widely from
country to country. Many countries do not collect this information at all because alcohol
consumption is not permitted in their societies for religious reasons. Other countries collect
and report the information without a standard definition for heavy consumption. The coun-
try profiles display the definitions used by the survey source with the aim of providing the
most specific definition possible for high alcohol consumers. Table 3 provides examples of
the variety of definitions for high alcohol consumption that are routinely reported. The
WHO STEPS survey instrument uses 7 day recall of number of standard drinks to quantify
proportion of adults engaged in “at risk levels” of drinking.

Similarly, definitions for alcohol abstainers differ from country to country. Many studies
consider only those who report ‘never drink alcohol’, while others simply report ‘abstainers’.
Often, there is no way to differentiate between those who have tried alcohol but choose not
to drink and those who have never had a drink. However, this distinction is unlikely to
affect the overall risk profile at the population level.
                                                                                                                 13
Table 3 Selected examples of definitions and age groups included in surveys to collect prevalence of high alcohol
                                  consumption.

                           Definition                                           Age groups                Country of origin of the source

                           reported alcohol dependency                          various combinations      Various

                           drink alcohol                                        15 +                      Cameroon and various

                           daily drinkers                                       various combinations      Various

                           the ingestion of 100 cc of absolute alcohol          12-45                     Paraguay
  There is no interna-     at one time (opportunity)

tionally agreed defini-    alcohol consumption at least one time per year       12-49                     Mexico

    tion or measure of     20+ g of alcohol daily intake                        20-49                     Czech Republic

     physical activity.    0ver 0.2 L of alcohol per day                        26-62                     Bosnia and Herzegovina

                           heavy alcohol consumption in the past year;          20+                       USA
                           more than 14 drinks per week for men and more
                           than 7 drinks per week for women

                          Physical inactivity

                          Regular physical activity has health benefits including regulation of body weight and
                          strengthening of the cardiovascular system (CDC, 1996). Measuring the levels of activity or
                          inactivity in a population has proved difficult. There is no internationally agreed definition
                          or measure of physical activity. To add to the problem, physical activity exists in multiple
                          domains of a person’s life, from main occupation (especially if the job involves physical
                          labour), to means of transport, domestic duties and leisure time.

                          The SuRF report focuses on lack of activity as a risk factor for poor health outcomes, includ-
                          ing overweight/obesity and cardiovascular disease. Again, definitions of physical inactivity
                          vary in different country settings. Often high and middle income countries report activity or
                          inactivity in “leisure” time, a concept that may not exist in low income situations. Most
                          available data are for leisure-time activity while little data are available for activity relating to
                          work, transport or domestic tasks.

                          The country profiles display the definition provided by the survey source. Sometimes, surveys
                          choose to provide information related to specific activity levels as well as inactivity. Preference
                          was given to including data in the country profiles that relate to physical inactivity rather
                          than physical activity. The most frequently used definitions for physical inactivity are
                          “sedentary” or “no exercise” categories.

                          The WHO STEPS survey instrument measures physical activity/inactivity across three domains
                          of life: work, leisure time and transport. It uses an activity score based on intensity of activity
                          and time spent in activity to calculate the proportion of inactive adults.

                          Fruit and Vegetable intake

                          Fruits and vegetables are important components of a healthy diet designed to regulate
                          weight and provide appropriate nutrients for growth and development. Low fruit and veg-
                          etable intake is causally linked to incidence of cancer and heart disease (Ness and Powles,
                    14    1997; World Cancer Research Fund and American Institute for Cancer Research, 1997).
Health promotion programmes emphasize the importance of eating five or more servings of
fruit and vegetables combined a day. Some developed countries collect this information in
their national health surveys. Other surveys collect information on presumed average fruit
and vegetable intake per capita. Still others find it easier to report ‘never eats fruit’ or
‘never eats vegetable’ as categories. The country profiles in the SuRF report display the
definitions given by the survey source.

Definitions that designate the part of the population that is not eating enough fruit and
vegetable are preferred because they relate directly to the risk category of low fruit and
vegetable intake. Such definitions include “less than or equal to five fruit and vegetable
servings per day”, “never eats vegetables”, and “never eats fruit”.                                                 Health promotion
The WHO STEPs survey instrument collects information on how many servings of fruit and                              programmes empha-
vegetable are eaten on a typical day and uses this information to calculate the proportion
of adults who are not eating 5 or more combined servings of fruit and vegetable.                                    size the importance

Obesity and overweight                                                                                              of eating five or more

The prevalence of obesity and overweight is commonly assessed using body mass index                                 servings of fruit
(BMI, kg/m2). This formula has a strong correlation to body fat content. The WHO criteria                           and vegetables
define overweight as BMI greater than or equal to 25 kg/m2 and obesity as BMI greater
than or equal to 30 kg/m2 (WHO, 2000). These criteria provide a benchmark for measuring                             combined a day.
overweight and obesity but the risks of disease in a population increase progressively from
BMI levels of 20 to 22 kg/m2.

BMI generally increases with age, peaking in the middle-aged and elderly, who are at great-
est risk of health complications. The increase corresponds to higher levels of free sugars
and saturated fats in the diet combined with reduced physical activity.

Many surveys report prevalence of obesity and overweight using the WHO criteria for meas-
ured height and weight and this is the preferred definition. However, a variety of other defi-
nitions are also displayed in the country profiles, reflecting what is being collected at the
country-level. Table 4 displays examples of the variety of obesity definitions currently in use.

Often the BMI categories reflect self-reported height and weight and this is indicated in
the country profile definitions. Measured data is preferred because self-reported height and
weight may differ significantly from measured height and weight and the deviations will
result in biased BMI estimates (Waters, 1993). Mean values for BMI in specific age group-
ings are preferred in line with WHO’s population-based approach to distribution of risk
exposures (WHO, 2002).

Table 4 Selected examples of definitions used and age groups included in surveys to report prevalence of obesity.

 Definition                                          Age groups                 Country of origin of the source

 BMI>=25 (stated to define obese)                    various combinations       various

 BMI>=30                                             various combinations       various

 BMI greater than or equal to 27.8 for males         20-70                      Argentina
 and 27. 3 for females

 BMI greater than 27 for males and greater           20+                        Cook Islands; Kiribati
 than 25 for females
                                                                                                                    15
Raised blood pressure

                          Blood pressure is a measure of the force that the circulating blood exerts on the walls of the
                          main arteries. The highest (systolic) pressure is created by the heart contracting and the low-
                          est (diastolic) pressure is measured as the heart fills. Raised blood pressure is almost always
                          without symptoms but the result is structural damage to the arteries that supply blood to
                          the major organs of the body. This damage eventually results in stroke, ischaemic heart dis-
                          ease, renal failure and other diseases. It is becoming increasingly clear that the risk of these
                          conditions is not limited to those with particularly high levels of blood pressure, but also for
                          those with average or even below average levels of blood pressure (Law and Wald, 2002;
 Studies that measure     Eastern Stroke and Coronary Heart Disease Collaborative Group, 1998).

    blood pressure are    Studies that measure blood pressure are preferred to those that collect self-reported raised
                          blood pressure status. Still, many national health surveys lack the capacity to collect the
preferred to those that   measured data for their large survey samples. In the SuRF report, country profile defini-
  collect self-reported   tions include the status of the data as measured or self-reported. The most common desig-
                          nation for the prevalence of raised blood pressure is ‘systolic blood pressure greater than or
 raised blood pressure    equal to 140 mm Hg and/or diastolic blood pressure greater than or equal to 90 mm Hg’.
               status.    Often those on anti-hypertension medication are also included in the definition (Table 5).
                          Some surveys prefer to use a higher definition for raised blood pressure and include only
                          those with ‘systolic blood pressure greater than or equal to 160 mm Hg and/or diastolic
                          blood pressure greater than or equal to 95 mm Hg. This definition may or may not include
                          those on anti-hypertension medication. It is clear that such a definition is inadequate for
                          surveillance purposes, especially for a population-based approach to preventing cardiovas-
                          cular disease.

                          Recognizing the limitations of the above definitions, many surveys are also starting to report
                          measured mean systolic blood pressure as a preferred indicator of risk exposure. The country
                          profiles display age-specific mean systolic blood pressure data as well as prevalence of hyper-
                          tension where they exist for a country. This is in line with WHO’s preference for a population-
                          based approach to risk factor exposure, moving away from a focus on “high risk” categories
                          of exposure (WHO, 2002).

                          Raised blood lipids

                          The blood lipid reported in most surveys is raised total blood cholesterol. Cholesterol is a
                          fat-like substance found in the blood stream, nerve fibres and major body organs. High lev-
                          els of cholesterol are associated with heredity, diabetes mellitus and a diet high in saturat-
                          ed fats. Raised cholesterol is an important cause of artherosclerosis, the accumulation of
                          fatty deposits on the walls of the arteries. The result is an increased risk of stroke,
                          ischaemic heart disease and other vascular diseases. As with raised blood pressure, the
                          risks of cholesterol are continuous and extend across almost all levels seen in different
                          populations (Prospective Studies Collaboration, 1995). Ideally, for surveillance purposes,
                          mean levels of total cholesterol in specified age and sex groups are recommended.

                          From the SuRF report, it can be seen that surveys describe the prevalence of raised lipids
                          (cholesterol) using a variety of different definitions. The most common are total cholesterol:
                          – greater than or equal to 6.5 mmol/l;
                          – greater than or equal to 5.5 mmol/l; and
                          – greater than or equal to 5.2 mmol/l.

                          Often cholesterol levels are reported in units of mg/dl. In these cases, 240mg/dl corre-
                          sponds to 6.5 mmol/l.
                    16
Table 5 Selected examples of definitions used and age groups included in surveys to report prevalence of raised
        blood pressure.

 Definition

 Self-report                           ever diagnosed

                                       ever diagnosed by a medical practitioner

                                       recent diagnosis of hypertension

                                       on medication for hypertension
                                                                                                                   For surveillance
 Measured blood pressure (mmHg)        systolic blood pressure > 140                                              purposes, mean levels
                                       systolic blood pressure >= 140 and diastolic blood pressure >=90           of systolic blood
                                       systolic blood pressure >= 140 and/or diastolic blood pressure >=90        pressure in specified
                                       systolic blood pressure >= 140 or diastolic blood pressure >=90            age and sex groups are
                                       systolic blood pressure >= 140 and/or diastolic blood pressure >=90        recommended.
                                       or being treated with anti-hypertension medication

                                       systolic blood pressure > 160

                                       systolic blood pressure >= 160 and diastolic blood pressure >=95

                                       systolic blood pressure >= 160 and/or diastolic blood pressure >=95

                                       systolic blood pressure >= 160 or diastolic blood pressure >=95

                                       systolic blood pressure >= 160 and/or diastolic blood pressure >=95
                                       or being treated with anti-hypertension medication

                                       systolic blood pressure >=160 and/or diastolic blood pressure >=100

As for the other risk factors, the SuRF report country profiles display the definitions, as
available, from the survey source. Mean total blood cholesterol by age group and sex is
sometimes reported by surveys. This is included in the country profiles, where available,
in accordance with WHO’s population-based approach to risk exposure and recognized in
the WHO STEPwise approach to Surveillance of NCD risk factors (WHO, 2002).

Diabetes

Diabetes is a group of disorders resulting from insulin deficiency, impaired effectiveness of
insulin action or both (IDF, 2000). Insulin impairment leads to high levels of glucose in
the blood as the body cannot break down this basic sugar. Diabetes mellitus is a serious
condition in itself, but is also a risk factor for other conditions including blindness, renal
failure, macro-vascular diseases, such as stroke, and ischaemic heart disease. There are
four different types of diabetes based on aetiology and clinical presentation. These are type
1 diabetes, type 2 diabetes, gestational diabetes and other specific types of diabetes. Data
on diabetes prevalence for the SuRF report focuses on type 2 diabetes, which is character-
ized by insulin resistance and relative insulin deficiency (IDF, 2000). The onset of this
form of diabetes usually occurs after the age of 40 and is often associated with obesity.

                                                                                                                  17
The SuRF report includes data on the prevalence of diabetes which is presented with well-
     defined detection methods and diagnostic criteria. Detection methods of choice are a fast-
     ing blood glucose measure and/or an oral glucose tolerance test (using a 75 gram glucose
     load). The preferred diagnostic criteria are those of WHO from one of the following three
     time periods, 1980, 1985 and 1999 (Table 6). Most good quality studies use the WHO cri-
     teria that correspond to the period in which the survey was performed.

     The cut-off point for fasting blood glucose concentration has been lowered, meaning that
     the number of people considered to be diabetic now is different than in the past, based on
     this screening test. For the oral glucose tolerance test (OGTT), the diagnostic blood glucose
     concentration has remained the same. The OGTT is the preferred measure of diabetes in
     the population because it also detects impaired glucose tolerance and it provides a consis-
     tent measure of the prevalence of diabetes in populations over time. However, the OGTT
     requires a level of resources which is beyond the capacity of most countries for
     Surveillance purposes and is not recommended in the WHO STEPwise approach to
     Surveillance of NCD risk factors.

     Exact definitions, as reported by survey sources, have been provided in the country profile
     definitions. Where WHO criteria are used as definitions, this is recorded with the designa-
     tion “WHO, year”. Many national health surveys collect self-reported information on dia-
     betes status by using a questionnaire that asks whether or not the participants have been
     diagnosed with diabetes by a medical professional. While measured, population-level data
     are more accurate, self-reported information does provide base line data where none would
     otherwise be collected.

     Table 6 Diagnostic values for the oral glucose tolerance test for diabetes mellitus: WHO definitions for 1980,
             1985 and 1999 compared.
      Diagnostic criteria          Glucose concentration mmol/litre (mg/dl)
      for diabetes mellitus
      compared

                                   W H O L E           B L O O D              P L A S M A

                                   venous                capillary            venous                capillary

      Fasting value

      1980                         >=7.0                 >=7.0                >=8.0                 –

      1985                         >= 6.7 (>=120)        >= 6.7 (>=120)       >=7.8 (>=140)         >=7.8 (>=140)

      1999                         >=6.1 (>=110)         >=6.1 (>=110)        >=7.0 (>=126)         >=7.0 (>=126)

      OGTT: 2 hours post
      glucose load of 75 grams

      1980                         >=10.0                >=11.0               >=11.0                –

      1985                         >=10.0 (>=180)        >=11.1 (>=200)       >=11.1 (>=200)        >=12.2 (>=200)

      1999                         >=10.0 (>=180)        >=11.1 (>=200)       >=11.1 (>=200)        >=12.2 (>=200)

18
Data sources
Considerable time and effort has gone into deciding the type of information most useful for
surveillance of NCD risk factors. The collection is limited to data that is strictly relevant to
NCD outcomes; i.e. mortality and morbidity from NCDs. As previously mentioned, the risk
factors chosen are those that:
– make the greatest contribution to mortality and morbidity from chronic disease;
– can be changed through primary intervention; and
– can be measured easily in populations.

The NCD InfoBase includes all NCD risk factor data, regardless of sampling frame and rep-          Reporting data without
resentativeness, but allows users to select the survey and data that suit their purposes. The
SuRF report focuses on most recent, most representative surveys for WHO Member States.             any information on

Reporting data without any information on source and survey methods limits its usefulness          source and survey
for policy decisions or further research. Information about measurement methods, defini-           methods limits its
tions, and age groups is needed to determine if data are comparable to that of other sur-
veys (both within and between countries) or representative of their respective populations.        usefulness...
For these reasons, this report strives to present the data collection for each Member State
with:
– source population information;
– risk factor definitions;
– age group(s);
– sex; and
– some measure of the uncertainty of the estimate (i.e. confidence interval,
   standard deviation).

Often this information is missing when data is presented in journal articles. In these cases,
additional steps were taken to complete the information by following up with study authors
or those responsible for the study. These collaborators are acknowledged in the CD-ROM
attachment of this report and on the country profiles displaying the data that they provided.

Country-level sources
The availability of risk factor data varies from country to country. For the NCD InfoBase,
data have been obtained primarily from published sources. For some countries, available
data are restricted to small, ad hoc surveys published in academic journals. WHO Regions
that contain many developed countries have a wider variety of survey instruments available
to them. Examples of data sources for WHO regions are illustrated below.

European Region

Countries in the WHO European Region (EURO) have access to a number of health surveys
and data collection resources. In 1997, the European Commission established a Health
Monitoring Programme (HMP) which has now been superseded by a New Public Health
Programme sponsored by the European Parliament and Council. This programme will start
in January 2003 and run until 2006. The European Health Monitoring Project and the
European Health Interview Surveys are two current projects of the HMP. There are also a
variety of other instruments available that capture some NCD risk factor information includ-
ing the Eurobarometer and the European Community household panel.

                                                                                                   19
The Countrywide Integrated Noncommunicable Diseases Intervention Programme (CINDI)
     also collects risk factor information related to evaluation of country programmes. The
     CINDI surveys have been implemented in 27 European countries. In addition, many EUR
     countries have national health surveys run by their own Ministries of Health. To date, EUR
     risk factor data have not been harmonized for use in country comparisons.

     Region of the Americas

     The WHO Region for the Americas (AMR), in contrast to EUR, has many national health
     survey instruments but no co-operating programmes to try to harmonize data collections.
     However, the Conjuntos de Accionnes para la Reduccion Multifactorial de Enfermadades
     No transmisibles (CARMEN) network seeks to adopt standard data collection for non-com-
     municable disease risk factors.

     Several long-term national efforts exist including the national health surveys from the
     Instituto Nacional De Salud Publica of Mexico, National Health and Nutrition Examination
     Surveys run by the Centers for Disease Control in the USA and the Canadian National
     Population Health Survey from Statistics Canada. Other countries rely on academic
     research studies to provide base-line data on NCD risk factors.

     South-East Asia Region and Western Pacific Region

     The South-East Asian Region (SEAR) and the Western Pacific Region (WPR) both contain
     some countries that routinely collect NCD risk factor data with national survey instruments.
     Other countries in these regions rely on research studies done by cardiovascular research
     institutes/ foundations or universities. Both Regional Offices have set up networks to sup-
     port surveillance and interventions to prevent NCDs and their risk factors. For the WPR,
     the network is known as Mobilization of Allies in Noncommunicable Disease Action
     (MOANA). For SEAR, the network name is still under consideration.

     Eastern Mediterranean Region

     The countries in the Eastern Mediterranean Region (EMR) have some NCD risk factor infor-
     mation collected by Ministries of Health. Other studies are specific to institutes and aca-
     demic departments that focus on cardiovascular diseases (i.e. Tehran Lipid and Glucose
     Study from Tehran, Iran and the Dar Al Fatwa Community Household Survey of Beirut,
     Lebanon). The Eastern Mediterranean Approach to Non-Communicable Diseases network
     (EMAN) is working towards standard collection of NCD risk factor data.

     African Region

     The African Region (AFR) has the least number of national health surveys that report NCD
     risk factors with only a few examples of national collection efforts (South Africa, Tanzania,
     Nigeria). Others have national-level surveys done by researchers from outside of the country
     (Mauritius). Several national statistical agencies collect health-related information, mainly
     on number of providers, maternal and child health status and reportable communicable
     diseases. Preferential collection of such indicators reflect the health priorities of these
     countries. However, as the World Health Report 2002 warns, rising levels of NCD morbidity
     and mortality will occur in the near future in these countries, due to increasing levels of
     tobacco use, raised blood pressure and raised cholesterol levels (WHO, 2002). The Africa
     Noncommunicable Diseases Intervention network (NANDI) is working to spread the message
     that NCD risk factors are a rising problem in the region.

20
Where countries have large, nationally representative surveys, the SuRF country profiles
display their weighted prevalence estimates along with the unweighted sample sizes used
in the survey. This display provides the level of information needed by policy makers to use
the data effectively. If the sampling frame is representative of the national population and
is without systematic bias, the weighted estimates are considered to be the best risk factor
prevalence estimates for that country.

Additional survey instruments

Data for a range of countries are provided by established networks, institutions or commer-
cial companies that focus on collecting health information. One such data source is the
published collections of the WHO Multinational Monitoring of Trends and Determinants            Many of the problems
in Cardiovascular Disease, otherwise known as the WHO MONICA project. The MONICA                related to validity
Project’s objective was to measure the trends and determinants in cardiovascular disease
mortality and morbidity in selected, well-defined populations and to relate these trends to     of data can be solved
changes in known risk factors, daily living habits, health care, or major socio-economic fea-   by agreeing to
tures measured at the same time in different countries (Tolonen et al., 2002). Standard
methods for collecting risk factor data were developed and used by the 32 individual col-       standardized survey
laborating centres that participated in the project (Tunstall-Pedoe, 1988). An emphasis         instruments
was placed on training interviewers to use the standard methodology (Tolonen et al.,
2002). Published data are available, mainly for developed countries, by 10 year age and
sex groups starting at age 25 and ending at age 64. The risk factors measured were tobac-
co use (smoking), (measured) blood pressure, (measured) blood cholesterol, and obesity
(measured height and weight).

Macro International Inc. provides survey and market research information to clients in busi-
ness and government. They run demographic and health surveys for Ministries of Health in
many low and middle income countries. The surveys generally focus on the health of women
of child bearing age and children only and so have been of limited use for this report. Some
surveys collect data on tobacco use prevalence as well as measured height and weight (in
women of reproductive age). Where relevant, this data is included in the NCD InfoBase.

Gaps and deficiencies in data

Valid, reliable and comparable data are all needed for research and health monitoring. At the
population-level, there is more concern with measurement accuracy (validity) rather than
reliability (i.e. how good the measure is in relation to the “true” population measure). If
the measurement and sampling is without systematic bias and is of adequate size, there
should be an average estimate that approximates the true population estimate with a known
level of confidence. Appropriate health policy decisions can be made on the basis of this
known level of confidence for a prevalence estimate.

Many of the problems related to validity of data can be solved by agreeing to standardized
survey instruments, including standard age categories. Many European countries are now
moving towards a standard data collection format with the European Health Interview
Survey (EUROHIS; Vermeire et al., 2001).

However, valid data need not be comparable data. The major limitation of the data present-
ed in SuRF Report 1 is that it is not comparable between surveys. This is unquestionably
true of survey data from different countries. Even within a country, when trend data are
available, the data may not be comparable. Part of the problem is the use of different sur-
vey instruments, different measurement methods and different criteria for a clinical out-
come (i.e. diabetic or hypertensive). An additional problem occurs with risk factor variables
                                                                                                21
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