Rheumatoid arthritis in a tribal Xhosa population in the Transkei, Southern Africa
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Annals of the Rheumatic Diseases, 1977, 36, 62-65
Rheumatoid arthritis in a tribal Xhosa population in
the Transkei, Southern Africa
0. L. MEYERS,* G. DAYNES, AND P. BEIGHTON.
From Groote Schuur Hospital and Department of Medicine, University of Cape Town Medical School;*
St. Lucy's Hospital, Tsolo, Transkei:t and Department of Human Genetics, University of Cape Town Medical
School,+ South Africa
SUMMARY An epidemiological survey of rheumatoid arthritis (RA) was undertaken in a tribal
Xhosa community in the Transkei of Southern Africa. 577 respondents aged 18 and over were
examined clinically and of these, 549 were investigated radiologically and 482 serologically. The
presence of RA was then assessed by means of a modification of the Rome criteria, as used in previous
comparable surveys.
The prevalence of 'definite' RA in the adults aged 18 and over in this population was 068 %° and
of 'probable' RA, 1 6 %. The combined 'definite' and 'probable' prevalence was 2-2 %. The relatively
low prevalence of RA in this population is consistent with the results of other surveys in unsophisti-
cated African Negro populations in West Africa and South Africa, and contrasts with the higher
prevalence encountered in an urbanized South African Negro community and in populations in
Europe and the USA.
It is well established that there are considerable population is descended from the Negroes of
geographical variations in the prevalence of rheuma- Central Africa and is closely related to other Bantu-
toid arthritis (RA) (Lawrence et al., 1966). Uncer- speaking groups such as the Zulu and the Tswana.
tainty remains as to whether these discrepancies are The community lived in tribal circumstances
the result of ethnic or environmental factors. with an unsophisticated life-style, the cultivation of
However, recent epidemiological studies in South maize and cattle husbandry being the main occupa-
Africa have indicated that although RA is very tions. As a large proportion of the males had
uncommon in African Negroes living in a rural migrated to the cities to find employment, there was
environment, the prevalence in urbanized Africans a preponderance of females in the population.
approaches that normally encountered in Western The villages have been served by St. Cuthbert's
Europe (Beighton etal., 1975; Solomon et al., 1975a). mission and St. Lucy's Hospital since the last cen-
If RA is indeed rare in the rural Negro population tury, and the unstinted collaboration of the respon-
of this country, it is reasonable to suppose that the dents in the survey was the result of this long-stand-
condition would be equally uncommon in less ing relationship. Demographic details have been
sophisticated tribal circumstances. In order to fur- given in a companion paper concernig serum
ther elucidate this situation and to confirm the uric acid concentrations in this tribal Xhosa popula-
previous findings, an epidemiological investigation of tion (Beighton et al., 1976).
RA was undertaken in a Xhosa community, living
in a tribal environment in the Transkei. Methods
Population The investigation techniques were similar to those
used in previous surveys in the South African series
The survey concerned the inhabitants of 2 adjacent (Solomon et al., 1975 a, b) and the description of the
villages, Zinchuka and Esingeni, in the Tsolo dis- methodology of the present survey is therefore con-
trict of the Transkei, South Africa. This Xhosa fined to a brief outline.
Accepted for publication May 17, 1976
Correspondence to Prof. P. Beighton, Department of Human SURVEY METHODS
Genetics, Medical School, Observatory 7900, South Africa A preliminary census was carried out in randomly
62Downloaded from http://ard.bmj.com/ on May 8, 2015 - Published by group.bmj.com
Rheumatoid arthritis in a tribal Xhosa population 63
selected areas in the two villages to give information Results
on the basic structure of the population and to pro-
vide a pool of potential respondents. During June CLINICAL ASSESSMENT
and July 1973, using the facilities of St. Lucy's 577 respondents aged 18 years and over were exam-
Hospital, the respondents were examined clinically, ined for objective evidence of inflammatory arthritis.
radiographs were obtained of their hands, and This was considered to be present in 10 of them. 3
venepuncture was undertaken in all individuals aged females, aged 50, 76, and 78 years, fulfilled the
18 and over. Anteroposterior radiographs of the criteria for definite RA. Of these, one had severe
pelvis and hip joints, and lateral views of the crippling arthritis, advanced grade 4 erosive arthritis,
lumbar spine were also obtained in a proportion of and positive tests for RF. The other 2 women had a
adults, aged 45 and over, for studies of other mild polyarthritis, grade 2 erosive arthritis, and
skeletal conditions. positive tests for RF. The remaining 7 respondents
In the concluding phase of the survey the patients who were considered to have an inflammatory
were visited in their homes to ensure adequate arthritis all had very mild disease. None of these
completion rates. Completion rates were 96 % for respondents showed any radiological evidence of RA
the clinical aspects, 91 % for the radiographic but 2 had positive tests for RF (one had positive
studies, and 80 % for the serological investigations. LFT and HEAT).
None of the 400 respondents aged 17 or under had
LABORATORY METHODS any clinical evidence of polyarthritis. However, as
Sera were separated within 4 hours of collection, their serological and radiographical status was not
stored at 20°C, and transported by air in insulated
- investigated, this group have been deliberately
containers to the Medical School, University of Cape excluded from the polyarthritis aspect of the survey.
Town. Rheumatoid factor (RF) in the serum was No respondent had any clinical or radiographic
measured by two methods: the human latex fixation evidence of ankylosing spondylitis.
test (LFT) and the human erythrocyte agglutination
test (HEAT). For the sake of conformity with RADIOLOGICAL ASSESSMENT
previous investigations the LFT was carried out The radiographs of 549 respondents aged 18 or
after prior heating of the serum to 56°C (LFT56), over were examined for evidence of erosive arthritis
according to the modification introduced by by one investigator (O.L.M.). There were 18 exam-
Valkenburg (1963). An LFT56 titre of in 640 or over ples of grade 2 changes (14 females, 4 males) and
and an HEAT titre of 1 in 32 or over was considered one subject with advanced RA. In addition, a single
to be positive. All sera were also tested for RF pocketed lesion was present in 8 instances. These
by the standard Singer and Plotz method (Singer minor abnormalities were not accepted as evidence
etaL., 1962.) of erosive arthritis because of their consistent
location on the medial side of the base of the third
EVALUATION OF RA BY COMBINED CRITERIA or fourth proximal phalanges. This uniformity of
In the previous surveys in South Africa it became appearance and distribution suggested that some
apparent that a clinical history was unreliable, mechanism other than RA was operative.
owing to language barriers and to differing cultural Apart from the 3 subjects who were considered
concepts of disease processes. For this reason a to have definite RA, none of the respondents with
modification of the 'Rome criteria' (Kellgren et al., erosive changes had any clinical evidence of inflam-
1963a, b) was used to assess the presence of RA. The matory arthritis. 9 of the respondents with grade 2
following objective criteria were used. radiological changes also had positive tests for
(i) Clinically apparent symmetrical deformity of RF (LFT 9, HEAT 2).
peripheral joints, especially of the metacarpo-
phalangeal or metatarsophalangeal joints, with S ROLOGICAL ASSESSMENT
involvement of at least one hand or foot. The LFT56 studies were performed on the sera of
(ii) Radiographic changes of RA of grade 2 or 482 respondents (77 males, 405 females), of whom
more (de Graaf et al., 1963; Kellgren et al., 1963b). 83 were found to have positive titres. This group
(iii) Positive serological tests for RF. contained 3 subjects with 'definite' RA, 2 with a
Individuals fulfilling all 3 criteria were designated mild clinical polyarthritis, and 9 with erosive arthri-
'definite' RA, while those fulfilling 2 of the criteria tis. The remaining 71 respondents showed neither
were considered to have 'probable' RA. Diagnosis clinical nor radiological evidence of RA. The overall
was negated by any of the exclusions listed in the prevalence of positive LFTs in the survey population
American Rheumatism Association's criteria of was 17%, increasing with age from 7-2 % in the
1958 (Ropes et al., 1959). 18-24 age cohort to 19-7 % in the 65-74 age cohort.Downloaded from http://ard.bmj.com/ on May 8, 2015 - Published by group.bmj.com
64 Meyers, Daynes, Beighton
The HEAT test was performed on the sera of hand radiographs. This prevalence is a little higher
476 respondents (76 males, 400 females), of whom 10 than figures generally quoted from other parts of the
had positive titres. These HEAT-positive respon- world. However, the changes were generally of
dents comprised 2 subjects with definite RA and 8 minor degree and with one exception were grade 2
with neither clinical nor radiological evidence of or less. In 3 subjects the radiological features corre-
RA. The overall prevalence of HEAT-positive lated with clinical and serological evidence for RA,
reactions was 2-1 % and, as with the LFT, there was while in 7 subjects the radiological signs correlated
an increase in positive tests with age, ranging from with a positive RF test.
0 % in the 18-24 age cohort to 3 2 % in the 64-75 age The LFT56 was positive in 17 % of the population,
cohort. while the HEAT was positive in 2-1 %. Using the
All the sera were tested by the standard latex conventional Singer and Plotz method, the sera from
agglutination test of Singer and Plotz. 40 sera were the Xhosa population gave a positive rate of 8 6%.
proved positive by this method, and in 7 this tech- These high figures for LFT56 are similar to those
nique gave positive results when all other tests were previously reported from Nigeria and South
negative. This compares with 50 by the LFT56 Africa (Muller, 1970; Solomon et al., 1975b). As in
method. In 33 sera the 2 tests were concordant. All other populations the prevalence of positive RF
the sera of the 'definite' RA group were positive by tests increased with aging.
the Singer and Plotz method. The high prevalence of positive latex titres in the
Xhosa population could result from infection with
EVALUATION BY THE COMBINED CRITERIA tuberculosis or syphilis, both of which produce
As clinical histories were considered to be unreliable, positive latex titres, and which are common in the
these were omitted from the overall assessment. A Transkei. It is noteworthy that malaria, which has
diagnosis of 'definite' RA was accepted if the been implicated as a causative factor in LFT posi-
remaining three Rome criteria were fulfilled, and tivity in other African Negro peoples (Greenwood,
'probable' RA when two of the three criteria were 1968), is not endemic in the Transkei.
met. The low prevalence of RA in the Xhosa, assessed
577 respondents over the age of 18 years were on a basis of the modified combined criteria, is
examined clinically, and of these, 549 were investi- similar to that in the rural Tswana, and is in keeping
gated radiologically and in 482 serological studies with the data concerning tribal peoples in Nigeria
were undertaken. Adequate clinical, radiological, and (Greenwood, 1969; Muller, 1970). The reason for the
serological data were finally available in 433 respon- discrepancy in prevalence of RA in the urban and
dents and these were then analysed by the combined nonurban South African Negro groups is unknown.
criteria. However, in view of the ethnic similarity of the two
Three respondents were considered to have groups previously studied, genetic factors do not
'definite' RA, representing a prevalence of 0-68 % seem to play a major role. It may be relevant that RA
for individuals aged 18 and over. 7 respondents met appears to be a relatively recent disease in Western
two of the criteria for 'probable' RA, giving a Europe, and it could be postulated that unknown
prevalence of 1 6 %. The combined 'definite' and environmental factors are responsible for the
'probable' RA prevalence was 22 %. variations in distribution of RA in Southern
Africa.
Discussion Lifestyles are changing in this country. It is
important that the problem of distribution of RA
Clinically apparent inflammatory polyarthritis was is elucidated while tribal and rural cultural groups
present in 1-7% of 577 respondents aged 18 years still live alongside urbanized peoples of similar
and over. The stigmata of the disease were mild ethnic stock.
and with one exception none of the characteristic
deformities of RA was encountered. This individual We are grateful to the Xhosa community for their
had the classical changes of RA, and was bedridden. willing participation, and to the Department of
These findings are in accordance with those of the Bantu Administration for their permission for the
previously mentioned study in the rural Tswana survey to be carried out. We are indebted to Mrs
people of South Africa and with the reports concern- Greta Beighton for typing the manuscript.
ing the mild clinical manifestations of RA in Negro The investigation was supported by grants from
populations in other regions of Africa (Hall, the South African Medical Research Council, the
1966; Greenwood, 1969; Gelfand, 1969; Anderson, University of Cape Town Staff Research Fund, and
1971). the Arthritis Foundation of South Africa (Cape
Erosive arthritis was observed in 34% of 549 Western Branch).Downloaded from http://ard.bmj.com/ on May 8, 2015 - Published by group.bmj.com
Rheumatoid arthritis in a tribal Xhosa population 65
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Rheumatoid arthritis in a tribal
Xhosa population in the
Transkei, Southern Africa.
O L Meyers, G Daynes and P Beighton
Ann Rheum Dis 1977 36: 62-65
doi: 10.1136/ard.36.1.62
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