Study constraints in African and other epidemiological surveys.

Studies on rheumatoid arthritis (RA) in developing countries have suffered from numerous constraints in the application of historical, clinical, radiological, and serological criteria for disease. The Manchester grading for clinical RA turned out to be the best set of criteria in Africa. Erosions on radiographs and a positive rheumatoid factor are of little help as the prevalence of both is high in most African populations. Living at high altitude and hence being void of most tropical parasitic infections apparently increases prevalence figures for RA. More studies are needed from developing countries to determine the magnitude and the determinants of disabling rheumatic conditions.