The prevalence of rheumatoid arthritis in affluent and poor urban communities of Pakistan.

Using previously applied methods a survey of joint symptoms was undertaken among 4232 adults, evenly distributed between affluent and poor areas of Karachi, Pakistan. Only six cases of definite rheumatoid arthritis (RA) (1958 ARA criteria) were identified in the 245 persons who complained of joint problems of at least 4 weeks duration. The prevalence was 0.9 [confidence interval (CI) 0.21-3.61] and 1.98 (CI 0.55-5.1) per thousand in the poor and affluent districts, respectively. These were substantially less than prevalence rates reported in the West but were similar to figures derived from other developing countries. There was no obvious impact of current living standards on the findings. The relative paucity of older female subjects in both the affluent and poor communities may account at least in part for the low rates observed. The infrequency of rheumatoid nodules in Southern Asians with RA illustrates the difficulty of applying existing diagnostic criteria to this community.