Knee pain amongst the poor and affluent in Pakistan.

The frequency of joint symptoms was determined amongst 2022 affluent and 2210 poor adults in Karachi, Pakistan. Joint pain was significantly (P = 0.025) more common amongst the affluent (6.6%) compared with the poor (5%) and this was due to a significantly greater frequency of knee pain in the richer community (3% vs 1.8%; P = 0.008). The prevalence increased with age and was more common in females. Almost half were associated with varus deformity, suggesting the presence of associated OA in a high proportion. The overall frequency of knee pain seemed no greater than in series reported from the West. Compared with age- and sex-matched controls, body weight was significantly greater amongst those with knee pain, both amongst the affluent (P = 0.005) and the poor (P = 0.02). Control subjects were heavier in the affluent population, suggesting that the greater frequency of knee symptoms in this community was due to their relative obesity. Knee bending at prayer was most common amongst the affluent controls and may indicate that religious observance also contributed to the problem in the richer population. Squatting was a characteristic of the poor who had less knee pain than the affluent. Knee flexing could not therefore be confidently implicated. No relationship could be demonstrated between knee pain and joint laxity.