A comparison of the clinical features of hospital out-patients with rheumatoid disease and osteoarthritis in Pakistan and England.

Several studies have demonstrated differences between ethnic groups in the severity and pattern of rheumatoid arthritis (RA) and osteoarthritis (OA). The current investigation compared RA and OA in Pakistani and British White Caucasian out-patients in two teaching hospitals. There were 88 RA patients in each setting, matched for age, gender and disease duration. The pattern of OA was sought by recording the details of 44 consecutive new referrals to each clinic. Amongst the RA patients, joint deformity and tenderness were similar, but disability was more severe, ESR higher, anaemia more pronounced and RA latex more often positive amongst the Pakistani patients. X-ray damage was more pronounced amongst the British patients, especially in the feet. The British were also more likely to have rheumatoid nodules and to have undergone disease-modifying treatment or joint surgery. The paradox of more severe indices of disease activity and disability with less X-ray erosion in hands and feet might be explained by the impact of treatment on joint inflammation and the beneficial influence of surgery on disability in the British. The worse X-ray scores in the White Caucasians might indicate a genetic predisposition to radiologically more severe disease. The age of the British OA patients was significantly higher, but this is unlikely to have influenced the striking disparity in the frequency of isolated knee OA, which was significantly greater in the Pakistani patients. Comparison with age- and sex-matched healthy Pakistani subjects suggested that susceptibility to knee OA was strongly associated with body weight, but not with knee bending at prayer or with joint laxity. Amongst the Pakistanis, Heberden nodes, hip involvement and evidence of generalized OA were significantly less, but these observations may have been due to their younger age. The study confirmed differences in the clinical presentation of both RA and OA amongst patients in Pakistan compared with White Caucasians in Britain. Several confounding factors, such as patient recruitment, culture, treatment and age, may have influenced the results, but it remains likely that genetic factors are important.