To determine the prevalence of rheumatic diseases in Han Chinese in north and south China.
Samples of 4192 adults in the Beijing (north) and 5057 in the Shantou (south) areas, based on village administration registers, were studied. The same questionnaire was administered by doctors who then examined those with rheumatic symptoms. One observer (QYZ) took part in both studies.
The prevalence of definite rheumatoid arthritis (RA) was 0.34% (95% CI; 0.20-0.51) in the north and 0.32% (0.16-0.47) in the south. Ankylosing spondylitis (AS) was noted in 0.26% of both samples (95% CI; 0.11-0.42 north and 0.14-0.40 south). Only 3 cases of systemic lupus erythematosus (SLE) in the north and one in the south were identified. General rheumatic pain was reported more frequently in the north. Lumbar problems were recorded on examination 5 times more frequently in the north than in the south [men, 25%:5.3%; women 38%:6.5%] and knee problems 10 times more frequently [men, 24%:1.8%; women, 36%:3.4%] in the north. The difference was greatest in the 55 to 64 year age group.
The prevalence of RA was similar to that in other rural populations and Japan, but only half that reported from other industrialized communities. The prevalence of AS was similar to that in most Caucasian populations. SLE was too infrequent to establish a prevalence with confidence, but did not differ from that in other populations. A study is planned in the south to assess the contribution of interobserver error and/or differences in cultural response to the north/south differences observed in the prevalence of general rheumatic symptoms and back pain.