To identify clinical and genetic risk factors for extra-articular manifestations of rheumatoid arthritis (ExRA).
ExRA patients were identified retrospectively using predefined criteria in two hospital-based cohorts of RA patients, and compared to non-extraarticular RA controls from one of the cohorts, matched for disease duration.
Forty-nine living and thirteen deceased cases of ExRA were identified. Extra-articular disease was predicted by the demonstration of antinuclear antibodies (Odds ratio (OR) 3.6; 95% CI: 1.4-9.1) and the presence of rheumatoid nodules within two years from RA diagnosis (OR 3.4; 95%, CI: 1.1-10.9) or at any time before ExRA onset (OR 2.8; 95% CI: 1.1-7.2). Male sex and rheumatoid factor did not affect the risk of ExRA. Although present in the majority of cases as well as controls, the disease associated HLA-DRB1 subtypes were not significant predictors of ExRA.
Extra-articular manifestations of rheumatoid arthritis in a hospital based population were predicted by antinuclear antibodies and rheumatoid nodules.