Objectives: To determine the incidence of severe extra-articular rheumatoid arthritis (ExRA) in a community-based cohort of RA patients, and to evaluate whether treatment with tumour necrosis factor (TNF) inhibitors has any effect on the risk of ExRA.
Methods: In a review of clinical records from 1 July 1997 to 31 December 2004, severe ExRA manifestations were classified according to predefined criteria. Patients were censored at the development of ExRA, death, emigration, or 31 December 2004. Exposure to anti-TNF treatment has continuously and independently been recorded as part of a regional follow-up system.
Results: During treatment with TNF inhibitors, there were two patients with new onset of ExRA in 408 person-years at risk (pyr) [0.49/100 pyr, 95% confidence interval (CI) 0.06-1.77]. Among those without anti-TNF treatment there were 63 patients with ExRA in 5425 pyr (1.16/100 pyr, 95% CI 0.89-1.49). The relative risk comparing those treated to those not treated with TNF inhibitors was 0.42 (95% CI 0.10-1.73).
Conclusion: Our data show a lower incidence of ExRA in patients treated with TNF inhibitors but further studies with a larger sample size are needed for a more accurate estimate of the size of the effect.