Extra-articular Rheumatoid Arthritis Risk Factors and Consequences

Sammanfattning: Rheumatoid arthritis (RA) is a systemic disease not only restricted to the joints, but can also be associated with the development of extra-articular manifestations. Extra-articular RA (ExRA) is of clinical importance because of the associated morbidity and increased risk of premature mortality compared with RA patients in general. The aims of this work were to identify patients with ExRA in early RA cohorts, to find risk factors for ExRA and poor outcome, and to study consequences of ExRA. Two community based cohorts, the BARFOT cohort and the Malmö RA cohort, were studied. The BARFOT cohort was an inception cohort, which was followed according to a structured protocol. An unselected population of RA outpatients more closely reflects the actual appearance of ExRA in a RA population. All patients fulfilled the 1987 ACR classification criteria for RA and severe ExRA was identified according to prespecified definitions (the Malmö criteria for ExRA). In the first paper the prevalence of rheumatoid nodules (RN) at early RA diagnosis was 7% and there was a strong association between smoking and RN, but only among those with antibodies to rheumatoid factor (RF). In the second paper risk factors for severe ExRA were investigated. High levels of disease activity and disability during the first 2 years after RA diagnosis, smoking and positive RF were predictors. In the third paper, the relation between RN at early RA diagnosis and joint damage was investigated. RN was a predictor of radiographic progression of joint destruction over 5 years. However, only antibodies to cyclic citrullinated peptides and presence of erosive disease at RA diagnosis were independently associated with radiographic progression. In the fourth paper the incidence of severe ExRA after treatment with the first TNF-inhibitor was studied. A lower incidence of ExRA was found in patients treated with TNF-inhibitors as compared to those not treated with TNF-inhibitors, although the differences did not reach statistical significance. In conclusion, data from these studies suggest the following risk factors for ExRA: Smoking, high disease activity and disability burden and positive RF. The presence of RN at RA diagnosis was associated with radiographic progression. Treatment with TNF-inhibitors may decrease the incidence of ExRA.