SAT0087 Does the season of symptom onset influence the severity of radiographic joint destruction in rheumatoid arthritis

Background Several season-associated environmental factors have been related to the onset of rheumatoid arthritis (RA) and the severity of joint complaints. A recent study on early arthritis demonstrated that onset of arthritis symptoms during Winter or Spring was associated with more radiographic joint damage after one year.(1) Objectives To evaluate the influence of the season of symptom onset on long-term radiographic progression. Methods 688 RA-patients, included in the Leiden Early Arthritis Clinic (EAC) and 830 RA-patients included in the Swedish BARFOT-study were studied. During a follow-up period of 7 and 5 years, respectively, repeated radiological measurements were performed and scored for joint damage according to the van der Heijde modification of the Sharp method. The majority of these patients were recruited in an era when early aggressive treatment was not yet the standard. Seasons were defined meteorologically, meaning that Winter ranges from December 1-February 28, Spring from March 1 – May 31, Summer from June 1 – August 31, and Autumn from September 1 – November 30. Results In both cohorts, the proportion of RA-patients that had their symptom onset in Winter tended to be larger than that for the other seasons. This was significant in the BARFOT-cohort (p=0.005), but not in the Leiden EAC. Nonetheless, the radiological progression rates over time were similar in the four seasonal groups in both cohorts (p=0.29 in the Leiden RA-cohort and p=0.46 in the BARFOT RA-cohort). Conclusions In two large inception cohorts, we did not find evidence that meteorologically defined seasons of symptom onset have any relevant influence on the severity of joint damage in RA.Therefore, this study does not support the hypothesis that the severity of joint damage of RA is influenced by season related environmental factors such as infectious pathogens. References Mouterde G, Lukas C, Logeart I, Flipo RM, Rincheval N, Daures JP et al. Predictors of radiographic progression in the ESPOIR cohort: the season of first symptoms may influence the short-term outcome in early arthritis. Ann Rheum Dis 2011; 70(7):1251-6. Disclosure of Interest None Declared