When a patient's first symptoms of rheumatoid arthritis (RA) occur in winter, the severity of their RA (as measured by the modified Total Sharp Score, mTSS, an assessment of erosion and joint space narrowing) was rated more severe at six months, when compared to patients whose RA first became symptomatic in summer (Odds Ratio (OR) =2.82 [1.14;7], p=0.0255). Furthermore, RA patients with their first symptoms in spring showed poorer radiographic outcome compared to summer-onset patients (OR=2.83 [1.10;7.37], p=0.0322), according to the results of a new study presented today at EULAR 2009, the Annual Congress of the European League Against Rheumatism in Copenhagen, Denmark.
Similarly, patients' mTSS after six months was worse if their first symptoms had occurred in winter (OR=2.61 [1.20; 5.71], p=0.0158) or in spring (OR=2.63 [1.13; 6.14], p=0.0025) versus autumn as the reference season. This effect was not however observed at 12 month follow up, which the study authors suggest could suggest that these initial environmental factors exert less of an effect on longer term radiographic progression.
Dr Gaël Mouterde, Immuno-Rheumatology Department, Lapeyronie Hospital, Montpellier, France who led the research, said: "During our study of predictors of radiographic progression, we have unveiled a distinct relationship between RA progression and seasonal onset and postulate that this could be as a result of either a vitamin D deficiency or environmental factors, such as winter viruses, influencing protein citrullination. Anti-citrullinated protein antibodies (ACPAs) are often found in the immune systems of RA patients. This finding may assist towards the identification of RA patients at a higher risk of developing structural damage, in order to propose early intensive therapy and minimise disease progression."