Background Studies on obesity and the risk for development of rheumatoid arthritis (RA) have shown diverse results, and studies with prospectively collected data are few.
Objectives To evaluate the association between obesity and subsequent risk for development of RA.
Methods In The Västerbotten Interventional Program (VIP) or/and The WHO project Multinational MONItoring of Trends and Determinants of CArdiovascular Disease (MONICA) 1985-2013 individuals with RA (year of onset of symptoms 1989-2013) were identified (cases, n=550), and data from the latest visit antedating onset of RA symptoms were retrieved. From the same population-based, prospective cohorts 1650 controls, matched for age, sex, cohort, inclusion year, cohort and area of inhabitance (rural/urban) were randomly selected. Prospectively collected data on body mass index (BMI; weight/lenght2), smoking habits, and educational level was used in calculations of odds ratio; OR (95% confidence interval) in conditional logistical regression assessing associations between obesity and the risk for development of RA.
Results The cases (mean age at RA symptom onset 58 SD 11 years, 68% women) had been included in the cohorts (MONICA n=49, VIP n=501) at median 6.7 (IQR 6.4) years before the onset of symptoms of RA. Obesity (BMI≥30) was associated with an increased risk for RA development, OR 1.4 (1.1-1.9), compared to those with normal weight (BMI 18.5-25). The association was stronger in male subjects (Table 1). Stratifying the patients on age at onset of symptoms of RA the association between obesity and the risk of RA was only observed in the quartile with earliest disease debut, 32-50 years, OR for obesity vs. normal weight 1.9 (1.1-3.7).
Conclusions Obesity was independently associated with a modest increase in the risk for subsequent development of RA. This appeared to be relevant mainly for men and patients with RA disease onset at 50 years of age or earlier.
Disclosure of Interest None declared