OP0269 Obesity and the Risk for Development of Rheumatoid Arthritis – Results from a Population-Based Nested Case-Control Study

BackgroundStudies on obesity and the risk for development of rheumatoid arthritis (RA) have shown diverse results, and studies with prospectively collected data are few.ObjectivesTo evaluate the association between obesity and subsequent risk for development of RA.MethodsIn 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.ResultsThe 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).Table 1.Conditional logistic regression models with case-controls sets matched for age, sex, area of inhabitance, cohort and year of visit in the cohort, assessing odds ratios for the risk for development of RA associated with cathegories based on body mass indexCases (n=548)Controls (n=1,641)OR1 (95% CI)OR2 (95% CI)AllNormal weight215 (39%)752 (46%)ReferenceReferenceUnderweight6 (1%)13 (1%)1.6 (0.6–4.2)1.3 (0.5–3.6)Overweight230 (42%)648 (40%)1.3 (1.0–1.6)1.3 (1.0–1.6)Obese97 (18%)228 (14%)1.5 (1.1–2.0)1.4 (1.1–1.9)MenNormal weight53 (30%)193 (37%)ReferenceReferenceUnderweight02 (0.4%)––Overweight91 (52%)259 (50%)1.3 (0.9–1.9)1.5 (1.0–2.3)Obese31 (18%)67 (13%)1.7 (1.0–2.9)1.9 (1.1–3.5)WomenNormal weight162 (43%)559 (50%)ReferenceReferenceUnderweight6 (2%)11 (1%)1.8 (0.7–5.0)