SAT0058 AGE DEPENDENT EFFECTS OF BODY MASS INDEX AND SMOKING ON THE RISK OF RHEUMATOID ARTHRITIS IN MEN – RESULTS FROM A NESTED CASE CONTROL STUDY

Abstract

Background:As rheumatoid arthritis (RA) is more common in women compared to men, most studies of disease predictors have mainly included women, and data on risk factors in men are limited. Smoking is an established predictor of RA. A negative association between body mass index (BMI) and the risk of RA in men has been reported from several studies of Scandinavian populations.Objectives:To investigate whether the impact of smoking and BMI on the risk of subsequent development of RA in men differs by age.Methods:A total of 22 444 men from a defined catchment area were included in a Preventive Medicine Program (PMP). Height and weight were measured as part of the health survey, and BMI was calculated as weight (in kg)/height (in m2). Information on smoking was obtained using a structured self-administered questionnaire. Normal BMI, overweight and obesity was defined according to the WHO criteria. From this population, we identified individuals who developed RA after inclusion by linking the PMP register to the local community based RA register and to local and national patient administrative databases. In a structured review of the medical records, patients were classified according to the 1987 ACR criteria for RA. Four controls for each validated case, matched for sex, year of birth and year of screening, who were alive and free of RA when the index person was diagnosed with RA, were selected from the PMP register. The impact of BMI category and smoking on the risk of RA was examined in multivariable conditional logistic regression models, stratified by age at inclusion in the health survey (above vs below the median).Results:A total of 151 men were diagnosed with RA and fulfilled the ACR criteria after inclusion in the PMP (median time to diagnosis 13 years, interquartile range 9-19; 76 % rheumatoid factor positive at diagnosis). These pre-RA cases were compared to 604 matched controls. Among men aged >46 years, overweight/obesity was associated with a significantly reduced risk of subsequent RA (odds ratio (OR) 0.40; 95 % confidence interval (CI) 0.21-0.76, adjusted for smoking), whereas there was no such association in younger men (adjusted OR 0.75 (95% CI 0.42-1.36). Smoking was a significant predictor of RA in men aged >46 years (Table 1). There was a similar trend in those aged ≤46 years, but it did not reach statistical significance (Table 1).Conclusion:Overweight/obesity was associated with a reduced risk of subsequent RA in men aged >46 years. The relative importance of life style factors for the risk of RA may be greater in older men compared to younger.Disclosure of Interests:Carl Turesson Grant/research support from: Unrestricted grant from Bristol-Myers Squibb, Consultant of: Roche, Speakers bureau: Abbvie, Bristol Myers-Squibb, Pfizer, Roche, Ulf Bergström: None declared, Mitra Linnerud Keshavarz: None declared, Jan-Åke Nilsson: None declared, Lennart T.H. Jacobsson Consultant of: AbbVie, Eli Lilly, Janssen, Novartis and Pfizer