Session Title: Rheumatoid Arthritis - Human Etiology and Pathogenesis
Session Type: Abstract Submissions (ACR)
Background/Purpose There are diverging results on the relation between body mass index (BMI) and risk of rheumatoid arthritis (RA). Several studies have reported different patterns in men and women. Our purpose was to investigate the impact of overweight and obesity on the risk of RA in a prospective study.
Methods Between 1991 and 1996, 30447 subjects (12121 men; 18326 women) were included in a population based health survey. Height and weight were measured, and life style factors were assessed using a questionnaire. From this population, we identified individuals who developed RA after inclusion by linkage to 4 different RA registers. In a structured review of the medical records, patients were classified according to the 1987 American College of Rheumatology 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 health survey database. The impact of overweight or obesity (BMI > 25 kg/m2) compared to normal BMI (18.5-25 kg/m2) on the risk of RA was examined in conditional logistic regression models, stratified by sex.
Results A total of 172 patients (36 men/136 women, mean age at RA diagnosis 63 years) were diagnosed with RA after inclusion in the health survey. The median time from inclusion to RA diagnosis was 5 years (range 1–13). A total of 51 % of cases and controls combined were overweight or obese. Being overweight or obese at inclusion in the health survey was associated with a reduced risk of subsequent development of RA in men [odds ratio (OR) 0.33; 95 % confidence interval (CI) 0.14-0.76], but not in women (OR 1.01; 95 % CI 0.65-1.54). Men who fulfilled the WHO definition for obesity (BMI >30 kg/m2) had a significantly decreased risk of RA compared to those with normal BMI (OR 0.08; 95 % CI 0.01-0.67), and there was a similar trend for those with overweight (BMI 25-30 kg/m2) (OR 0.42; 95 % CI 0.17-1.00). Smoking was a significant predictor of RA in both sexes, and negatively associated with overweight/obesity in men. The estimated impact of overweight/obesity on the risk of RA in men was similar in analyses adjusted for smoking (OR 0.37; 95 % CI 0.16-0.87) and analyses adjusted for smoking, level of education and alcohol use (OR 0.37; 95 % CI 0.13-1.04). In women, overweight/obesity had no effect on the risk of RA in multivariate analyses.
Conclusion Being overweight or obese was associated with a reduced risk of future RA in men. This pattern did not appear to be explained by differences in smoking, education or alcohol use. There was no such association in women. Factors related to adipose tissue may contribute to mechanisms that are protective from RA in men.
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ACR Meeting Abstracts - https://acrabstracts.org/abstract/overweight-and-obesity-are-associated-with-reduced-risk-of-rheumatoid-arthritis-in-men-but-not-in-women/