Adiposity and the risk of rheumatoid arthritis: a systematic review and meta-analysis of cohort studies

Tomoya Ohno,Dagfinn Aune,Alicia K Heath

doi:10.1038/s41598-020-71676-6

Abstract

Several studies have investigated associations between overweight/obesity and risk of developing rheumatoid arthritis, however, the evidence is not entirely consistent, and previous meta-analyses mainly included case–control studies, which can be affected by various biases. We therefore conducted a systematic review and meta-analysis of cohort studies on adiposity and risk of rheumatoid arthritis. Relevant studies were identified by searching PubMed and Embase databases. Random effects models were used to estimate summary relative risks (RRs) and 95% confidence intervals (CIs) for rheumatoid arthritis in relation to different measures of adiposity. Thirteen cohort studies (10 publications) were included. The summary RR per 5 kg/m2 increase in body mass index (BMI) was 1.11 (95% CI 1.05–1.18, I2 = 50%), but the association was restricted to women (1.15, 95% CI 1.08–1.21, I2 = 17%) and not observed in men (0.89, 95% CI 0.73–1.09, I2 = 58%). The summary RR per 5 kg/m2 increment in BMI at age 18 years was 1.17 (95% CI 1.01–1.36, I2 = 26%, n = 3), and per 10 cm increase in waist circumference was 1.13 (95% CI 1.02–1.25, I2 = 44%, n = 2). Higher BMI in middle age, BMI at age 18 years, and waist circumference were associated with increased rheumatoid arthritis risk, suggesting adiposity could be targeted for primary prevention.

Highlights

Several studies have investigated associations between overweight/obesity and risk of developing rheumatoid arthritis, the evidence is not entirely consistent, and previous meta-analyses mainly included case–control studies, which can be affected by various biases
The positive association between body mass index (BMI) in middle age and rheumatoid arthritis was restricted to women, and no clear association was observed in men; this could be due to an interaction with hormone-related factors or other sex-specific exposures, which may contribute to the higher prevalence of rheumatoid arthritis in w omen[26]
This study confirms a positive association between levels of adiposity and the risk of developing rheumatoid arthritis

Summary

Introduction

Several studies have investigated associations between overweight/obesity and risk of developing rheumatoid arthritis, the evidence is not entirely consistent, and previous meta-analyses mainly included case–control studies, which can be affected by various biases. Prevalence rates of 0–3 cases per 1,000 persons have been reported in some areas in Africa, while rates in Northern and Western Europe are around 4–11 cases per 1,000 inhabitants, and in North America between 9 and 11 cases per 1,000 inhabitants[4] These geographical differences in the occurrence of rheumatoid arthritis may be attributed to various factors, including genetic factors, socioeconomic factors, access to health services, and lifestyle factors[6]. To provide a more comprehensive assessment, we conducted an updated systematic review and meta-analysis of cohort studies to clarify the strength and shape of the association between different measures of adiposity and the risk of developing rheumatoid arthritis

Methods

Results

Discussion

Conclusion