A study found that about 33% of cases of rheumatoid arthritis (RA) are attributable to modifiable lifestyle factors—in particular smoking, overweight or obesity, and low alcohol consumption.
The researchers collected data from the National Health and Nutrition Examination Survey as well as studies identified through a search of PubMed and Web of Science up to March 31, 2019. Studies eligible for inclusion were epidemiological studies reporting the correlation between non-genetic risk factors and RA in U.S. adults. Relative risk (RR) value and confidence interval (CI) were pooled by meta-analysis; the prevalence and RR data were used to determine the population attributable fraction (PAF).
The weighted percentage of former smokers was 24.84%; of current smokers, 23.93%; and overweight or obese people, 63.97%; average weekly alcohol consumption was 51.34 g. The meta-analysis revealed an increased risk for RA in former smokers (RR, 1.22; 95% CI, 1.10-1.36) and current smokers (RR, 1.47; 95% CI, 1.29-1.68). The risk of RA in people who were overweight and obese was 1.27-fold (95% CI, 1.09-1.48). For every 50 g of alcohol consumed each week, there was an 8% reduced risk for RA (95% CI, 0-16). The PAF value of smoking was 14% (95% CI, 8.13-23.33); excess body mass index, 14.73% (95% CI, 5.45-23.5); and low alcohol intake, 8.21% (95% CI, 0.31-16.39).
When adding the three factors together, smoking, overweight or obesity, and low level of alcohol consumption constituted 32.69% of cases of RA (95% CI, 13.41-50.96).
The study was published in BMJ Open.
“We estimated RA incident cases attributable to smoking, overweight or obesity and alcohol drinking, informing key intervention targets to reduce RA risk in the region. The effect of unselected risk factors on RA is still unknown. It is needed to continue more fundamental research on other lifestyle factors to illuminate the questions,” the researchers wrote in their conclusion.