Association between obesity types and anthropometric indices with rheumatoid arthritis disease

Obesity is one of the causes of onset and exacerbation of rheumatoid arthritis. However, limited studies have examined the association between body composition and severity of disease. The aim of this study was to evaluate the association between severity of rheumatoid arthritis with various types of obesity and the comparison of anthropometric indices between patients with rheumatoid arthritis and healthy subjects.

This case-control study was conducted on 95 patients (48.8±10.4 years) with rheumatoid arthritis as a case group and 95 healthy people (46±9.3 years) as a control group carried in Golestan Hospital, Ahvaz, Iran, from April 2016 to February 2017. Weight, height, waist circumference (WC), hip circumference (HC) and body fat percentage (BFP) were measured. The anthropometric indices were calculated. The disease severity was calculated according to disease activity score 28 (DAS28).

There was no significant difference between two groups regarding their gender ratio (1:1), age (P=0.16) and height (P=0.58). The weight, body mass index (BMI), body fat (BF), WC, HC, waist-to-hip ratio (WHR), waist-to-height ratio (WHtR) and other obesity indices include a body shape index (ABSI), body adiposity index (BAI), abdominal volume index (AVI), body surface area (BSA) and Conicity index (CI) in patients with rheumatoid arthritis are significantly higher than healthy subjects (P<0.05). No difference in fat free mass was observed between two groups. Waist to height ratio and BAI compared with other indicators had the highest correlation with the DAS28 score. In addition, prevalence of obesity by waist circumference (82% vs. 61%), obesity by BMI (47% vs. 33%), and obesity by BFP (91% vs. 83%) was higher in patients with rheumatoid arthritis than healthy subjects. The risk of rheumatoid arthritis in people with central obesity by waist circumference (OR=2.92, 95% CI 1.50-5.70) was greater than obesity defined by BMI (OR=1.77, 95% CI 0.98-3.18) or BFP (OR=2.37, 95% CI 1.01-5.53).

The results of present study indicate association of rheumatoid arthritis disease severity with obesity types (especially central obesity) and anthropometric indices.