Do Obesity and Overweight Influence Disease Activity Measures in Axial Spondyloarthritis? A Systematic Review and Meta-Analysis

Objective The aim of our systematic review and meta-analysis was to investigate whether overweight/obesity are associated with higher disease activity measures in patients with axial spondyloarthritis (SpA). Methods MEDLINE, PubMed, and Web of Science were searched using key terms corresponding to population (axial SpA patients), exposure (overweight/obesity), and outcome (Bath Ankylosing Spondylitis Disease Activity Index [BASDAI] and Ankylosing Spondylitis Disease Activity Score [ASDAS]). Predefined inclusion criteria were adult patients with axial SpA, exposure classified according to body mass index (BMI), BASDAI/ASDAS reported for each BMI group, and observational studies. The Newcastle-Ottawa Scale for cohort, cross-sectional, and case-control studies was used for quality check. Random-effects meta-analysis was used to pool results, which were expressed as the mean difference (MD) in BASDAI and ASDAS between BMI groups, with 95% confidence intervals (95% CIs). Results A total of 10 articles were included in the meta-analysis. The MD in BASDAI between normal BMI and overweight/obese patients was -0.38 (95% CI -0.56, -0.21; P < 0.0001); the MD in ASDAS between the same groups was -0.19 (95% CI -0.29, -0.09; P < 0.0001). The MD in BASDAI between normal BMI and overweight patients was -0.09 (95% CI -0.33, 0.15; P = 0.45), and the MD between normal BMI and obese patients was -0.78 (95% CI -1.07, -0.48; P < 0.0001). For ASDAS, the MD between normal BMI and overweight patients was -0.02 (95% CI -0.19, 0.15; P = 0.79), and the MD between normal BMI and obese patients was -0.42 (95% CI -0.60, -0.23; P < 0.0001). Conclusion Overweight and obese patients with axial SpA tend to present higher disease activity scores compared to patients with a normal BMI. This difference seems to be clinically meaningful only for the comparison between obese patients and patients with normal BMI, and more for BASDAI than ASDAS.