The aim of our systematic review and meta‐analysis was to investigate whether overweight/obesity are associated with higher disease activity measures in axial spondyloarthritis (axSpA) patients.

MEDLINE, PubMed and Web of Science were searched using key terms corresponding to population (axSpA), exposure (overweight/obesity) and outcome (Bath Ankylosing Spondylitis Disease Activity Index, BASDAI; Ankylosing spondylitis disease activity score, ASDAS). Predefined inclusion criteria were: 1) adult axSpA patients 2) exposure classified according to Body Mass Index‐BMI‐; 3) BASDAI/ASDAS reported for each BMI group; 4) observational studies. 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 mean difference (MD) in BASDAI and ASDAS between BMI groups, with 95% confidence intervals (95%CI).

Ten 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/overweight patients was ‐0.09 (95%CI:‐0.33,0.15, p=0.45) and MD between normal BMI/obese patients was ‐0.78 (95%CI:‐1.07,‐0.48, p<0.0001). As for ASDAS, the MD between normal BMI/overweight patients was ‐0.02 (95%CI:‐0.19,0.15, p=0.79) and MD between normal BMI/obese patients was (‐0.42; 95%CI:‐0.60,‐0.23, p<0.0001).

Overweight and obese axSpA patients tend to present higher disease activity scores compared to normal BMI patients. This difference seems to be clinically meaningful only for the comparison between obese and normal BMI patients, and more for BASDAI than ASDAS.