Published data regarding the association of leptin levels with rheumatoid arthritis (RA) are contradictory. To derive a more precise estimation of this relationship, a meta-analysis was performed.
Published literature from PubMed, Embase and Cochrane Library was obtained. Pooled standard mean difference (SMD) with 95 % confidence interval (CI) was calculated using fixed-effects or random-effect model analysis. Heterogeneity among studies was evaluated using the Cochran Q and I (2) statistics. The study quality was assessed by the Newcastle-Ottawa scale.
A total of 20 studies including 998 RA patients and 692 controls were finally included in the meta-analysis. Compared to healthy controls, RA patients had significantly higher leptin levels (SMD 1.19, 95 % CI 0.59-1.79). Subgroup analyses showed that region, race, age, body mass index (BMI), disease duration and disease activity were positively associated with plasma leptin levels in RA patients. Sensitivity analysis showed no significant change when any one study was excluded. Publication bias was also undetected.
The present meta-analysis suggested that leptin levels were higher in RA patients than those in healthy controls, which may be subject to different region, race, age, BMI, disease duration and disease activity.