To evaluate the relationship between miR-146a levels and rheumatoid arthritis (RA), and the correlation with RA activity.
For the meta-analysis, we searched the PubMed, MEDLINE, EMBASE and Cochrane databases, comparing miR-146a levels in patients with RA and controls, and correlation coefficients between miR-146a levels and Disease Activity Score for 28 joints (DAS28) and erythrocyte sedimentation rate (ESR) in patients with RA.
Fourteen studies, totaling 683 patients with RA and 477 controls, were available. miR-146a levels were significantly higher in the RA group than in the control group (standardized mean difference [SMD] = 0.546, 95% CI = 0.033-1.059, P = 0.037). Stratification by adjustment for age and/or sex revealed significantly higher miR-146a levels in the adjusted, but not in the non-adjusted group (SMD = 0.747, 95% CI = 0.094-1.400, P = 0.025; SMD = 0.431, 95% CI = -0.430-1.291, P = 0.326, respectively). Stratification by sample size showed significantly higher miR-146a levels in RA groups of large sample sizes (N ≥ 50), but not in those of small size. miR-146a levels in synovial tissue/fluid were significantly higher in the RA group than in the OA group (SMD = 1.305, 95% CI = 1010-1.639, P < 0.001). A significant positive correlation was found between miR-146a levels and ESR (correlation coefficient = 0.534, 95% CI = 0.029-0.822, P = 0.039).
Circulating and synovial tissue/fluid miR-146a levels are high in patients with RA, and circulating miR-146a levels positively correlate with ESR.