The serum level of Dickkopf-1 in patients with rheumatoid arthritis: A systematic review and meta-analysis

Objective: Dickkopf-1 (DKK-1) is an endogenous inhibitor of canonical Wnt pathway that was implicated in the pathogenesis of rheumatoid arthritis (RA), but the serum levels of DKK-1 in RA were inconsistent among studies. Therefore, we conducted a meta-analysis to systematically evaluate the relationship between serum DKK-1 levels and RA. Methods: PubMed, Web of Science and Cochrane Library were comprehensively retrieved till 1 January 2018 for pertinent studies. The pooled standard mean differences (SMDs) of serum DKK-1 levels were calculated according to the random effects model. Results: Nine original studies containing 1305 RA patients and 504 healthy controls were included in the meta analysis. The pooled SMD of serum DKK-1 between RA patients and healthy controls was 0.79 (95% CI = 0.11 to 1.48, Z = 2.28 and P = 0.023), indicating a significantly higher serum level of DKK-1 in RA patients. Conclusion: Serum level of DKK-1 is elevated in patients with RA compared to healthy controls, suggesting an important role of DKK-1 in the pathogenesis and treatment of RA.