Common trace metals in rheumatoid arthritis: A systematic review and meta-analysis

Environmental risk factors regrading rheumatoid arthritis (RA) have not been explored extensively. Selenium (Se), zinc (Zn) and copper (Cu) nutrients were reported to associate with RA, but the results were inconsistent. Therefore, we conduct present study to meta-analyze the relationship between serum Se, Zn and Cu and RA and review the potential mechanisms.

PubMed, Web of Science and Cochrane Library were comprehensively searched till October 1, 2018 for pertinent studies. Standard mean differences (SMDs) and 95% confident intervals (CIs) were calculated according to random effects model.

Finally 41 literatures were included. Meta-analysis of 16 studies involving 806 RA patients and 959 health controls showed that serum Se (SMD = -1.04, 95% CI = -1.58 to -0.50) was decreased in RA patients, and 23 literatures with 1398 patients and 1299 controls reported serum Zn (SMD = -1.20, 95% CI = -1.74 to -0.67) was decreased. But serum Cu (SMD = 1.26, 95% CI = 0.63 to -1.89) was increased with 26 studies including 1723 patients and 1451 controls. Meta-regression reported that steroid use was positively related to serum level of Se in RA (β = 0.041, 95% CI = 0.002 to 0.079). Differences in serum Se, Zn and Cu between rheumatoid arthritis patients and controls were all related with the geographical distribution.

Patients with RA have significant decreased serum Se and Zn and increased serum Cu than health controls, suggesting potential roles of Se, Zn and Cu in the pathogenesis of RA. Patients and rheumatologist should give enough attention to the monitor of these elements during follow up.