Serum and Hair Zinc Levels in Patients with Endemic Osteochondropathy in China: A Meta-analysis

A large number of studies have shown growing interest in the zinc (Zn) levels of serum and hair samples collected from patients with Kashin-Beck disease (KBD), an endemic chronic osteochondral disease. However, inconsistent conclusions regarding the serum and hair Zn levels have been made. The aim of this study is to assess and to explore the change in serum and hair Zn levels among KBD patients. Multiple databases, including PubMed, Web of Science, Chinese National Knowledge Infrastructure (CNKI), Wanfang database and Technology of Chongqing (VIP), were carefully searched for available studies up to January 13, 2017 in this integrated analysis. Standard mean difference (SMD) with a 95% confidence interval (95% CI) was calculated using STATA 11.0. A total of 18 studies, involving 978 KBD cases and 1116 healthy controls, were collected in this analysis. Pooled analysis found the KBD patients had a higher hair Zn level and a lower serum Zn level than the healthy controls (hair Zn (mu g/g), SMD = 0.030, 95% CI = -0.315, 0.376; serum Zn (mg/L), SMD = -0.069, 95% CI = -0.924, 0.785). Meta-regression method and sensitivity analysis were utilized to analyze the heterogeneity of data. Positive correlations were separately identified between hair Zn level in KBD patients (r = 0.4639, P = 0.032) and controls (r = 0.4743, P = 0.012) and the survey year. No evidence of publication bias was observed. The available results suggest that increased hair Zn level and decreased serum Zn level are commonly found in KBD patients; however, the role of Zn in the etiology and pathogenesis of KBD could not yet be confirmed.