Published online Jul 27, 2020. doi: 10.4254/wjh.v12.i7.389
Peer-review started: March 30, 2020
First decision: April 22, 2020
Revised: June 4, 2020
Accepted: June 10, 2020
Article in press: June 10, 2020
Published online: July 27, 2020
Processing time: 114 Days and 15.8 Hours
Zinc is an essential trace element integral to many cellular and immune functions. Zinc deficiency is highly prevalent in patients with cirrhosis and related to disease severity.
Zinc supplementation has been used to treat complications of cirrhosis including hepatic encephalopathy. However, it is unknown whether zinc supplementation in patients with cirrhosis results in a change in the risk of progression of cirrhosis or death.
This study aimed to evaluate whether zinc supplementation improves clinical outcomes and long-term survival in patients with cirrhosis.
A systematic review was performed including all studies in Medline, Embase or Cochrane database with inclusion criteria of adult human studies, comparing zinc supplementation of at least 28 d with standard care or placebo in patients with cirrhosis. Mortality and clinical severity score data were extracted. Random effects meta-analyses determined risk of mortality in patients receiving zinc supplementation versus comparator at 6 mo and 2 years. Risk of bias was assessed using the National Institutes of Health quality assessment tool.
Seven hundred and twelve articles were identified of which four were eligible. Zinc formulations and doses varied for different intervention periods in patients with differing etiology and severity of cirrhosis. Two studies were considered to be at high risk of bias. There was no significant difference in 6-mo mortality between patients treated with zinc versus controls. Changes in severity scores were not reported in any study.
Findings are limited by the small number of eligible studies and significant heterogeneity in intervention and patient population. Zinc supplementation is not statistically associated with reduced mortality or improved long term outcome in patients with cirrhosis.
There is substantial heterogeneity in study design, inclusion criteria and primary outcome. The difference in etiology and severity of liver cirrhosis also make the effect of zinc supplementation difficult to interpret. Further well-designed prospective studies are required to determine whether zinc supplementation improves long-term clinical outcome in patients with cirrhosis.