Published: July 2012

In a nutshell The Program: Short term zinc supplementation to treat diarrhea episodes in children under five, often administered in conjunction with oral rehydration solution.

Short term zinc supplementation to treat diarrhea episodes in children under five, often administered in conjunction with oral rehydration solution. Track Record: Evidence from numerous randomized controlled trials (RCTs) indicates that zinc supplements moderately decrease the duration of acute and persistent diarrhea. One RCT has found that they cause a large and statistically significant reduction in mortality, though we have significant reservations about this study. Deployment of this intervention so far has mostly been limited to small-scale studies.

Evidence from numerous randomized controlled trials (RCTs) indicates that zinc supplements moderately decrease the duration of acute and persistent diarrhea. One RCT has found that they cause a large and statistically significant reduction in mortality, though we have significant reservations about this study. Deployment of this intervention so far has mostly been limited to small-scale studies. Cost-Effectiveness: We do not have sufficient information to create a credible cost-effectiveness estimate. The one published cost-effectiveness estimate suggests that zinc supplementation could be amongst the most cost-effective programs. However, we believe this estimate is likely to overstate the cost-effectiveness of zinc supplementation in multiple ways.

Basics of the program

What is the program? What problem does it target?

Therapeutic zinc supplementation is a program aimed at treating diarrhea in children under the age of five, one of the leading causes of death in children in the developing world. The World Health Organization and UNICEF recommend that children with diarrhea take zinc supplementation for 10-14 days along with oral rehydration solution.

Program track record

Micro evidence: Has this program been rigorously evaluated and shown to work?

Diarrhea duration

In the Cochrane Review on zinc supplementation for treating diarrhea in children under five years old, Lazzerini and Ronfani review the results of 24 randomized, placebo-controlled trials, finding that therapeutic zinc supplementation may cause a moderate reduction in the duration of diarrhea. In particular, they find that oral zinc treatment reduced the average duration of diarrhea in children with acute diarrhea by 12 hours (against a control average duration ranging from 41 to 170 hours), and reduced the average duration of diarrhea in children with persistent diarrhea by 15.8 hours (against a control average duration ranging from 84 to 168 hours); both of these results were statistically significant at the conventional 95% level. Results for the effectiveness of zinc in reducing the severity of diarrhea, as opposed to its duration, were inconsistent.

Mortality

Of the 24 studies included in the Cochrane Review, only seven reported mortality results, of which four had no mortality in either the control or treatment groups. Amongst those studies that observed some mortality, there were a total of three deaths in the zinc treatment groups and eight deaths in the placebo groups, too few for statistical significance.

However, Lazzerini and Ronfani exclude two large cluster-randomized controlled experiments because their control groups did not receive placebos. One of these studies, conducted by Baqui et al. in Bangladesh, recorded 13 non-injury deaths in the treatment group, compared with 27 non-injury deaths amongst the control group. These deaths translate into a mortality rate of 2.22 per 1,000 per year for the treatment group and 4.49 per 1,000 per year for the control groups; controlling for age, sex, and a few other covariates, treatment is associated with a 51% decrease in the risk of non-injury mortality (with a 95% confidence interval stretching from 6% to 75%).