Figure 3
Association of age of the study subjects with the benefit of zinc supplementation. (A) Results from restricted meta-analysis for each month of age (x-axis). Restricted meta-analysis was conducted for each month of age by including only those studies in which the range of age of the study subjects straddled the selected month of age. Left y-axis (green) shows the relative risk for incidence of diarrhea while the right y-axis (grey) shows the number of studies included in meta-analysis (B) Meta-regression. In this analysis the mid-point of the age range for each study was meta-regressed onto the relative risk of observed diarrheal incidence in that study. Each circle represents a trial - the diameter of a circle is proportional to the standard error in that study. Dark green line is the predicted regression line. Meta-regression on this variable indicated that accounting for age would reduce the I2 statistic by 6.3%. Pslope indicates the significance value for the test of a two-tailed null hypothesis that the slope of the regression line is zero.