Table 2. Effect of zinc on incidence of diarrhoea and acute lower respiratory infection Disease Intervention Comparison Rate ratio (95% CI)* Difference in mean rates (95% CI) Diarrhoea:   Periods observed 20 699 21 089   Periods with diarrhoea  3 278  3 947   Unadjusted incidence (%) 15.8 18.7 0.85 (0.76 to 0.96) 2.9 (0.8 to 5.1) Acute lower respiratory infection:   Periods observed 20 699 21 089   Periods with acute lower respiratory infection  1 543  1 700   Unadjusted incidence (%) 7.5 8.1 0.93 (0.78 to 1.10) 0.7 (0.7 to 2.0) * Based on individual level analysis using random effect Poisson regression model. Adjusted for child's age, sex, and birth order, mother's education, household homestead land size, baseline cluster level diarrhoea admission rates, and intra-cluster correlation. Based on cluster level t test analysis. Differences in mean rates expressed per 100 child years of observation. Adjusted for child's age, sex, and birth order, mother's education, household homestead land size, and baseline cluster level diarrhoea admission rates.