Sample size for anthropometric endpoints.
For this analysis, we estimated the minimum detectable effect on growth outcomes given the sample size that was determined for the trial’s primary endpoint, mortality by age 6 months. By the 6-month visit, there were 9,475 children measured in the azithromycin arm and 9,627 in the control arm. Assuming 9,475 children per group with 90% power with a two-sided alpha of 5%, we estimated the minimum detectable effect for LAZ, WLZ, and WAZ given the study’s empirical standard deviation for each outcome (LAZ SD = 1.15, WLZ SD = 1.19, WAZ SD = 1.05) adjusted for the correlation with baseline (LAZ r = 0.37, WLZ r = 0.20, WAZ r = 0.34). The minimum detectable effect sizes for this trial were LAZ = 0.05, WLZ = 0.06, and WAZ = 0.05.