Efficacy of Mass Azithromycin Distribution for Reducing Childhood Mortality Across Geographic Regions

Abstract

Mass azithromycin distribution has been shown to reduce all-cause mortality in preschool children in sub-Saharan Africa. However, substantial heterogeneity in the apparent effect has been noted across geographic settings, suggesting a greater relative benefit in higher mortality settings. Here, we evaluated the relationship between the underlying mortality rate and the efficacy of azithromycin for the prevention of child mortality using data from multiple sites in Ethiopia, Malawi, Niger, and Tanzania. Between regions, we find no strong evidence of effect modification of the efficacy of azithromycin distribution for the prevention of child mortality by the underlying mortality rate (P = 0.12), although a modest effect is consistent with our findings. Higher mortality settings could be prioritized, however, because of the larger number of deaths which could be averted with azithromycin distribution.

Figure 1.

Azithromycin effect vs. mortality in three studies. The effect of azithromycin (vertical axis) is expressed as the natural logarithm of the relative rate (with larger values indicating larger benefit) in a geographic zone (see text for details). Mortality is depicted as the rate (azithromycin and placebo communities) in the given geographic zone, transformed to be comparable to an under-five mortality rate (per 1,000). Conversion to an approximate under-five mortality rate u was accomplished by u = Yr + n, where Y is the number of years of observation in each study, r is the estimated annual mortality rate in the given zone, and n is the reported neonatal mortality rate for the given nation (Ethiopia, Tanzania, Malawi, or Niger). Neonatal mortality rates from the World Bank were used in this calculation (https://data.worldbank.org/indicator/SP.DYN.IMRT.IN, accessed 22 December 2018). Statistical inference was not based on these neonatal mortality rates. Zone-specific neonatal mortality rates are not available. The black line and gray bands represent a descripive lowess smoothed and standard error.