Age-based targeting of biannual azithromycin distribution for child survival in Niger: an adaptive cluster-randomized trial protocol (AVENIR)

Table 3 Detectable effect sizes and assumptions used in sample size calculations for mortality and resistance primary outcomes for the AVENIR trial

Trial	Outcome	Comparison	Power	Alpha	Baseline^a,b	SD or ICC^b	Number of communities per arm	Relative effect size	Absolute effect size
Mortality^c	Mortality in 1–59-month group	Azithromycin 1–59 vs placebo	80%	0.05	27 deaths per 1000 person-years	0.019	1116	10%	2.7 per 1000 person-years
	Mortality in 1–11-month group	Azithromycin 1–11 vs placebo	80%	0.05 (if 1–59 group P < 0.05)	45 deaths per 1000 person-years	0.068	1116	19%	8.8 deaths per 1000 person-years
	Mortality in the 12–59-month group	Azithromycin 1–11 vs azithromycin 1–59	80%	0.05 (if 1–11 group P < 0.05)	24 deaths per 1000 person-years	0.018	1116	11%	2.7 deaths per 1000 person-years
Resistance^d	Prevalence of genetic determinants, NP swabs in 1–59-month group	Azithromycin 1–11 vs placebo Azithromycin 1–59 vs placebo Azithromycin 1–11 vs 1–59	80%	0.05/2	30%	0.045	20	43%	13%
Resistance^d	Load of genetic determinants, rectal swabs in 1–59-month group^e	Azithromycin 1–11 vs placebo Azithromycin 1–59 vs placebo Azithromycin 1–11 vs 1–59	80%	0.05/2	2.13	0.02	20	70%	0.74

ICC intra-class correlation coefficient, SD standard deviation
^a Refers to baseline mortality rate for mortality outcomes, and baseline prevalence or load of genetic determinants of macrolide
resistance for resistance outcomes.
^b Estimated using data from the MORDOR Niger trial, SD reported for mortality rates and ICC for resistance
^c Calculations based on standard Z-test formula for power
^d Calculations based on Eqs. 7.11 and 7.12 for prevalence and load, respectively [19].
^e Load of genetic determinants of resistance presented on the log2 scale

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