Table 2 Assumptions, parameters, and sample size estimations for the longitudinal cohorts in Mali, Kenya, and Zambia
From: Attractive targeted sugar bait phase III trials in Kenya, Mali, and Zambia
Mali | Kenya | Zambia | |
|---|---|---|---|
Clusters per arm (overall) | 38 (76) | 35 (70) | 35 (70) |
Trial duration in calendar years (seasonality of FU) (total FU per participant time in months) | 2 years (8-month seasons) (16 months FU) | 2 years (12-month seasons) (24 months FU) | 2 years (6-month seasons) (12 months FU) |
α (type 1 error probability for 2-year trial) | 0.05 (Haybittle-Peto with one interim analysis) | 0.05 (Haybittle-Peto with two interim analyses at approx. 50% and 75%) | 0.05 (Haybittle-Peto with one interim analysis) |
Power | 88% | 80% | 80% |
Baseline incidence of clinical malaria in the target age group | 0.40 events per person year (based on 0.6 incident events during an 8-month malaria season) (5y–<15y) | 0.845 events per person year during a 12-m malaria transmission season (1y–<15y)a | 0.50 events per 6-month malaria season (Jan–Jun) (1y–<15y) |
Reduction in baseline incidence (incidence rate ratio = 0.70) | 30% | 30% | 30% |
Coefficient of variation | 0.40 | 0.40 | 0.40 |
Assumed loss of person-time, including true LTFU plus loss due to exclusion of person-time following each treatment with AL | 20% | 20% | 34% |
Total person-years required (number enrolled per cluster before loss to follow-up) | 3850 person-years (obtained by enrolling 38 individuals per cluster to account for loss to follow-up, followed for total of 16 months) | 1260 person-years (obtained by enrolling 13.5 individuals per cluster to account for loss to follow-up, followed for total of 24 months) | 1610 person-years (obtained by enrolling 35 individuals per cluster to account for loss to follow-up, followed for total of 12 months) |