Task-shifting contraceptive implant removal to community health workers in Malawi: a target-trial emulation of method-continuation and unintended-pregnancy outcomes

Contraceptive implant discontinuation in Malawi is constrained by the concentration of removal skills among facility-based providers, and task-shifting removal to community health workers has been proposed as a remedy. The causal quantity of interest is the effect of community-based removal on method continuation and unintended pregnancy, but no randomised evidence exists and a trial is unlikely. the present analysis specifies a target-trial emulation for that question and characterises the operating characteristics of the before-after-control-impact design that would be used to evaluate a district-level task-shifting rollout. No observational data are used or claimed. Under a declared variance structure with between-cluster standard deviation 6.0, residual standard deviation 4.5 and intraclass correlation 0.64, power was estimated across 2000 replications per design cell for cluster counts of 8, 16, 24 and 32 and effects of 3, 5 and 8 percentage points. Fifty-two clusters are required for 80% power at a 5 percentage point effect. The before-after-control-impact estimator is adequately powered only at the upper end of feasible cluster counts and that the minimum detectable effect falls steeply as clusters increase from 8 to 32. The contribution is a design specification and a power benchmark that together define the evidence a task-shifting evaluation must generate before method-continuation claims can be treated as established.