Key result
Community health worker task-shifting trials require ~52 clusters to detect small hypertension control gains.
Why the study?
Task-shifting to community health workers is promoted for hypertension control in low-income settings, but existing observational comparisons cannot separate program intensity from district selection or account for diagnostic retention.
Does task-shifting to community health workers improve hypertension control in Ethiopian districts when accounting for diagnostic retention?
Does task-shifting to community health workers improve hypertension control in Ethiopian districts when accounting for diagnostic retention?
This simulation study establishes a methodological framework and power benchmark (requiring 52 clusters for 80% power to detect a 5% effect) for target-trial emulations evaluating community health worker task-shifting for hypertension control while accounting for diagnostic retention bias.
Observational task-shifting data cannot separate program intensity from district selection; leaves open whether intensive community hypertension programs improve control.
Task-shifting to community health workers is widely promoted as a strategy for hypertension control in low-income settings, yet the evidence base rests largely on observational comparisons that cannot separate program intensity from the selection of districts into intensive programming. The design parameters were eight, sixteen, twenty-four and thirty-two clusters; effect sizes of three, five and eight percentage points; a between-cluster standard deviation of 6.0, a residual standard deviation of 4.5 and an intraclass correlation of 0.640; and 2000 replications per design cell. Power was estimated across these cells. Fifty-two clusters were required to detect a five-percentage-point effect at 80 per cent power. The analysis clarifies the diagnostic-retention problem that arises when hypertension control is ascertained only among patients who remain in care, and it specifies the conditions under which the before-after-control-impact estimator recovers a task-shifting effect rather than a retention artefact. The contribution is a design framework and a power benchmark for target-trial emulation of task-shifting exposures, not an estimate of program effectiveness.
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Dibaba et al. (2026) studied Hypertension. Task-shifting to community health workers was evaluated on Hypertension control. Target-trial emulation of community health worker task-shifting for hypertension control requires 52 clusters to detect a 5-percentage-point effect at 80% power (ICC 0.640).
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