Medical Sociology of Community Pharmacy Refill Reminder Enrollment and Antihypertensive Persistence in Kenyan Urban Pharmacies: A Target-Trial Emulation of Reminder Exposure

Community pharmacy refill reminders are widely promoted as a low-cost lever for antihypertensive persistence in Kenyan urban settings, yet the sociological conditions under which enrollment into such programmes becomes an effective exposure remain poorly specified. Drawing on the counterfactual tradition of target-trial emulation and on sociological work on pharmaceuticalisation, trust and the therapeutic encounter, the paper specifies the causal estimand, the eligibility criteria, the treatment strategies, the assignment procedure, the time-zero definition and the analytic model that a pharmacy-based emulation would require. Because no primary observational data are analysed here, the paper is a methodological and conceptual contribution: it formalises reminder enrollment as a time-varying, trust-contingent exposure and derives the design parameters under which a before-after-control-impact estimator would recover the intended effect. A design and power analysis under a declared variance structure (between-cluster SD = 6.0, residual SD = 4.5, intraclass correlation = 0.64) indicates that 52 clusters would be required to detect a 5-percentage-point effect at 80% power, and that power rises steeply across the 8, 16, 24 and 32 cluster configurations examined. Refill reminders should be theorised as an institutional trust signal whose effect is conditional on pharmacy-client relational continuity, and it identifies the boundary conditions under which emulation estimates would and would not be interpretable.