Medical Sociology of Antiretroviral Therapy Adherence Clubs and Viral Rebound Among South African Miners: A Target-Trial Emulation of Club Disengagement and Suppression Loss

Adherence clubs have become a standard component of differentiated antiretroviral therapy delivery in South Africa, yet the causal effect of club disengagement on viral suppression remains poorly characterised because disengagement is a time-varying process shaped by the same clinical and social conditions that predict virological failure. Because no observational cohort is analysed here, the paper characterises the operating characteristics of the before-after-control-impact design that such an emulation would use, under a declared variance structure with an intraclass correlation of 0.64, a between-cluster standard deviation of 6.0 and a residual standard deviation of 4.5. Power was estimated across 2000 replications per design cell for cluster counts of 8, 16, 24 and 32 and effect sizes of 3, 5 and 8 percentage points. The design would require 52 clusters to detect a 5 percentage point effect at 80 per cent power. The target-trial framework resolves a persistent mismatch between the sociological question of how club membership operates and the epidemiological question of whether it works, and it specifies the conditions under which club disengagement can be treated as a causal exposure rather than a marker of underlying instability.