Medical Sociology of Laboratory Turnaround Time and Same-Day Antiretroviral Initiation in Zambian Clinics: A Regression-Discontinuity Estimation of Point-of-Care Testing Rollout and Treatment Delay

Point-of-care testing promises to compress the interval between HIV diagnosis and antiretroviral initiation, but the causal claim that faster laboratory turnaround produces same-day treatment rests on a fragile inferential foundation. Because no observational data are supplied, the paper characterises the operating characteristics of the proposed design under a declared variance structure: between-cluster standard deviation of 6.0, residual standard deviation of 4.5, and an intraclass correlation of 0.64. 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 requires 54 clusters to detect a 5-percentage-point effect at 80 per cent power. Turnaround time is not merely a logistical variable but a sociological one: it structures the temporal rhythm of clinic encounters, redistributes discretion between laboratory and consultation room, and determines whether the treatment decision can be co-located with the diagnostic moment. The contribution is a design specification and a conceptual mechanism, not an empirical estimate.