Equity Effects of Diagnostic Radiology Coverage on Avoidable Care Delays in Kenya: A Target-Trial Emulation

Evaluations of diagnostic radiology coverage in Kenya often compare facilities with and without imaging equipment, but such comparisons do not answer an equity-effect question because coverage is a cluster-level intervention entangled with referral selection, health system capacity, and social position. the present analysis specifies a target-trial emulation design for estimating the effect of functional diagnostic radiology coverage on avoidable care delays across equity-defined population strata. The target trial is conceptualised as a cluster-randomised experiment at referral-facility level, assigning a coherent radiology pathway that includes functional equipment, radiographer and radiologist presence, supplies, maintenance, referral protocols, and teleradiology linkage. The article defines causal estimands for average delay effects and for differential effects across equity groups, then derives the emulation logic from Kenyan facility inventory, referral, insurance and condition-specific delay data. It examines identification conditions—exchangeability, consistency, positivity, and interference—that take distinctive forms for shared diagnostic infrastructure. No empirical estimates are produced; the contribution is a causal architecture for future studies, with explicit boundary conditions for inference and policy use.