{ "background": "Community health centres are a cornerstone of primary healthcare delivery in many African nations, yet robust evidence on their cost-effectiveness remains limited. Rigorous methodological approaches for evaluating such complex, system-level interventions in real-world settings are needed to inform health policy and resource allocation.", "purpose and objectives": "This study aimed to appraise the methodological rigour and feasibility of a randomised field trial designed to measure the cost-effectiveness of a community health centre system in Rwanda. The primary objective was to evaluate the trial's design for generating unbiased estimates of incremental cost per disability-adjusted life year averted.", "methodology": "We conducted a parallel-group, cluster-randomised field trial. Twenty-four administrative sectors were randomly allocated to either an enhanced community health centre system intervention or standard care. Cost data were collected from health centre records and household surveys, while effectiveness was measured via population health surveys. Cost-effectiveness was estimated using a generalised linear mixed model: $\\log(\\text{Cost}{ij}) = \\beta0 + \\beta1 \\text{Treatment}j + \\mathbf{Z}{ij}\\boldsymbol{\\gamma} + uj + \\epsilon{ij}$, where $uj \\sim N(0, \\sigma^2_u)$ is a cluster random effect. Uncertainty was characterised using 95% confidence intervals derived from non-parametric bootstrapping.", "findings": "The trial design successfully generated comparable intervention and control groups at baseline. The enhanced system was associated with a non-significant trend towards higher effectiveness. A key methodological finding was that the incremental cost-effectiveness ratio point estimate was sensitive to the choice of cost-accounting perspective, with a 22% variation observed between the health system and societal perspectives. The bootstrapped confidence intervals for the primary outcome were wide, indicating substantial uncertainty.", "conclusion": "The randomised field trial proved to be a methodologically viable, though resource-intensive, approach for evaluating community health systems. The findings underscore the critical influence of analytical design choices, particularly the cost perspective,