{ "background": "Community health centres are a cornerstone of primary healthcare delivery in sub-Saharan Africa, yet systematic evidence on the factors influencing their adoption and integration into local health systems remains limited. Methodological rigour in evaluating such complex interventions in real-world settings is a persistent challenge.", "purpose and objectives": "This methodological case study aimed to design and implement a randomised field trial to rigorously evaluate the adoption rates of a standardised community health centre system. The primary objective was to demonstrate a robust experimental framework for measuring adoption, isolating causal effects from contextual noise.", "methodology": "We conducted a cluster-randomised controlled trial across 120 rural communities. The intervention was the phased introduction of a standardised operational system for community health centres. Adoption was measured via a composite index of 12 fidelity criteria. The primary analysis used an intention-to-treat approach with a mixed-effects linear probability model: $Adoption{ij} = \\beta0 + \\beta1 Treatment{ij} + \\gamma X{ij} + uj + \\epsilon{ij}$, where $uj$ are community-level random effects. Robust standard errors were clustered at the community level.", "findings": "The trial successfully demonstrated the feasibility of the methodological approach in a resource-constrained setting. The intervention arm showed a 22 percentage point increase in the mean adoption index compared to the control group (95% CI: 15 to 29). A key theme from implementation was the critical role of local health worker champions in facilitating procedural adherence.", "conclusion": "The randomised field trial proved a viable and powerful methodological design for generating causal evidence on the adoption of complex health system interventions in an African context, moving beyond observational assessments.", "recommendations": "Future evaluations of health system integration should employ randomised designs where ethically and practically feasible. Programme implementers should allocate resources for embedded methodological research to strengthen evidence-based scaling.", "key words": "randomised controlled trial, implementation science, health systems research, adoption fidelity, primary healthcare, sub-Saharan Africa