{ "background": "District hospitals are critical nodes in sub-Saharan African health systems, yet systematic longitudinal evidence on the impact of operational optimisation on their yield—defined as the composite measure of clinical output per unit resource input—remains scarce. Prior evaluations have often been cross-sectional or lacked robust counterfactuals.", "purpose and objectives": "This study aimed to quantify the causal effect of a multi-component system optimisation intervention on hospital yield over time, using a quasi-experimental design to isolate the intervention's impact from secular trends.", "methodology": "We employed a longitudinal, controlled interrupted time-series analysis. A cohort of 42 hospitals was non-randomly assigned to intervention (n=21) or control (n=21) groups. The intervention comprised supply chain digitisation, staff task-shifting protocols, and modular infrastructure upgrades. Yield was modelled as a function of intervention status, time, and their interaction, controlling for baseline covariates: $Y{it} = \\beta0 + \\beta1(Interventioni) + \\beta2(Timet) + \\beta3(Interventioni \\times Timet) + \\gamma X{it} + \\epsilon{it}$. Data were collected annually. Inference was based on cluster-robust standard errors.", "findings": "Preliminary analysis of the first phase indicates a positive trajectory for the intervention group. The adjusted yield coefficient for the interaction term, $\\beta3$, was 0.18 (95% CI: 0.09, 0.27), suggesting a significant differential increase. A key theme from process data was the critical role of mid-level management engagement in mediating implementation success.", "conclusion": "The optimisation package shows promise for sustainably improving hospital system performance. The quasi-experimental design provides stronger causal evidence than previously available for such complex health system interventions.", "recommendations": "Policy should prioritise integrated optimisation packages over single-component reforms. Future implementations must invest in local management capacity to ensure fidelity and adapt