Community health centers in Nigeria face challenges in cost-effectiveness due to varying service delivery models. A mixed-methods approach combining qualitative interviews with quantitative data collection, including surveys and financial records analysis. The study employed a difference-in-differences (DiD) regression model to estimate the impact of intervention on service delivery outcomes. Community health centers showed an average improvement in patient follow-up rates by 15% compared to baseline, indicating enhanced engagement strategies were effective. The quasi-experimental design provided robust evidence for cost-effectiveness improvements within community health centre systems, highlighting the need for consistent quality and resource allocation policies. Implementing standardised training programmes and monitoring mechanisms could further enhance service delivery outcomes and sustainability. Treatment effect was estimated with $\text{logit}(p_i)=\beta_0+\beta^\top X_i$, and uncertainty reported using confidence-interval based inference.