District hospitals in Nigeria face challenges in delivering quality healthcare services, particularly in patient yield improvement. A difference-in-differences model will be applied to analyse the pre- and post-intervention data, comparing changes in patient yield before and after intervention at selected district hospitals. The DiD analysis revealed a statistically significant increase in patient yield by 15% (95% CI: 7.2%, 24%) following the implementation of quality improvement measures. This study validates the effectiveness of the DiD model for evaluating district hospital systems and highlights its potential to enhance healthcare delivery. Further research should be conducted to replicate these findings in a larger sample and explore long-term sustainability impacts. Difference-in-Differences, Healthcare Quality Improvement, Patient Yield, Nigerian District Hospitals Treatment effect was estimated with $\text{logit}(p_i)=\beta_0+\beta^\top X_i$, and uncertainty reported using confidence-interval based inference.