District hospitals in Nigeria play a crucial role in healthcare delivery but face challenges related to system reliability. A DID approach was employed to compare changes over time in district hospitals' performance against control groups, accounting for potential confounders. The analysis revealed significant improvements in outpatient services with a $[\Delta Y = \beta + \gamma_T - \delta_D]$ difference-in-differences estimate of $0.56$ (95% CI: [0.32, 0.81]) after adjusting for hospital-specific and temporal variations. The DID model effectively highlighted system improvements in outpatient services, with a notable increase in service availability. Further research should explore long-term sustainability of these improvements and broader system enhancements. district hospitals, reliability, difference-in-differences (DID), healthcare systems