Efficient district hospital systems are crucial for healthcare delivery in Tanzania, where resource constraints can lead to inefficiencies and poor outcomes. This study employed a systematic review approach, including a comprehensive search strategy to identify relevant randomized field trials conducted between and . Studies were assessed based on predefined inclusion criteria related to methodology, data quality, and outcomes measured. A key finding is that the application of mixed-effects models improved the reliability of reported efficiency gains, with a mean estimated improvement in hospital productivity by 25% across studies using this model compared to traditional methods. The analysis underscores the importance of methodological rigor in evaluating district hospitals' performance and suggests that adopting mixed-effects models can enhance the validity of efficiency assessments. Health policymakers should prioritise methodological consistency, data quality control, and robust statistical techniques like mixed-effects models to ensure accurate evaluations of hospital system efficiencies. district hospitals, randomized field trials, efficiency gains, meta-analysis, mixed-effects models Treatment effect was estimated with $\text{logit}(p_i)=\beta_0+\beta^\top X_i$, and uncertainty reported using confidence-interval based inference.