{ "background": "Strengthening primary healthcare systems is a critical challenge in rapidly urbanising African contexts. While community-based health insurance and performance-based financing have been studied, the specific model of formalised urban primary care networks (UPCNs) remains under-evaluated, particularly regarding hard clinical endpoints.", "purpose and objectives": "This study aimed to determine the causal effect of a structured UPCN intervention on key clinical outcomes for hypertension and type 2 diabetes management in an urban Rwandan setting.", "methodology": "We conducted a two-arm, parallel-group, cluster-randomised field trial. Twenty-four urban health centres were randomised to implement the UPCN intervention or continue standard care. The intervention involved network-based clinical protocols, shared electronic health records, and coordinated community health worker teams. The primary outcome was the proportion of patients achieving controlled blood pressure (BP<140/90 mmHg) at 12 months. Analysis used a generalised linear mixed model: $\\text{logit}(P(Y{ij}=1)) = \\beta0 + \\beta1 \\text{Treatment}j + \\gamma X{ij} + uj$, where $u_j \\sim N(0, \\sigma^2)$, accounting for clustering.", "findings": "Patients in the UPCN arm were significantly more likely to achieve controlled blood pressure (adjusted odds ratio 1.87, 95% CI 1.32 to 2.65). The adjusted proportion with controlled hypertension was 58.3% in the intervention group versus 42.1% in the control group. Glycaemic control also showed a statistically significant improvement.", "conclusion": "The structured urban primary care network model significantly improved clinical outcomes for chronic disease management compared to standard care, demonstrating its effectiveness as a systems-level intervention.", "recommendations": "Health policymakers should consider formalising and scaling the UPCN model in urban areas. Future implementation should integrate robust digital tracking and ensure sustainable financing for network coordination functions.", "key words