Cooperation of General Practitioners in Referral Networks: Impact on Health Outcomes and Costs in Chronic Care

Effective coordination and cooperation between general practitioners (GPs) and other outpatient physicians are essential for managing chronic conditions. However, evidence on how the structure of outpatient referral networks supports such coordination and cooperation, and how it relates to patient outcomes is limited. This study examined whether GPs’ structural positions within outpatient referral networks were associated with hospitalization, mortality, and health care costs in patients with chronic heart failure. Using administrative claims data from Germany, we applied social network analysis to quantify GP brokerage positions ( betweenness ), GP embeddedness ( PageRank ), and GP–cardiologist connectedness ( degree ). To address potential endogeneity, we used an instrumental-variable approach, combining hurdle models for hospitalization, Cox regression for mortality, and generalized linear models for costs. More central GP brokerage positions and greater GP embeddedness in the network were associated with lower probabilities of hospitalization (7.48 and 22.27 percentage points lower, respectively; all p < 0.0001) and lower mortality (HR = 0.7149 and HR = 0.7520; both p < 0.0001), with no association observed for length of stay. These positions were also associated with higher pharmaceutical costs but lower total, outpatient, and inpatient costs; for embeddedness, the corresponding effects were €412.32 (p = 0.0052), -€1,380.49 (p = 0.0044), -€630.62 (p < 0.0001), and -€903.78 (p = 0.0107). Greater GP–cardiologist connectedness showed a similar pattern. These findings provide empirical evidence that structurally favorable GP positions within outpatient physician networks are associated with better outcomes and lower total costs in chronic care. • Outpatient chronic care is structured through referral networks. • Social networks reveal general practitioners’ structural positioning enabling cooperation. • Favorable structural positioning of GPs lowers hospitalization and mortality risk. • Favorable structural positioning of GPs reduces total costs despite higher pharmaceutical spending. • Network measures provide actionable insights in effective chronic care management.