Does access to quality accreditation improve health? - Patient-level evidence from German cancer care.

Despite medical advancements, the burden of cancer is increasing. Germany introduced the accreditation of local provider networks as organ cancer centers to enhance care quality. Treatment in these centers is associated with higher survival rates, prompting policymakers to advocate for further centralization. While an impact beyond treatment outcomes has been suggested, accreditation's broader effects on population health and potential spillovers across regions remain unclear. This retrospective cohort study evaluates the impact of local access to accredited cancer care on survival for eight cancer types. Using data from the German cancer registry (1999-2018), covering 5.3 million cases, and accreditation records, we identified 861,508 patients with local access to accredited care. Using nearest neighbor matching, incorporating individual and regional factors (e.g., accreditation in neighboring districts), these patients were matched with those who lacked accredited care in their vicinity. Cox proportional hazard models and G-Computation estimated hazard ratios (HR) and intention-to-treat effects for one-, three-, and five-year survival. Access to accredited centers significantly reduces mortality risk for breast, colon, and prostate cancer (HR: 0.87-0.96) and increases five-year survival probabilities for five cancer types (1.8-7.3 percentage points), with effects varying by disease severity. Access in neighboring districts improves survival rates for several cancer types, showing positive spillover effects beyond patients' home districts. These findings emphasize the role of accreditation in improving cancer care and suggest expanding such programs could enhance outcomes without imposing travel burdens on patients.