Breaking brand: an observational study on pharmacy-hospital-patient relationships and generic drug utilisation in Japan.

Abstract

To examine how relationships between physicians, pharmacists and patients associate with generic drug (GE) utilisation in Japan's healthcare system. Observational study using longitudinal medical claims from April 2015 to March 2021. Pharmacies across Japan serving beneficiaries of the National Health Insurance Association. 69 395 pharmacies, resulting in 322 097 pharmacy-year observations. Quantity share of GEs dispensed by pharmacies. Higher hospital prescription concentration was consistently associated with increased GE usage (1.1-2.3 percentage points higher for moderate to very high concentrations compared with low). The relationship between patient prescription concentration and GE usage varied, showing a positive association (0.3-0.6 percentage points higher) overall, but negative in settings with low hospital concentration. Smaller pharmacies exhibited a stronger positive association between hospital concentration and GE usage, while larger pharmacies and those in less urbanised areas showed a stronger positive association between patient concentration and GE usage. This study reveals that pharmacy-stakeholder relationships significantly influence GE utilisation in Japan's healthcare system. Our findings demonstrate that hospital-pharmacy relationships consistently drive generic usage, while patient-pharmacy relationships show contextual effectiveness. By measuring these relationships through concentration rates, we provide evidence that stakeholder interactions may affect medication dispensing decisions. These findings suggest that policies promoting GEs may benefit from considering the specific characteristics of pharmacies and their existing relationships with hospitals and patients. These insights can inform more effective policy design for GE promotion across different healthcare contexts.