Pharmacy patient volume and visiting Pharmacist services: variation in patient characteristics, pharmacy attributes, and medication changes

Abstract Background Population aging is driving global demand for home-based care, and visiting pharmacist services have accordingly been reported in 11 countries worldwide. This study examined how pharmacy-level patient volume relates to patient characteristics, pharmacy attributes, and medication-related profiles and trajectories among older adults initiating these services. Methods This population-based retrospective cohort study used linked medical and long-term care insurance claims from a city in Tokyo, Japan. Participants were adults aged ≥ 65 years who started using visiting pharmacist services in fiscal years 2015–2018, grouped into tertiles of pharmacy annual patient volume. We compared patient characteristics, medication profiles including potentially inappropriate medications, and pharmacy attributes across groups. We modeled medication count trajectories using linear mixed-effects models with random intercepts for pharmacies and for participants nested within pharmacies, adjusting for recent hospitalization. Results Among 2,699 participants, high-volume pharmacies served younger patients with greater clinical complexity, including higher proportion of patients with terminal cancer (21.2% vs. 6.3% in low-volume; p < 0.001), and employed more full-time pharmacists (median 9 vs. 3; p < 0.001). Of these, 2,005 participants were included in the primary longitudinal analysis. Medication counts increased before service initiation (+0.16 drugs/month) and stabilized afterward (+0.03 drugs/month), yielding a significant change in slope (−0.13; 95% confidence interval: −0.16 to −0.10). This stabilization was consistent across volume groups. Conclusions High-volume pharmacies function as hubs for medically complex patients, supported by greater full-time staffing. Medication stabilization after service initiation was observed regardless of pharmacy volume, suggesting pharmacists engage at key care-transition points. These findings provide empirical input for workforce planning and reimbursement design for visiting pharmacist services in aging societies.