Primary care physician characteristics and potentially inappropriate medications in older adults.

Background: Potentially inappropriate medications (PIMs) are a growing public health concern. While research in North America suggests physician characteristics were associated with PIM prescription, their generalizability to other countries remains understudied. Methods: We conducted a cross-sectional study using a nationwide electronic health record database of primary care clinics in Japan. We analyzed patients aged ≥75 years who visited solo-practice physicians at least quarterly during October 2022 to September 2023. Multivariable logistic regression, adjusted for patient characteristics, was used to examine the association between physician characteristics and PIM prescriptions, defined as at least one medication listed in the Screening Tool for Older Person's Appropriate Prescriptions for Japanese for ≥28 days. Results: Among 184 097 patients treated by 1532 physicians, 70 319 (38.2%) received at least one PIM. Approximately two-thirds of PIM prescriptions were concentrated among 20% of the physicians. Younger physicians (adjusted odds ratio [aOR], 1.27; 95% CI, 1.05-1.55), physicians with lower volumes of older patients (aOR, 1.39; 95% CI, 1.19-1.61), and physicians in eastern or central Japan were more likely to prescribe PIMs. Conclusions: PIM prescriptions were common and concentrated among a subset of physicians, particularly younger and less experienced physicians. Targeted interventions among high prescribers may reduce PIM efficiently.