Effect of total exemption from medical service co-payments on potentially inappropriate medication use among elderly ambulatory patients in a single center in Japan: a retrospective cross-sectional study

OBJECTIVE: The effect of total exemption from medical service co-payments on drug prescribing practices has not been extensively evaluated. We conducted a retrospective cross-sectional study to evaluate the effect of total exemption from medical service co-payments on potentially inappropriate medication (PIM) and benzodiazepine use in elderly ambulatory patients. We defined PIM based on the Beers Criteria. RESULTS: Six hundred seventy-one consecutive patients aged 65 years or older who routinely visited internal medicine physicians were included. Their mean age was 75.7 years, and 342 (51.0%) patients were men. The proportions of patients taking any PIMs or benzodiazepines were 37.7% and 16.2%, respectively. Of all patients, 62 (9.2%) were totally exempt from medical service co-payments. The patients who were totally exempt from medical service co-payments showed a significantly increased risk of PIM (OR 2.16, 95% CI 1.28–3.66) or benzodiazepine use (OR 2.12, 95% CI 1.16–3.87) compared with patients who were not. These associations did not change after adjusting for age, gender, comorbidities and polypharmacy. These findings should be confirmed in other settings or hospitals in Japan. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s13104-018-3320-y) contains supplementary material, which is available to authorized users.