Changes in Polypharmacy and Potentially Inappropriate Medications in Homebound Older Adults in Japan, 2015-2019: a Nationwide Study.

BACKGROUND: With rising worldwide population aging, the number of homebound individuals with multimorbidity is increasing. Improvement in the quality of home medical care (HMC), including medications, contributes to meeting older adults' preference for "aging in place" and securing healthcare resources. OBJECTIVE: To evaluate the changes in drug prescriptions, particularly potentially inappropriate medications (PIMs), among older adults receiving HMC in recent years, during which measures addressing inappropriate polypharmacy were implemented, including the introduction of clinical practice guidelines and medical fees for deprescribing. DESIGN: A cross-sectional study. PARTICIPANTS: Using data from the national claims database in Japan, this study included older adults aged ≥ 75 years who received HMC in October 2015 (N = 499,850) and October 2019 (N = 657,051). MAIN MEASURES: Number of drugs, prevalence of polypharmacy (≥ 5 regular drugs), major drug categories/classes, and PIMs according to Japanese guidelines were analyzed. Random effects logistic regression models were used to evaluate the differences in medications between 2015 and 2019, considering the correlation within individuals who contributed to the analysis in both years. KEY RESULTS: The number of drugs remained unchanged from 2015 to 2019 (median: 6; interquartile range: 4, 9). The prevalence of polypharmacy also remained unchanged at 70.0% in both years (P = 0.93). However, the prescription of some drugs (e.g., direct oral anticoagulants, new types of hypnotics, acetaminophen, proton pump inhibitors, and ß-blockers) increased, whereas others (e.g., warfarin, vasodilators, H2 blockers, acetylcholinesterase inhibitors, and benzodiazepines) decreased. Among the frequently prescribed PIMs, benzodiazepines/Z-drugs (25.6% in 2015 to 21.1% in 2019; adjusted odds ratio: 0.52) and H2 blockers (11.2 to 7.3%; 0.45) decreased, whereas diuretics (23.8 to 23.6%; 0.90) and antipsychotics (9.7 to 10.5%; 1.11) remained unchanged. CONCLUSIONS: We observed some favorable changes but identified some continuous and new challenges. This study suggests that continued attention to medication optimization is required to achieve safe and effective HMC.