Potentially inappropriate medications increase while prevalence of polypharmacy/hyperpolypharmacy decreases in Japan: A comparison of nationwide prescribing data

Abstract

BackgroundTo elucidate recent prescription trends for older adults and the background underlying changes over time with a particular focus on the prevalence of polypharmacy and potentially inappropriate medications (PIMs). MethodsWe cross-sectionally collected prescription data of patients aged ≧65 years who visited chain pharmacies dispensing prescribed drugs from all types of outpatient settings for one month in two sampling periods (October, 2014 and December, 2019), and the data were analysed. Prevalence of polypharmacy and factors associated with PIMs between the two periods were investigated. ResultsThe average number of drugs prescribed decreased over time (4.05 ± 3.24 in 2014 vs. 3.98 ± 3.16 in 2019, p < 0.001), as did the prevalence of polypharmacy (50.1% in 2014 vs. 48.2% in 2019, p < 0.001). Meanwhile, the prevalence of PIMs exhibited a marked increase (overall: 26.8% in 2014 vs. 43.7% in 2019, aged 65-74: 25.6% in 2014 vs. 40.3% in 2019, aged 75-84: 27.4% in 2014 vs. 43.9% in 2019), which was the most pronounced in patients aged over 85 (29.4% in 2014 vs. 53.0% in 2019). The number of classes of drugs positively associated with PIMs in 2019 increased from that in 2014. The increasing trend was most prominently observed in the oldest age category (over 85 years, 2 in 2014 vs. 6 in 2019). ConclusionsThe comparison of monthly prescribing data with an interval of 5 years suggested an increasing trend in the prevalence of PIMs, contrary to the declining prevalence of polypharmacy.