Background: Polypharmacy and its adverse drug events are a major healthcare challenge related to falls, hospitalisations and mortality. Comprehensive geriatric assessment (CGA) may contribute to polypharmacy improvement, however, there is no clear evidence so far. Methods: Using a national inpatient database in Japan from April 1, 2014 to March 31, 2018, we investigated the association between CGA and polypharmacy. We identified patients aged ≥65 years admitted for ischaemic stroke who could receive oral medications. Propensity score matching was conducted for patients with and without CGA during hospitalisation. The outcomes were polypharmacy (defined as use of five or more types of oral medications) at discharge, the number of medication types prescribed at discharge, and the difference between the numbers of medication types prescribed on admission and at discharge. Findings: A total of 162,443 patients were analysed, of whom 39,356 (24·2%) received CGA, and propensity score matching identified 39,349 pairs. Compared with non-CGA group, the CGA group had a significantly lower proportion of polypharmacy at discharge (34·3% vs. 32·9%, p < 0·001) and a smaller number of medication types prescribed at discharge (3·84 vs. 3·76, p < 0·001). Interpretation: This study shows the clear evidence that there is a positive relationship between CGA and a reduction in the number of medications in older inpatients with ischaemic stroke. Funding: The Ministry of Health, Labour and Welfare, Japan and the Ministry of Education, Culture, Sports, Science and Technology, Japan.
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