Polypharmacy of medications and fall-related fractures in older people in Japan: a comparison between driving-prohibited and driving-cautioned medications.

ABSTRACT

WHAT IS KNOWN AND OBJECTIVE: Polypharmacy is a risk factor for fall-related fractures. However, it is unclear whether polypharmacy itself is a direct risk factor. The aim of this study was to assess the association between the risk of fall-related fractures and polypharmacy of driving-prohibited and driving-cautioned medications in older outpatients. METHODS: We conducted a cross-sectional study of outpatients aged ≥65 years receiving any medication, using two sampling data sets from the October 2011 and October 2012 national insurance claims in Japan. Using logistic regression models, we analysed the association between the numbers of driving-prohibited or driving-cautioned medications administered or dispensed to patients and the occurrence of fall-related fractures. RESULTS AND DISCUSSION: In both analysis populations (n = 303 311 and n = 326 219), the adjusted odds ratio of driving-prohibited medications for the occurrence of fall-related fractures significantly increased as the number of these medications per patient increased (95% confidence interval 0, 1-2, 3-4, 5-6, 7-8 and ≥9 medications; reference, 0·95-1·24, 1·18-1·79, 1·47-2·96, 1·26-5·21 and 1·50-15·2 in October 2011 and reference, 1·11-1·42, 1·39-2·03, 1·33-2·72, 1·53-5·49 and 1·30-13·0 in October 2012). The association was maintained even for sensitivity analyses restricted to medications administered orally or orally and by injection. However, a similar association was not observed for driving-cautioned medications. WHAT IS NEW AND CONCLUSION: Medication class is a more important risk factor for fall-related fractures rather than polypharmacy alone with no regard to medication class.