Association of polypharmacy with fall-related fractures in older Taiwanese people: age- and gender-specific analyses

OBJECTIVE: To elucidate the associations between polypharmacy and age- and gender-specific risks of admission for fall-related fractures. DESIGN: Nested case–control study. SETTING: This analysis was randomly selected from all elderly beneficiaries in 2007–2008, and represents some 30% of the whole older insurers using Taiwan's National Health Insurance Research Database. PARTICIPANTS: We identified 5933 cases newly admitted for fall-related fractures during 2007–2008, and 29 665 random controls free from fracture. PRIMARY AND SECONDARY OUTCOME MEASURES: Polypharmacy was defined as the use of fall-related drugs of four or more categories of medications and prescribed related to fall within a 1-year period. Logistic regression models were employed to estimate the ORs and related 95% CIs. The interaction of polypharmacy with age and sex was assessed separately. RESULTS: Compared with those who consumed no category of medication, older people who consumed 1, 2, 3 and ≥4 categories of medications were all at significantly increased odds of developing fall-related fractures, with a significant dose–gradient pattern (β=0.7953; p for trend <0.0001). There were significant interactions between polypharmacy and age, but no significant interactions between polypharmacy and gender. The dose–gradient relationship between number of medications category and risk of fall-related fractures was more obvious in women than in men (β=0.1962 vs β=0.1873). Additionally, it was most evident in older people aged 75–84 years (β=0.2338). CONCLUSIONS: This population-based study in Taiwan confirms the link between polypharmacy and increased risk of fall-related fractures in older people; and highlights that elderly women and older people aged 75–84 years will be the targeted participants for further prevention from fall-related fractures caused by polypharmacy.