DIFFERENTIAL PRESCRIBING OF ANTIMUSCARINIC AGENTS IN OLDER ADULTS WITH COGNITIVE IMPAIRMENT

OBJECTIVES: To evaluate differential prescribing of newer vs. older antimuscarinics in older adults and determine if appropriate prescribing of a newer over an older antimuscarinic occurred in persons with preexisting cognitive impairment. METHODS: We performed a population-based retrospective analysis using the 5% random sample Medicare claims data linked with Part D data from 2007 to 2012. We identified new-users of older (e.g., oxybutynin) and newer (e.g., tolterodine, trospium, solife-nacin, darifenacin, fesoterodine) antimuscarinic in adults aged 65.5 years and older, and conditions potentially associated with differential utilization of newer vs. older antimuscarinics in the 6 months prior to the first prescription using ICD-9-CM diagnosis and procedure codes and medication claims. Conditions analyzed included indicators of cognitive impairment (mild cognitive impairment, dementia, or antidementia medication), comorbid conditions (denned by Elixhauser), and other conditions common in the elderly. We used multivariate logistic regression with backward selection to assess the selection of newer vs. older antimuscarinics after adjusting for comorbid conditions. RESULTS: Of the 55,405 older adults with a new prescription for an antimuscarinic, 68% received a newer antimuscarinic as initial therapy. Overall, 7,314 patients were diagnosed or treated for dementia prior to initial therapy. Older adults diagnosed or treated for dementia were more likely (OR 1.14, 95% CI 1.07-1.20) to receive a newer compared to an older antimuscarinic. When diagnosis and treatment were considered separately in the multivariate analyses, patients treated for dementia were more likely to receive a newer antimuscarinic (OR 1.23, 95% CI 1.15-1.31). However, 29% of patients previously diagnosed or treated for dementia were initiated on an older antimuscarinic. Increased age, osteoporosis, and vertigo were associated prescription of a newer antimuscarinic. CONCLUSIONS: Older adults treated with anti-dementia medication(s) were appropriately treated with a newer antimuscarinic. Our results suggest there is still a need to improve the appropriateness of antimuscarinic prescribing.