Sex Differences in Antipsychotic and Benzodiazepine Prescribing Patterns: A Cohort Study of Newly Admitted Nursing Home Residents with Dementia in Ontario, Canada.

backgroundIn nursing homes, residents with dementia frequently receive potentially inappropriate medications that are associated with an increased risk of adverse events. Despite known sex differences in clinical presentation and sociodemographic characteristics among persons with dementia, few studies have examined sex differences in patterns and predictors of potentially inappropriate medication use.

objectivesThe objectives of this study were to examine sex differences in the patterns of antipsychotic and benzodiazepine use in the 180 days following admission to a nursing home, estimate clinical and sociodemographic predictors of antipsychotic and benzodiazepine use in male and female residents, and explore the effects of modification by sex on the predictors of using these drug therapies.

methodsWe conducted a retrospective cohort study of 35,169 adults aged 66 years and older with dementia who were newly admitted to nursing homes in Ontario, Canada between 2011 and 2014. Health administrative databases were linked to detailed clinical assessment data collected using the Resident Assessment Instrument (RAI-MDS 2.0). Cox proportional hazards models were adjusted for clinical and sociodemographic covariates to estimate the rate of antipsychotic and benzodiazepine initiation and discontinuation in the 180 days following nursing home admission in the total sample and stratified by sex. Sex-covariate interaction terms were used to assess whether sex modified the association between covariates and the rate of drug therapy initiation or discontinuation following nursing home entry.

resultsAcross 638 nursing homes, our analytical sample included 22,847 females and 12,322 males. At admission, male residents were more likely to be prevalent antipsychotic users than female residents (33.8% vs 28.3%; p < 0.001), and female residents were more likely to be prevalent benzodiazepine users than male residents (17.2% vs 15.3%, p < 0.001). In adjusted models, female residents were less likely to initiate an antipsychotic after admission (hazard ratio [HR] 0.79, 95% confidence interval [CI] 0.73-0.86); however, no sex difference was observed in the rate of benzodiazepine initiation (HR 1.04, 95% CI 0.96-1.12). Female residents were less likely than males to discontinue antipsychotics (HR 0.89, 95% CI 0.81-0.98) and benzodiazepines (HR 0.82, 95% CI 0.75-0.89). Sex modified the association between some covariates and the rate of changes in drug use (e.g., widowed males exhibited an increased rate of antipsychotic discontinuation (p-interaction = 0.03) compared with married males), but these associations were not statistically significant among females. Sex did not modify the effect of frailty on the rates of initiation and discontinuation.

conclusionsMales and females with dementia differed in their exposure to antipsychotics and benzodiazepines at nursing home admission and their patterns of use following admission. A greater understanding of factors driving sex differences in potentially inappropriate medication use may help tailor interventions to reduce exposure in this vulnerable population.