Antipsychotic drug prescription rates among Dutch nursing homes: the influence of patient characteristics and the dementia special care unit

Objectives: To assess the differences in antipsychotic drug prescription rates in residents with dementia in dementia special care units (SCUs) of Dutch nursing homes, considering the differences in patient characteristics. Method: As part of the Waalbed-II study, the data on antipsychotic drug use in 290 patients were collected and the Global Deterioration Scale (GDS) stage, type of dementia and behaviour (Cohen-Mansfield Agitation Inventory (CMAI)) were measured in 14 SCUs in nine nursing homes. A multilevel logistic regression model was used to assess the difference in antipsychotic drug prescription rates between dementia SCUs adjusted for age, gender, GDS stage, type of dementia and CMAI factor scores. Results: Two hundred and ninety residents met the inclusion criteria. Thirty-two per cent were prescribed an antipsychotic drug. Antipsychotic drugs were more often prescribed in patients with physically aggressive and non-aggressive behaviour and in patients with mixed dementia (vascular/Alzheimer's) than in patients with other types of dementia. Antipsychotic drug prescriptions significantly differed among the dementia SCUs. The odds of antipsychotic drug use for patients in the SCU with the highest prevalence of drug use were 2.76 (95% confidence interval (CI) 1.14-6.69) times as high as for the SCU with the lowest prevalence of drug use, taking the patient characteristics into account. Conclusion: Antipsychotic drug use in nursing home residents with dementia is not only predicted by the type of dementia and patient behaviour, but it is independently associated with the dementia SCU at which the patient resides. This result indicates that antipsychotic drugs are not only prescribed for their clinical indications (agitation/aggression) but are associated with environmental factors that may reflect a specific nursing home prescribing culture