Antipsychotic drug dispensing in older adults with parkinsonism

Background — Antipsychotic drugs are commonly used to treat psychosis in patients with Parkinson disease; however, individuals with parkinsonism are at risk for serious adverse effects with antipsychotic use. The choice of antipsychotic is critical.

Objective — To examine the frequency and pattern of antipsychotic prescribing to patients with Parkinson disease and parkinsonism over time.

Methods — Individuals with parkinsonism aged 66 or older in Ontario were studied in a retrospective cohort study from 2005-2013 and followed for prevalent and/or incident antipsychotic drug dispensing.

Results — In 2005, 15% of 22,837 individuals with prevalent parkinsonism were dispensed an antipsychotic drug. By 2013, the proportion was 11% of 34,262 individuals. Primary care physicians represented the vast majority of prescribers. Of individuals receiving antipsychotics in 2013, 20% were dispensed a typical antipsychotic drug. Among individuals with incident parkinsonism, living in a nursing home, older age, male sex, a greater number of comorbidities, and a prior diagnosis of dementia were significantly associated with an increased rate of receiving an antipsychotic during follow-up. Among those who received an antipsychotic, factors associated with typical antipsychotic exposure were absence of a prior diagnosis of dementia, higher Charlson comorbidity index, more concurrent medications, more recent year of first parkinsonism diagnosis and not having seen a neurologist, psychiatrist, or geriatrician.

Conclusion — A substantial proportion of individuals with parkinsonism are exposed to antipsychotic drugs, including typical antipsychotics. Given the risks of these drugs to individuals with parkinsonism, education of prescribers, particularly primary care physicians, is needed.