Trends and Contributing Factors for Prescribing Antipsychotics in Newly Diagnosed Parkinson’s Disease Patients: A Population-Based Study

PURPOSE: Psychosis is very common in later stages of Parkinson’s disease (PD) patients, but its prevalence in newly diagnosed patients is not rare. The use of antipsychotics in PD patients is complex given their association with worsening Parkinsonian motor symptoms and increased mortality rate. This study aims to examine factors that affect the use of antipsychotics in newly diagnosed PD patients and to identify changes in prescribing over time. PATIENTS AND METHODS: The Secure Anonymized Information Linkage (SAIL) databank was used to identify a cohort of newly diagnosed PD patients aged 40 years and older in Wales. The cohort was longitudinally examined over 17 years to determine the incidence of new antipsychotic use. Logistic regression models were used to analyze the data and were adjusted for several potential confounding variables. RESULTS: A total of 9142 PD patients were identified after applying inclusion and exclusion criteria, of whom 58.6% were male. During the first year of PD diagnosis, 12% of the patients developed psychosis and were prescribed antipsychotics. Quetiapine was the most commonly prescribed (49%), followed by risperidone (10.7%). The use of antipsychotics in newly diagnosed PD patients was significantly lower in the years 2009–2016 compared to 2000–2008 (OR 0.37, 95% CI 0.32–0.43). Other significant prescribing factors included patient’s age and history of dementia. CONCLUSION: A dramatic decline in antipsychotic use was identified across years, showing adherence to warnings against use of antipsychotics for PD patients. Given that psychosis is prevalent in PD patients, the continuous assessment of the safety risks of antipsychotics is a matter of priority.