Incidence of antipsychotic use among community dwellers with and without Parkinson's disease

Abstract

Introduction: Previous studies have assessed antipsychotic use after Parkinson's disease (PD) diagnosis, but incident antipsychotic use before PD diagnosis is unknown. The objective is to study the incidence of antipsychotic use among community-dwelling persons with and without PD 10 years before and after the PD diagnosis.

Methods: The study was based on the nationwide register-based FINPARK-study including 20,994 persons with PD (diagnosed 1996-2015) and 142,944 comparison persons who had not used antipsychotics during one-year washout before the follow-up. PD was diagnosed according to the United Kingdom's Parkinson's disease Society Brain Bank's criteria. Antipsychotic initiations in six-month time-windows was assessed.

Results: 26.9% (n = 5,654) of people with PD initiated antipsychotics in comparison to 9.7% (n = 13,887) of people without PD during the entire follow-up. The incidence rate increased in people with PD approximately four years before the PD diagnosis. The most commonly initiated antipsychotic was quetiapine (n = 3,642, 64.4%) in persons with PD and risperidone (n = 5,232, 37.7%) in comparison persons. The initiation rates were higher in persons with PD before (6.5 and 3.0/1000 person-years for persons with and without PD, respectively, incidence rate ratio 2.18, 95%CI 2.03-2.33) and after the index date (43.3 and 11.7/1000 person-years for persons with and without PD, respectively, IRR 3.70, 95%CI 3.57-3.83).

Conclusion: Persons with PD have symptoms treated with antipsychotics both before and after diagnosis. Psychotic symptoms may be challenging to recognize as prodromal symptoms since they can occur years before the motor symptoms and thus, they cannot be clinically associated with the diagnosis of PD.

Keywords: Antipsychotic drugs; Cohort studies; Incidence; Parkinson's disease.