OBJECTIVES : According to the 2015 American Geriatrics Society (AGS) Beers criteria, most antipsychotics are inappropriate in Parkinson’s disease (PD) patients due to the risk of worsening Parkinsonian symptoms. This study examined the incidence and predictors of inappropriate antipsychotic use among long-term care residents with PD and comorbid depression.

METHODS : This retrospective cohort study utilized 2007-2009 Minimum Data Set (MDS) linked to Chronic Condition Warehouse (CCW) Medicare data files involving patients with PD and comorbid depression. Using a 12-month baseline and a 24-month follow-up, the study examined incidence of inappropriate atypical antipsychotics, namely asenapine, brexpiprazole, iloperidone, lurasidone, olanzapine, paliperidone, risperidone, or ziprasidone as specified in the 2015 AGS Beers criteria. Appropriate atypical antipsychotic included aripiprazole, clozapine, or quetiapine. Multivariable logistic regression was used to examine various sociodemographic and clinical factors associated with inappropriate antipsychotic use in PD based on the Andersen Behavioral Model.

RESULTS : The incidence of atypical antipsychotic use was 17.50% (13,352/76,294) among PD patients over a 2-year follow-up. The percentage of inappropriate use among atypical antipsychotic users was 36.32%. The likelihood of inappropriate antipsychotic use was higher for patients who had dementia (OR=1.22, 95% CI: 1.12-1.33) or Chronic Obstructive Pulmonary Disease ((OR=1.13, 95% CI: 1.03-1.24). However, patients who were taking levodopa (OR=0.62, 95% CI: 0.57-0.67), dopamine agonists (OR=0.90, 95% CI: 0.82-0.98), Catechol-O-methyltransferase (COMT) inhibitors (OR=0.77, 95% CI: 0.68-0.86), Monoamine Oxidase (MAO) inhibitors type B (OR=0.72, 95% CI: 0.60-0.86), or amantadine (OR=0.84, 95% CI: 0.71-0.98) were less likely to receive inappropriate antipsychotics.

CONCLUSIONS : More than one-third of PD patients used inappropriate antipsychotics among those who were treated with atypical antipsychotic medications. Various socio-demographics and clinical factors were associated with inappropriate antipsychotic use in older patients with PD. Concerted efforts are needed to reduce inappropriate atypical antipsychotic use among PD patients.