The INSYTE study provides an understanding of the management of Parkinson disease psychosis (PDP) in actual practice settings, including use of antipsychotic (APs) and their impact on clinical, economic, and humanistic outcomes. Treatment paradigms or the benefits/consequences of various “real world” PDP treatment strategies have not been evaluated. Thus, providers may be using a wide range of AP treatment strategies that contrast with consensus recommendations.

The INSYTE study is enrolling up to 750 patients from up to 100 sites in the US. Data are compiled at the baseline (BL) visit and from standard-of-care follow up visits over 3 years. PDP treatment pathways are defined from 3 BL cohorts reflecting (1) no AP medication, (2) use of pimavanserin (PIM), or (3) other AP treatment. Information about APs used is collected at each follow-up visit: history, duration, dose, adjustment, and rationale for adjustment of treatment. Outcomes assessments (clinical, quality of life, disease burden) by the physician, patient, and caregiver are also collected. AP medication and outcomes data are analyzed for patients completing a BL and 1 follow up visit (FU1).

For 404 patients with BL and FU1 visits (mean 120.7 days from BL), 56.8% used no AP medications, 26.0% used PIM, and 13.6% used other APs at BL. The No Medication group was noted to be less severe in key BL disease parameters. Considering primary PDP treatments at BL and FU1 (including no treatment), 26 distinct pathways were being employed. 12.6% of patients had AP medication adjustments between BL and FU1 visits, most frequently from the non-PIM group. Adjustments of APs occurred in many forms: introduction of a single AP (64.7%%), introduction of multiple APs (5.9%), switching to another AP (3.9%), decreasing the number of APs (5.9%), and discontinuation (19.6%).

Multiple, divergent AP treatment strategies for PDP exist in actual practice. No identifiable BL characteristics correlated with the broad range of AP treatment pathways. The numerous distinct AP treatment pathways utilized (n=26) reflect discordance with the updated 2019 MDS evidence-based recommendations, which recognize only 2 APs as “efficacious” and “clinically useful”: pimavanserin and clozapine. Education of healthcare professionals remains a priority for PDP management.

ACADIA Pharmaceuticals Inc.