Intercountry comparisons of advanced Parkinson's disease symptoms and management: Analysis from the OBSERVE-PD observational study

Objectives In the absence of widely accepted criteria, determining when a patient with Parkinson's disease (PD) may benefit from more advanced treatments such as device-aided therapy (DAT) so far remains a matter of physician judgment. This analysis investigates how classification of PD varies across countries relative to measures of disease severity. Materials and Methods The OBSERVational, cross-sEctional PD (OBSERVE-PD) study included consecutive patients with PD at centers that offer DATs in 18 countries. In this subgroup analysis, we explore intercountry differences in identification of advanced versus non-advanced PD based on physician's clinical judgment, symptoms assessed using Delphi consensus criteria, use of DAT, motor and non-motor symptoms, and caregiver support. Demographic and clinical characteristics were obtained through review of medical records. Results Overall, 1342 of 2615 patients (51.3%) were assessed by physicians as having advanced PD. The proportion of patients in different countries identified as having advanced PD (24.4-82.2%) varied. In 15 of 18 countries, a greater proportion of patients with advanced PD, according to select Delphi criteria, were identified by physicians as having advanced PD than with non-advanced PD. There was a wide variability across countries in the proportion of patients with no dyskinesia, disabling dyskinesia, dyskinesia pain, and non-motor symptoms who were identified by physicians as having advanced versus non-advanced PD. Conclusions The proportion of patients identified with advanced PD symptoms varies widely across countries, despite differences on the patients' profiles, indicating a need for objective diagnostic criteria to help identify patients who may benefit from DAT.