Dyskinesia and Pain in Advanced Parkinson's Disease: Post Hoc Analysis from the Phase 3b, Open-Label, Randomized DYSCOVER Study

Introduction: The DYSCOVER study was a phase 3b, open-label, randomized trial (NCT02799381) that evaluated levodopa-carbidopa intestinal gel (LCIG) versus optimized medical treatment (OMT) in patients with Parkinson's disease (PD) and a high burden of dyskinesia at baseline (defined as Unified Dyskinesia Rating Scale [UDysRS] total score >= 30). At week 12, patients receiving LCIG versus OMT experienced significant improvements in dyskinesia, pain, and health-related outcomes. The objective of this analysis was to examine correlations between dyskinesia, pain, and health-related outcomes in PD. Methods: This post hoc analysis assessed correlations between UDysRS, King's Parkinson's Disease Pain Scale (KPPS), 8-item Parkinson's Disease Questionnaire (PDQ-8), Unified Parkinson's Disease Rating Scale part II, Clinical Global Impression of Severity (CGI-S) or Change (CGI-C), and "On" time without troublesome dyskinesia at baseline and after 12 weeks of LCIG or OMT. Correlations were assessed by Pearson correlation coefficients (categorization: weak, r = 0.20-0.39; moderate, r = 0.40-0.59; strong, r >= 0.60). Results: Among 61 patients, moderate-to-strong positive and significant correlations were observed between UDysRS and KPPS scores (baseline, r = 0.47; week 12 change from baseline [CFB], r = 0.63; all p < 0.001). UDysRS and KPPS scores had moderate-to-strong positive and highly significant correlations with PDQ-8 scores (baseline, r = 0.45 and 0.46, respectively; CFB, r = 0.54 and 0.64, respectively; all p < 0.001). Moderate positive and significant correlations were observed between UDysRS and CGI-S/CGI-C scores (baseline, r = 0.41; CFB, r = 0.47; all p < 0.001). Conclusions: In patients with high dyskinesia burden, positive correlations were observed between dyskinesia, pain, and health-related quality of life (HRQoL) at baseline. Improvements in dyskinesia and pain were associated with improvements in HRQoL, demonstrating the clinical burden of troublesome dyskinesia.