Development and Validation of the 3PDQ : A Self‐Reported Questionnaire for Diagnosing Primary Pain in Parkinson's Disease

BACKGROUND: Pain is a frequent and heterogeneous non-motor symptom of Parkinson's disease (PD). Identifying its various underlying mechanisms remains challenging, while such mechanisms are likely to drive proper therapeutic management. Among the various PD-related pain subtypes, primary Parkinsonian pain (PPP) is particularly difficult to identify and differentiate from musculoskeletal pain, due to the absence of positive diagnostic criteria. OBJECTIVES: The aim is to develop and validate the "Primary Parkinsonian Pain Diagnostic Questionnaire" (3PDQ), a self-reported tool for identifying PPP in PD. METHODS: The 3PDQ was developed through literature review and expert consensus, and refined based on patient feedback. In this multicentric study, 227 PD patients with chronic pain were recruited from 11 French Parkinson's Expert Centers; 179 were analyzed after cases were excluded where two independent expert raters made discordant types of pain diagnoses. Psychometric validation followed COSMIN standards, assessing acceptability, internal consistency, reproducibility, and diagnostic accuracy versus expert diagnosis. RESULTS: PPP was diagnosed in 36.3% of patients, whereas musculoskeletal pain was the most frequent pain subtype (42.5%). The final 11-item 3PDQ showed good acceptability (96.5% computable data), satisfactory internal consistency (Kuder-Richardson = 0.71), and excellent test-retest reliability (Lin's concordance = 0.82). The questionnaire demonstrated good discrimination between PPP and musculoskeletal pain (AUC = 0.82), with sensitivity = 82%, specificity = 74%, and a negative predictive value = 82%. CONCLUSIONS: The 3PDQ is the first validated self-reported tool for diagnosing PPP in PD. It provides a reliable, clinically feasible tool to facilitate pain phenotyping and supports the development of mechanism-based treatment strategies. © 2026 International Parkinson and Movement Disorder Society.