Validation of the Swedish Patient‐Reported Outcomes in Parkinson's Disease Scale in Outpatients

Abstract

AbstractBackgroundSuccessful treatment of Parkinson's disease (PD) requires symptom monitoring. Patient‐Reported Outcomes in Parkinson's Disease (PRO‐PD) is a broad scale that covers 35 motor and nonmotor symptoms, but its validation is limited.ObjectiveThe aim was to validate PRO‐PD in a random sample of outpatients with PD.MethodsOf 2123 PD patients who visited outpatient clinics in West Sweden over a 12‐month period, 25% were randomly selected and invited to participate in a longitudinal observational study. Included patients were assessed at baseline, 1 year, and 3 years, with a subset also assessed at 3 to 6 months. The assessments included PRO‐PD, other patient‐reported scales, and Clinical Impression of Severity Index for Parkinson's Disease (CISI‐PD).ResultsThe study included 286 PD patients. PRO‐PD ratings were available from 716 (96%) of 747 study visits. All PRO‐PD items exhibited positive skewness without ceiling effects. Internal consistency at baseline was excellent (Cronbach's α: 0.93). Six‐month test–retest reliability was good (intraclass correlation coefficient: 0.87). Convergent validity was good, with correlation coefficients between total PRO‐PD and the 8‐Item Parkinson's Disease Questionnaire of 0.70, the Non‐Motor Symptoms Questionnaire of 0.70, EuroQoL Five‐Dimension Five‐Level Scale of 0.71, and CISI‐PD of 0.69. Median PRO‐PD score at baseline was 995 (interquartile range: 613–1399), with a median yearly increase of 71 (interquartile range: −21 to 111). Items representing axial motor symptoms increased most over time. The minimal clinically important change in total score was 119.ConclusionsPRO‐PD was found reliable and valid for monitoring symptoms in a representative sample of outpatients with PD. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.