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

Successful 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.

The aim was to validate PRO-PD in a random sample of outpatients with PD.

Of 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).

The 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.

PRO-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.