Validation of a Patient-Reported Outcome Measure in Parkinson's Disease

Area of Science:

• Neurology
• Psychometrics
• Patient-Reported Outcomes

Background:

• The Patient-Reported Outcomes in Parkinson's Disease (PRO-PD) scale is a 35-item visual analog measure for quantifying Parkinson's disease symptom severity.
• PRO-PD is designed as a patient-centered outcome for remote, longitudinal assessment of perceived change.

Purpose of the Study:

• To evaluate the psychometric properties of the PRO-PD scale.
• To assess its reliability, validity, factor structure, and minimal clinically important difference (MCID).
• To determine its relevance for nutrition- and lifestyle-focused research.

Main Methods:

• Convergent validity assessed using established instruments in a clinical dataset (n=46).
• Internal consistency, temporal stability, factor structure, and known-groups validity evaluated in a remote-monitoring cohort (n=2612).
• MCID thresholds estimated using anchor-based methods, multinomial regression, and ROC analyses in a longitudinal subsample (n=390).

Main Results:

• PRO-PD showed strong convergent validity, excellent internal consistency (Cronbach's α = 0.93-0.95), and good test-retest reliability (ICC = 0.78-0.89).
• A four-factor solution (Neurobehavioral, Autonomic, Motor, Mood/Motivation) explained 47.6% of variance, with scores increasing with disease progression.
• MCID thresholds were +53.5 for worsening and -78.5 for improvement, with greater sensitivity for detecting deterioration.

Conclusions:

• PRO-PD is a psychometrically robust outcome measure for Parkinson's disease.
• The scale can be completed remotely without trained administrators.
• PRO-PD is suitable for longitudinal monitoring and lifestyle intervention research.