Validation of a Parkinson's disease questionnaire-39-based functional mobility composite score (FMCS) in people with Parkinson's disease

Anne Marie Hanff*, Christopher McCrum, Armin Rauschenberger, Gloria A. Aguayo, Maurice P. Zeegers, Anja K. Leist, Rejko Krüger, NCER-PD

*Corresponding author for this work

Research output: Contribution to journalArticleResearchpeer-review


Introduction: Functional mobility is an important outcome for people with Parkinson's disease (PwP). Despite this, there is no established patient-reported outcome measure that serves as a gold standard for assessing patient-reported functional mobility in PwP. We aimed to validate the algorithm calculating the Parkinson's Disease Questionnaire-39 (PDQ-39) based Functional Mobility Composite Score (FMCS). Methods: We designed a count-based algorithm to measure patient-reported functional mobility in PwP from items of the PDQ-39 subscales mobility and activities of daily living. Convergent validity of the algorithm calculating the PDQ-39-based FMCS was assessed using the objective Timed Up and Go (n = 253) and discriminative validity was assessed by comparing the FMCS with patient-reported (MDS-UPDRS II) and clinician-assessed (MDS-UPDRS III) motor symptoms as well as between disease stages (H&Y) and PIGD phenotypes (n = 736). Participants were between 22 and 92 years old, with a disease duration from 0 to 32 years and 64.9% in a H&Y 1–2 ranging from 1 to 5. Results: Spearman correlation coefficients (rs) ranging from −0.45 to −0.77 (p < 0.001) indicated convergent validity. Hence, a t-test suggested sufficient ability of the FMCS to discriminate (p < 0.001) between patient-reported and clinician-assessed motor symptoms. More specifically, FMCS was more strongly associated with patient-reported MDS-UPDRS II (rs = −0.77) than clinician-reported MDS-UPDRS III (rs = −0.45) and can discriminate between disease stages as between PIGD phenotypes (p < 0.001). Conclusion: The FMCS is a valid composite score to assess functional mobility through patient reports in PwP for studying functional mobility in studies using the PDQ-39.

Original languageEnglish
Article number105442
JournalParkinsonism and Related Disorders
Early online date17 May 2023
Publication statusPublished - Jul 2023


  • Construct validity
  • Dimensional measurement accuracy
  • Functional status
  • Neurodegenerative diseases
  • PDQ-39
  • Psychometrics
  • Self-care
  • Social participation


Dive into the research topics of 'Validation of a Parkinson's disease questionnaire-39-based functional mobility composite score (FMCS) in people with Parkinson's disease'. Together they form a unique fingerprint.

Cite this