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. 2023 Jul:112:105442.
doi: 10.1016/j.parkreldis.2023.105442. Epub 2023 May 17.

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

Anne-Marie Hanff  1 , Christopher McCrum  2 , Armin Rauschenberger  3 , Gloria A Aguayo  4 , Maurice P Zeegers  5 , Anja K Leist  6 , Rejko Krüger  7 ; NCER-PD
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Free article

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

Anne-Marie Hanff et al. Parkinsonism Relat Disord. 2023 Jul.
Free article

Abstract

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.

Keywords: Construct validity; Dimensional measurement accuracy; Functional status; Neurodegenerative diseases; PDQ-39; Psychometrics; Self-care; Social participation.

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Conflict of interest statement

Declaration of competing interest This work was supported by grants from the Luxembourg National Research Fund (FNR) within the National Centre of Excellence in Research on Parkinson's disease [NCERPD(FNR/NCER13/BM/11264123)]. The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The authors declare that there are no additional disclosures to report.

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