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. 2024 Dec;31(12):e16397.
doi: 10.1111/ene.16397. Epub 2024 Aug 28.

Improving outcome measures in late onset Pompe disease: Modified Rasch-Built Pompe-Specific Activity scale

Harmke A van Kooten  1 , Mike C Horton  2 , Stephan Wenninger  3 , Haris Babačić  3   4 , Benedikt Schoser  3 , Claire Lefeuvre  5 , Najib Taouagh  5 , Pascal Laforêt  5 , Sonia Segovia  6 , Jordi Díaz-Manera  6 , Kristl G Claeys  7   8 , Tiziana Mongini  9 , Olimpia Musumeci  10 , Antonio Toscano  10 , Thomas Hundsberger  11 , Esther Brusse  1 , Pieter A van Doorn  1 , Ans T van der Ploeg  12 , Nadine A M E van der Beek  1 ; European Pompe Consortium study group on outcome measures
Collaborators, Affiliations

Improving outcome measures in late onset Pompe disease: Modified Rasch-Built Pompe-Specific Activity scale

Harmke A van Kooten et al. Eur J Neurol. 2024 Dec.

Abstract

Background and purpose: The Rasch-Built Pompe-Specific Activity (R-PAct) scale is a patient-reported outcome measure specifically designed to quantify the effects of Pompe disease on daily life activities, developed for use in Dutch- and English-speaking countries. This study aimed to validate the R-PAct for use in other countries.

Methods: Four other language versions (German, French, Italian, and Spanish) of the R-PAct were created and distributed among Pompe patients (≥16 years old) in Germany, France, Spain, Italy, and Switzerland and pooled with data of newly diagnosed patients from Australia, Belgium, Canada, the Netherlands, New Zealand, the USA, and the UK and the original validation cohort (n = 186). The psychometric properties of the scale were assessed by exploratory factor analysis and Rasch analysis.

Results: Data for 520 patients were eligible for analysis. Exploratory factor analysis suggested that the items separated into two domains: Activities of Daily Living and Mobility. Both domains independently displayed adequate Rasch model measurement properties, following the removal of one item ("Are you able to practice a sport?") from the Mobility domain, and can be added together to form a "higher order" factor as well. Differential item functioning (DIF)-by-language assessment indicated DIF for several items; however, the impact of accounting for DIF was negligible. We recalibrated the nomogram (raw score interval-level transformation) for the updated 17-item R-PAct scale. The minimal detectable change value was 13.85 for the overall R-PAct.

Conclusions: After removing one item, the modified-R-PAct scale is a valid disease-specific patient-reported outcome measure for patients with Pompe disease across multiple countries.

Keywords: Pompe disease; Rasch analysis; daily life activities; patient‐reported outcome measure.

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Conflict of interest statement

K.G.C. has received consulting fees for advisory boards and/or received speaker honoraria from Alnylam, Amicus, ArgenX, Biogen, CSL Behring, Ipsen, Janssen, Lupin, Pfizer, Roche, Sanofi‐Genzyme, and UCB. K.G.C. is Chairholder of the Emil von Behring Chair for Neuromuscular and Neurodegenerative Disorders for CSL Behring. T.H. has received consulting fees and/or travel expenses from Amicus therapeutics, Sanofi Genzyme, Bayer, and NovoCure and has received research grants from Bayer. J.D.‐M. has received payment for consultancy from Sanofi, Astellas, Amicus, and Spark and has received grants from Sanofi and Spark. A.T.v.d.P. has received funding for research and clinical trials and advisory fees from Sanofi‐Genzyme, Amicus Therapeutics, BioMarin, Ultragenyx, Sarepta, Audentes, and Spark Therapeutics, under agreements with Erasmus MC University Medical Center and the relevant industry. N.A.M.E.v.d.B. has received consulting fees for advisory boards and/or received speaker honoraria from Sanofi under agreements with Erasmus MC University Medical Center and the relevant industry. None of the other authors has any conflict of interest to disclose.

Figures

FIGURE 1
FIGURE 1
Targeting of separate domains and combined higher order factor. ADL, Activities of Daily Living.
See this image and copyright information in PMC

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