Eur J Neurol. 2021 Apr 10. doi: 10.1111/ene.14863. Online ahead of print.
ABSTRACT
BACKGROUND: Facioscapulohumeral muscular dystrophy is a debilitating inherited muscle disease for which various therapeutic strategies are being investigated. Thus far, little attention has been given in FSHD to the development of scientifically sound outcome measures fulfilling regulatory authorities’ requirements. The aim of this study is to design a patient-reported Rasch-built interval scale on activity and participation for FSHD.
METHODS: A pre-phase FSHD-Rasch-built overall disability scale (pre-FSHD-RODS; consisting of n=159 activity/participation items), based on the WHO international classification of disease-related functional consequences was completed by 762 FSHD patients (Netherlands: n=171; UK: n=287; USA n=221; France: n=52; Australia n=32). Part of the patients completed it twice (n=230; interval 2-4 weeks; reliability studies). The pre-FSHD-RODS was subjected to Rasch analyses to create a model fulfilling its requirements. Validity studies were performed through correlation with the Motor Function Measure.
RESULTS: The pre-FSHD-RODS did not meet the Rasch model’s expectations. Based on determinants like misfit statistics and misfit residuals, differential item functioning, and local dependency we systematically removed items until a final 38-inquiries (originating from 32 items; six items split) FSHD-RODS was constructed achieving Rasch model’s expectations. Adequate test-retest reliability and (cross-cultural and external) validity scores were obtained.
CONCLUSIONS: The FSHD-RODS is a disease-specific interval measure suitable for detecting activity and participation restrictions in patients with FSHD with good items’/persons’ reliability and validity scores. The use of this scale is recommended in the near future, determining the functional deterioration slope in FSHD per year as a preparation for the upcoming clinical intervention trials in FSHD.
PMID:33838063 | DOI:10.1111/ene.14863
