Background and objectives
Facioscapulohumeral muscular dystrophy (FHSD) 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 authority requirements. The aim of this study was 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 159 activity/participation items), based on the World Health Organization international classification of disease‐related functional consequences was completed by 762 FSHD patients (Netherlands: n = 171; UK: n = 287; United States: n = 221; France: n = 52; Australia: n = 32). A proportion of the patient cohort 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 expectations. Based on determinants such as misfit statistics and misfit residuals, differential item functioning, and local dependency, we systematically removed items until a final 38‐inquiry (originating from 32 items; six items split) FSHD‐RODS was constructed achieving Rasch model 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 item/person reliability and validity scores. The use of this scale is recommended in the near future, to determine the functional deterioration slope in FSHD per year as a preparation for the upcoming clinical intervention trials in FSHD.
Background
International consensus on IgM ± anti‐MAG ± PNP (IgM PNP) is lacking. Despite increasing interest in clinical trials, validated disease‐specific measures are needed to adequately capture limitations and changes over time. The IMAGiNe (IgM ± anti‐myelin associated glycoprotein [MAG] peripheral neuropathy) study surges as an international collaboration to create a standardized registry of patients with IgM ± anti‐MAG PNP. The consortium, which currently consists of 11 institutions from 7 countries, presents here the IMAGiNe study design and protocol.
Aims
Functional outcome measures will be constructed at the level of impairment, as well as activity and participation. We aim to describe the natural history of the cohort, the role of anti‐MAG antibodies, the presence of clinical subtypes, and potential biomarkers.
Methods
The IMAGiNe study is a prospective, observational cohort study with a 3‐year follow‐up. At each assessment, researchers collect clinical data and subjects complete a list of preselected outcome measures. Among these, the “Pre‐Rasch‐built Overall Disability Scale (Pre‐RODS)” questionnaire will be submitted to Rasch analysis to assess classic and modern clinimetric requirements.
Results
The final measures will include the IgM‐PNP‐specific RODS and Ataxia Rating Scale (IgM‐PNP‐ARS). Descriptions of the disease course, clinical heterogeneity, treatment regimes, variations in laboratory values, and antibody titers will help reach consensus on diagnosis and follow‐up strategies.
Conclusion
The constructed interval scales will be cross‐culturally valid and suitable for use in future clinical trials and daily practice. The ultimate goals are to improve functional individualized assessment, reach international consensus, and lay the foundations for successful designs in future studies.
Clinicians and researchers have increasingly recognized the importance of improving our current measurement tools. Vanmechelen et al. confirm and contribute to this trend in their paper on the development and validation of the Second Edition of the Dyskinesia Impairment Scale. 1 The authors provide a fitting step-by-step guide for carryingThis is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.
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