Reliability and validity of the FSHD-composite outcome measure in childhood facioscapulohumeral dystrophy

The facioscapulohumeral muscular dystrophy - health index: Italian validation of a disease-specific measure of symptomatic burden

PURPOSE

The aim of this study was to adapt the Facioscapulohumeral Muscular Dystrophy - Health Index (FSHD-HI) to an Italian population affected by FSHD by translating, validating, and testing this instrument in an Italian cohort.

MATERIALS AND METHODS

Italian FSHD patients were interviewed regarding the form and content of the translated instrument. Subsequently, forty FSHD patients were recruited to test the reliability (Intraclass Correlation Coefficient, ICC for test-retest; and Cronbach's Alpha for Internal consistency), known groups (Mann-Whitney U test and Area Under the Curve, AUC) and concurrent validity (Pearson's and Spearman's Rank Correlation Coefficient) of the instrument by serially completing the FSHD-HI and an extensive set of tests measuring the neuromotor, psychological and cognitive functions, and perceived quality of life (QoL) aspects.

RESULTS

The Italian translation of the FSHD-HI and its subscales were highly relevant to patients, had a high internal consistency (Cronbach's Alpha = 0.90), optimal test-retest reliability (ICC= 0.95), and was significantly associated with motor function, respiratory function, and QoL assessments.

CONCLUSIONS

Overall, the Italian FSHD-HI is a valid and well-suited measurement of the multi-dimensional aspects of disease burden in FSHD patients.

Facioscapulohumeral muscular dystrophy Health Index: Japanese translation and validation study

PURPOSE

The Facioscapulohumeral Muscular Dystrophy Health Index (FSHD-HI) is a patient-reported outcome measure developed for patients with FSHD. This study aimed to translate the FSHD-HI into Japanese (FSHD-HI-J), evaluate cultural adaptation, and examine its psychometric properties.

MATERIALS AND METHODS

We created two forward translations, integrated them into a single Japanese version, and evaluated the back-translated version of the FSHD-HI. After finalizing the translation and cultural adaptation, we conducted a survey of 66 patients with FSHD to examine the reliability and validity of the FSHD-HI-J. For psychometric evaluations, we used Cronbach's alpha to assess internal consistency, the intraclass correlation coefficient (ICC) for test-retest reliability, and assessed validity based on the associations between FSHD-HI-J, clinical variables, and quality of life measures.

RESULTS

The FSHD-HI-J was found to be clinically relevant, indicating high internal consistency and test-retest reliability (ICC = 0.92 [95% confidence interval: 0.86-0.95] for the total score), as well as significant associations with clinical variables (D4Z4 repeats and functional impairment) and other quality of life measures (|rho| = 0.25-0.73).

CONCLUSIONS

The FSHD-HI-J is a valid and reliable patient-reported outcome measure for Japanese patients with FSHD. This validated, disease-specific patient-reported outcome is essential for future clinical practice and clinical trials.

Meeting report: The 2023 FSHD International Research Congress

Facioscapulohumeral muscular dystrophy (FSHD) is one of the most common inherited muscular dystrophies. As part of the FSHD Society's commitment to promote global communication and collaboration among researchers, the Society collaborated with FSHD Europe and convened its 30th annual International Research Congress (IRC) on June 15-16, 2023, in the city of Milan, Italy. Over 240 researchers, clinicians, patients and pharmaceutical company representatives from a wide geographical background participated to hear about the latest developments and breakthroughs in the field. The meeting was structured to provide a mix of basic and clinical research in five sessions: 1. Discovery research & genetics; 2. Outcome assessments; 3. Disease mechanisms & interventional strategies; 4. Clinical studies & trial design; and 5. Pediatric FSHD. The keynote speakers were Professor Baziel van Engelen (on the importance of incorporating the patient's voice to help refine and improve basic laboratory and clinical research) and Dr. Bénédict Chazaud (on the role of the immune system in normal muscle regeneration and in Duchenne muscular dystrophy). The FSHD IRC was preceded by the Industry Collaborative for Therapeutic Development in FSHD meeting and followed by the World FSHD Alliance network of national patient groups and advocacy organizations for FSHD summit. The Congress concluded with the announcement for the 2024 International Research Congress, which will take place on June 13-14, 2024 in Denver, Colorado, USA, and followed by the FSHD Society's flagship educational conference for the FSHD community, the Patient Connect Conference, on June 15-16, 2024.

The Facioscapulohumeral Muscular Dystrophy-Health Index: Development and evaluation of a disease-specific outcome measure

INTRODUCTION/AIMS

As promising therapeutic interventions are tested among patients with facioscapulohumeral muscular dystrophy (FSHD), there is a clear need for valid and reliable outcome tools to track disease progression and therapeutic gain in clinical trials and for clinical monitoring. Our aim was to develop and validate the Facioscapulohumeral Muscular Dystrophy-Health Index (FSHD-HI) as a multifaceted patient-reported outcome measure (PRO) designed to measure disease burden in adults with FSHD.

METHODS

Through initial interviews with 20 individuals and a national cross-sectional study with 328 individuals with FSHD, we identified the most prevalent and impactful symptoms in FSHD. The most relevant symptoms were included in the FSHD-HI. We used patient interviews, test-retest reliability evaluation, known groups validity testing, and factor analysis to evaluate and optimize the FSHD-HI.

RESULTS

The FSHD-HI contains 14 subscales that measure FSHD disease burden from the patient's perspective. Fourteen adults with FSHD participated in semistructured beta interviews and found the FSHD-HI to be clear, usable, and relevant to them. Thirty-two adults with FSHD participated in test-retest reliability assessments, which demonstrated the high reliability of the FSHD-HI total score (intraclass correlation coefficient = 0.924). The final FSHD-HI and its subscales also demonstrated a high internal consistency (Cronbach α = 0.988).

DISCUSSION

The FSHD-HI provides researchers and clinicians with a reliable and valid mechanism to measure multifaceted disease burden in patients with FSHD. The FSHD-HI may facilitate quantification of therapeutic effectiveness, as demonstrated by its use as a secondary and exploratory measure in several clinical trials.

Correlation between whole body muscle MRI and functional measures in paediatric patients with facioscapulohumeral muscular dystrophy

Symptoms and severity of facioscapulohumeral muscular dystrophy (FSHD) can vary greatly, even within the same family. Clinical trial readiness requires accurate and reliable methods of assessing disease stage and progression. MRI has not previously been assessed as a disease biomarker in paediatric FSHD. Eleven patients with FSHD1 underwent whole body muscle MRI. Pre-selected muscles were analysed by a paediatric radiologist using the semi-quantitative Mercuri/Kim method. Within each domain (oedema, fat replacement, atrophy) scores for each muscle were then summated to give each participant three cumulative domain scores. The same participants had functional measures scored: FSHD-CSS (Ricci), FSHD-CS (Lamperti), FSHD-COM, PUL2.0, MFM-32, 6MWT, myometry and manual muscle testing. Pearson coefficient was calculated to determine strength of correlation. The scores for atrophy and fat replacement showed strong correlation with functional outcome measures, particularly FSHD-CSS, FSHD-CS and FSHD-COM. In contrast, muscle oedema correlated poorly with all functional outcome measures, with no relationship seen to the 6MWT. This study of eleven children suggests that semi-quantitative visual Mercuri score utilising fat replacement or atrophy on whole body muscle MRI correlates strongly with disease-specific functional measures and may be a useful measure of disease severity in paediatric FSHD.

Outcome Measures in Facioscapulohumeral Muscular Dystrophy Clinical Trials

Facioscapulohumeral muscular dystrophy (FSHD) is a debilitating muscular dystrophy with a variable age of onset, severity, and progression. While there is still no cure for this disease, progress towards FSHD therapies has accelerated since the underlying mechanism of epigenetic derepression of the double homeobox 4 (DUX4) gene leading to skeletal muscle toxicity was identified. This has facilitated the rapid development of novel therapies to target DUX4 expression and downstream dysregulation that cause muscle degeneration. These discoveries and pre-clinical translational studies have opened new avenues for therapies that await evaluation in clinical trials. As the field anticipates more FSHD trials, the need has grown for more reliable and quantifiable outcome measures of muscle function, both for early phase and phase II and III trials. Advanced tools that facilitate longitudinal clinical assessment will greatly improve the potential of trials to identify therapeutics that successfully ameliorate disease progression or permit muscle functional recovery. Here, we discuss current and emerging FSHD outcome measures and the challenges that investigators may experience in applying such measures to FSHD clinical trial design and implementation.