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The Limb Girdle Muscular Dystrophy Health Index (LGMD-HI)
Joy A Stouffer1, Kameron Bates2, Leroy R Thacker3
1Virginia Commonwealth University School of Medicine, 1201 E Marshall St #4-100, Richmond, VA 23298, United States.
Insights
Limb Girdle Muscular Dystrophy (LGMD) burden is now measurable with the new LGMD-Health Index (LGMD-HI). This patient-reported outcome tool is reliable and valid for assessing disease impact across LGMD subtypes.
Area of Science:
- Neurology
- Musculoskeletal Diseases
- Patient-Reported Outcomes
Background:
- Limb Girdle Muscular Dystrophy (LGMD) is a significant genetic neuromuscular disorder.
- Existing measures may not fully capture the patient experience of LGMD.
- Development of disease-specific instruments is crucial for effective management.
Purpose of the Study:
- To develop and validate the LGMD-Health Index (LGMD-HI), a patient-reported outcome measure for LGMD.
- To ensure the LGMD-HI is reliable, valid, and sensitive to changes in disease burden.
- To create a tool compliant with FDA guidelines for outcome measures.
Main Methods:
- The LGMD-HI was developed using expert review, item reduction, and psychometric analyses.
- Confirmatory factor analysis, inter-rater reliability, and internal consistency were assessed.
- Test-retest reliability and known-groups validity (ambulation status) were evaluated.
Main Results:
- The final LGMD-HI comprises 15 subscales and 97 items, demonstrating high internal consistency (Cronbach alpha=0.92) and test-retest reliability (ICC=0.97).
- The instrument showed significant differences in scores based on ambulation status, confirming validity.
- No significant variation in scores was observed based on LGMD genetic subtype, sex, or employment status.
Conclusions:
- The LGMD-Health Index (LGMD-HI) is a validated, reliable, patient-reported outcome measure for LGMD.
- The LGMD-HI effectively quantifies the burden of LGMD disease.
- This tool can be used across different LGMD subtypes, aiding clinical research and patient care.
Abstract:
Limb girdle muscular dystrophy (LGMD) is a debilitating disease and the fourth most common muscular dystrophy. This study describes the development of the LGMD-Health Index (LGMD-HI). Participants were aged >18 years and recruited from three LGMD registries and GRASP-LGMD consortium. The initial instrument, comprised of 16 thematic subscales and 161 items, underwent expert review resulting in item removal as well as confirmatory factor analysis followed by inter-rater reliability and internal consistency of the subscales. Following expert review, one subscale and 59 items were eliminated. Inter-rater reliability was assessed and five items were removed due to Cohen's kappa <0.5. The final subscales had high internal consistencies with an average Cronbach alpha of 0.92. Test re-test reliability of the final instrument was high (intraclass correlation coefficient=0.97). Known groups validity testing showed a statistically significant difference in LGMD-HI scores amongst subjects based on ambulation status (28.7 vs 50.0, p < 0.0001), but not sex, employment status, or genetic subtype. The final instrument is comprised of 15 subscales and 97 items. The LGMD-HI is a disease-specific, patient-reported outcome measure designed in compliance with published FDA guidelines. This instrument is capable of measuring burden of disease with no significant variation based on LGMD subtype.
