Concordance between patient- and physician-reported Myasthenia Gravis Activities of Daily Living(MG-ADL) scores.

Abstract

Myasthenia gravis (MG) is a neuromuscular disease characterized by abnormal skeletal muscle fatiguability. The MG Activities of Daily Living (MG-ADL) scale assesses eight symptoms and is often used as primary endpoint in MG clinical trials where it is completed by neurologists. However, in observational studies, patients frequently complete the MG-ADL scale independently of their neurologist. In this study we aimed to assess the concordance between self- and physician-reported MG-ADL scores. An international observational study was conducted among adult patients with MG scheduled for a routine visit or who entered the hospital via emergency services. Consenting patients and physicians completed the MG-ADL. Concordance between assessments was calculated using Gwet's agreement coefficient (Gwet's AC) for the MG-ADL individual items and the intraclass correlation coefficient (ICC) for the MG-ADL total score. Data were collected from 137 patients (63% female; mean age, 57.7 years). Physicians assessed the patient's symptoms as slightly more severe (8.1 vs 7.5 MG-ADL total score, respectively), corresponding to a difference of 0.6 on a range from 0 to 24. The ICC for the MG-ADL total score between the patient and the physician assessment was 0.94 (95% confidence interval, 0.89 to 0.95), showing excellent concordance. Gwet's AC showed substantial to almost perfect agreement for all items, except eyelid droop, for which the agreement was moderate. Our results demonstrate that patients and neurologists have a concordant assessment of the patient's MG symptoms when using the MG-ADL scale. This evidence supports patient self-administration of the MG-ADL in clinical practice and research.