Comparison of the Quantitative Myasthenia Gravis and Myasthenia Gravis Activity of Daily Living Scores From a Clinical Practice Perspective.

Abstract

Introduction/aims: Myasthenia gravis (MG) is characterized by fluctuating symptoms, making the assessment of disease activity challenging. Discordance between the clinician-reported quantitative myasthenia gravis (QMG) score and the patient-reported MG activity of daily living (MG-ADL) has previously been observed. We aimed to compare QMG and MG-ADL in a clinical practice setting and to relate to the quality-of-life instrument myasthenia gravis quality of life 15 (MG-QoL-15).

Methods: MG patients simultaneously assessed by QMG, MG-ADL, and MG-QoL-15 (n = 177) identified in the Swedish MG registry were included. The distribution of total scores for QMG and MG-ADL and per-item score discordance was investigated using the Chi-squared test and paired t-tests. Multivariate linear regression models were constructed to identify factors associated with QMG and MG-ADL.

Results: MG-ADL exhibited a lower floor effect compared to QMG (14% vs. 28%, p = 0.002) and patients reported significantly worse scores with MG-ADL than QMG, particularly in bulbar and respiratory items (for breathing item 38% MG-ADL > QMG vs. 5% MG-ADL < QMG score). Multivariate analysis revealed that new-onset status, MG-QoL-15 score, and a history of prednisolone treatment were significantly associated with QMG scores, whereas only MG-QoL-15 was significantly associated with MG-ADL. These associations were driven by symptom-associated questions in MG-QoL-15, while the emotional well-being questions were associated with neither QMG nor MG-ADL.

Discussion: We observed that MG-ADL more readily identified residual symptoms in patients with mild disease activity compared to QMG; however, with a stronger influence of quality of life, suggesting a complementarity of the two scores in clinical practice.