Functional exercise capacity evaluated by timed walk tests in myasthenia gravis

Area of Science:

• Neurology
• Rehabilitation Medicine
• Clinical Exercise Physiology

Background:

• Myasthenia gravis (MG) is a chronic autoimmune neuromuscular disease.
• Assessing functional exercise capacity is crucial for managing MG.
• The 6-minute walk test (6mWT) and 2-minute walk test (2mWT) are commonly used functional assessments.

Purpose of the Study:

• To evaluate the test-retest reliability of the 6mWT and 2mWT in patients with generalized MG.
• To assess the construct validity of the 6mWT and 2mWT against established MG outcome measures.
• To determine the utility of these walk tests in predicting MG disease severity.

Main Methods:

• Thirty-one patients with generalized MG participated.
• Administered tests included the 6mWT, 2mWT, MG-specific quality of life questionnaire (MG-QoL15T), quantitative myasthenia gravis test (QMG), and pulmonary function tests.
• Statistical analyses included intraclass correlation coefficients and Spearman correlations.

Main Results:

• Both 6mWT and 2mWT exhibited excellent test-retest reliability (ICC: 0.932 and 0.894, respectively).
• Moderate correlations were found between walk tests and pulmonary function (FVC, MIP), QMG, and MG-QoL15T scores.
• Both tests demonstrated similar, good performance in predicting disease severity (AUC ≈ 0.76].

Conclusions:

• The 6mWT and 2mWT are reliable and valid tools for evaluating functional exercise capacity in MG patients.
• These walk tests can serve as effective measures for assessing disease severity and guiding treatment in myasthenia gravis.
• The findings support the integration of 6mWT and 2mWT into routine clinical practice for MG management.