Assessing respiratory status in myasthenia gravis: limited value of the MG-ADL as a standalone tool compared with spirometry in a Danish cohort

BACKGROUND: Patients with generalized Myasthenia Gravis (gMG) may develop respiratory involvement, which can be life-threatening. In clinical practice, the Myasthenia Gravis Activities of Daily Living scale (MG-ADL) is often used to assess patient-reported respiratory impairment, as spirometry can be time-consuming and require specialized equipment and expertise. However, it is unclear whether the MG-ADL is a sufficient screening tool for identifying respiratory insufficiency. METHODS: In this cross-sectional study with a longitudinal subgroup, patients completed the MG-ADL, the Myasthenia Gravis Composite scale (MGC), and the Quantitative Myasthenia Gravis score (QMG). As a part of the QMG, spirometry was conducted. All patients had one evaluation, and a subgroup of patients had an additional evaluation after 3 years. RESULTS: One hundred patients were screened, and 70 were included and tested. Of these, 25 were retested 3 years later. Respiratory symptoms were reported by 30 (43%) of the 70 patients, though none reported severe symptoms. There was a poor correlation (r = - 0.24, p = .048) between the respiratory item of the MG-ADL and spirometry. Patients with respiratory insufficiency showed improvement over time, as did the MGC score. CONCLUSIONS: Our findings indicate limited agreement between patient-reported respiratory symptoms (MG-ADL) and spirometry measures, suggesting that spirometry remains essential for accurate assessment of respiratory function in gMG.