Association of sleep disorder with bulbar weakness and short-term outcomes in myasthenia gravis

Sleep disorder is increasingly recognized in myasthenia gravis (MG). However, its specific link to bulbar muscle weakness and short-term outcomes is not well established. This study aimed to investigate the prevalence of subjective sleep disorder (based on Pittsburgh Sleep Quality Index [PSQI] score) in a cohort of acetylcholine receptor (AChR) antibody-positive MG patients, and to explore its associations with bulbar muscle weakness, disease severity, and its value for the short-term outcome of MG.

We conducted a prospective cohort study of 163 AChR-MG patients. Subjective sleep quality was assessed using the PSQI score. Disease severity was evaluated with MG Specific Activities of Daily Living (MG-ADL) score, the Quantitative MG (QMG) score, and Myasthenia Gravis Foundation of America (MGFA) classification. Univariate and multivariable logistic regression were used to identify independent risk factors and establish prediction model for outcome. The predictive values were evaluated by receiver operating characteristic (ROC) curves. Moreover, calibration analysis and decision curve analysis (DCA) of the model were performed.

The median PSQI score was 7.0 (5.0, 9.0) and the prevalence of sleep disorder (PSQI > 5) was 73.6 %. Patients with bulbar weakness had significantly higher PSQI scores than those without (P < 0.001). PSQI score showed significant positive correlations with MG-ADL (r = 0.319, P < 0.001),QMG (r = 0.356, P < 0.001) in MG patients. A higher baseline PSQI score was identified as an independent risk factor for poor outcome at 6 months (odds ratio: 1.642 [95 % CI: 1.340-2.014], P < 0.001), with a area under curve (AUC) of 0.797. A predictive model combining PSQI score, bulbar weakness, and female gender demonstrated good discrimination, with a AUC of 0.840, a sensitivity of 0.688, and a specificity of 0.870.

Poor sleep quality is highly prevalent in AChR-MG and was more serious in patients with bulbar weakness. PSQI score was an independent risk factor for poor short-term outcome. Routine assessment of sleep may aid in risk stratification and personalized management.