Inflammatory and immune mechanisms are considered in restless legs syndrome (RLS) pathophysiology with several autoimmune diseases associated with RLS. There is a paucity of studies examining RLS prevalence in myasthenia gravis (MG), an autoimmune neuromuscular disease. This study investigated RLS prevalence and association with patient-reported measures in a large registry of participants with MG using a validated RLS diagnostic questionnaire. The Myasthenia Gravis Foundation of America MG Patient Registry is used on a semi-annual basis to survey participants with MG. Patients aged ≥18 years, living in the United States, and answering "Yes" to physician diagnosed MG were invited by email to enroll in an RLS-customized web-based survey. Collection of data included demographics, disease variables, patient-reported measures with a simple depression scale, MG 15-item Quality of Life (MG-QOL15r), MG-Activities of Daily Living (MG-ADL) instruments, and 13-item short-form Cambridge-Hopkins diagnostic questionnaire for RLS (CH-RLSq13). Multivariable logistic regression models explored the association between RLS and MG variables of interest. 630 eligible participants with MG (age: 62.8±13.2; 54.9% female; 91.6% White) completed the survey. The overall prevalence of RLS was 14.8%. The prevalence of clinically significant RLS was 8.4%. The odds of having RLS were increased with higher (worse) MG-ADL, MG-QOL15r, and depression scores. History of "Thymic tumor with thymectomy" and "CPAP therapy" were also independent predictors of RLS. RLS is common in patients with MG and is associated with worse functional status, quality of life, and depression. The thymus could play a key role in an autoimmune process associating MG with RLS.
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