Prevalence of restless legs and association with patient-reported outcome measures in myasthenia gravis.

Study objectives: 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.

Methods: 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.

Results: 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.

Conclusions: 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.