Restless legs syndrome in patients with obstructive sleep apnea: Association between apnea severity and symptoms of depression, insomnia, and daytime sleepiness.

Objective: To determine if the prevalence and severity of restless legs syndrome (RLS) varies with apnea severity and analyze differences between the sexes in terms of comorbid RLS with symptoms of depression, insomnia, and daytime sleepiness in patients with obstructive sleep apnea (OSA).

Methods: Symptoms of depression, insomnia, and daytime sleepiness were defined as Patient Health Questionnaire-9 score ≥10, Insomnia Severity Index score ≥15, and Epworth Sleepiness Scale score ≥11. Multivariate logistic and linear regression analyses were conducted.

Results: In 707 adults with OSA (85.1% males), 16.1% (n = 114) had comorbid RLS. The prevalence of RLS was markedly lower in those with moderate and severe OSA than in those with mild OSA. Similarly, the odds of RLS significantly decreased with increasing apnea-hypopnea index. After controlling for age and sex, in patients with comorbid RLS, the International RLS Study Group Rating Scale scores were negatively correlated with apnea-hypopnea index and a nadir peripheral oxygen saturation during sleep. The presence of RLS was more likely to be associated with symptoms of depression, insomnia, and daytime sleepiness after controlling for confounding variables, but only in men.

Conclusions: RLS is frequently noted in combination with OSA, with a female preponderance. The severities of OSA and RLS may be negatively associated. In patients with OSA, sex-related differences in terms of comorbid RLS with symptoms of depression, insomnia, and daytime sleepiness warrant further investigations.