Impact of continuous positive airway pressure therapy on restless legs syndrome in patients with coexistent obstructive sleep apnea: A qualitative systematic review

Abstract

Introduction

Obstructive sleep apnea (OSA) is characterized by repetitive episodes of complete or partial upper airway collapse during sleep. Restless legs syndrome (RLS) is a sleep-related movement disorder characterized by an uncomfortable urge to move the legs, especially during inactivity and evenings. Both OSA and RLS are common with significant overlap: RLS is present in up to 36% of those with OSA. Treatment of OSA with continuous positive airway pressure (CPAP) therapy may influence RLS outcomes. We performed a systematic review to evaluate the impact of CPAP therapy on RLS symptoms and RLS medication usage in individuals with both OSA and RLS.

Method

A comprehensive literature search was conducted in MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials, and Cochrane Database of Systematic Reviews from inception to December 7, 2024. The outcomes of interest were the improvement in RLS symptom severity, as measured by standardized scales such as the International RLS Study Group RLS Severity Scale (IRLS), and changes in the usage of RLS medications. The review included clinical trials and observational studies. Inclusion criteria were: studies with a control group or comparison period before CPAP usage, adult participants diagnosed with OSA and RLS, measurements of RLS severity using standardized scales such as the IRLS, and reports on medication usage before and after CPAP therapy. Data extraction included study characteristics, participant demographics, exposure and outcome measurements, and adjusted effect estimates. Exclusion criteria included non-primary research articles such as reviews, editorials, commentaries, letters, studies without standardized assessments of RLS symptoms, and non-English articles. The quality of included studies was assessed using the Newcastle-Ottawa Quality Scale (NOS), and the risk of bias was evaluated using the ROBINS-I tool. The systematic review was registered in PROSPERO (ID: CRD42024550240).

Results

The search identified 2,046 articles, with 291 undergoing full-text review, and three studies (3 observational, 0 RCTs) meeting the inclusion criteria, which included 479 patients. CPAP therapy was associated with improvements in RLS symptoms and a reduction in medication usage among patients with coexistent RLS and OSA. The magnitude of these effects varied, with some studies reporting significant improvements while others showed probable changes. The variability in results can be attributed to differences in study designs, sample sizes, and adjustments for confounding factors. These factors highlight the need for more rigorous research to evaluate the benefits of CPAP therapy in patients with coexistent RLS and OSA.

Conclusion

CPAP therapy appears beneficial for improving RLS symptoms and reducing medication usage in patients with coexistent OSA and RLS. However, further research with standardized diagnostic and treatment criteria, larger sample sizes, and robust adjustment for confounding factors is necessary to confirm these findings and better understand the underlying mechanisms.