A study on the prevalence of RLS in OSA and the consequences of co-occurrence.

Background: Restless leg syndrome (RLS) is common among patients with obstructive sleep apnoea (OSA) but the prognostic importance of this is not studied. We have called OSA and RLS coexistence as ComOSAR. Materials and Methods: A prospective observational study was done on patients referred for polysomnography (PSG) with the aims to evaluate 1) the prevalence of RLS in OSA and comparing it with RLS in non-OSA, 2) the prevalence of insomnia, psychiatric, metabolic and cognitive disorders in ComOSAR versus OSA alone, 3) chronic obstructive airway disease (COAD) in ComOSAR versus OSA alone. OSA, RLS and insomnia were diagnosed as per respective guidelines. They were evaluated for psychiatric disorders, metabolic disorders, cognitive disorders and COAD. Results: Of 326 patients enrolled, 249 were OSA and 77 were non-OSA. 61/249 OSA patients, i.e. 24.4% had comorbid RLS, i.e. ComOSAR. RLS in non-OSA patients was similar (22/77, i.e. 28.5%); P = 0.41. ComOSAR had a significantly higher prevalence of insomnia (26% versus 10.1%; P = 0.016), psychiatric disorders (73.7% versus 48.4%; P = 0.00026) and cognitive deficits (72.1% versus 54.7%, P = 0.016) compared to OSA alone. Metabolic disorders like metabolic syndrome, diabetes mellitus, hypertension and coronary artery disease were also observed in a significantly higher number of patients with ComOSAR versus OSA alone (57% versus 34%; P = 0.0015). COAD was also seen in a significantly higher number of patients with ComOSAR compared to OSA alone (49% versus 19% respectively; P = 0.00001). Conclusion: It is essential to look for RLS in patients with OSA as it leads to a significantly higher prevalence of insomnia, and cognitive, metabolic and psychiatric disorders. COAD is also more common in ComOSAR compared to OSA alone.