Association of restless legs syndrome with oxidative stress and inflammation in patients undergoing hemodialysis

Background: Restless legs syndrome (RLS) is a common comorbidity in patients undergoing hemodialysis, but clinical factors predictive of RLS risk and severity have not been identified. The aims of this multicenter cross-sectional study were to document RLS prevalence and severity in patients undergoing hemodialysis and to identify associated risk factors. Methods: One-hundred and fifty-nine stable patients on maintenance hemodialysis were enrolled (113 men, 46 women; mean age: 68 +/- 11 years; mean duration of dialysis: 54 +/- 60 months). Diagnosis of RLS was based on the criteria proposed by the International Restless Legs Syndrome Study Group (IRLSSG), and RLS severity was assessed using the IRLSSG Severity Scale. Potential factors associated with RLS and IRLSSG Severity Scale score were assessed by univariate and multivariate regression analyses. Results: RLS affected 22% of the study population. The RLS subgroup had a significantly longer duration of hemodialysis and higher cardiothoracic ratio compared to the non-RLS subgroup. The RLS subgroup also had significantly higher serum levels of high-sensitivity C-reactive protein, interleukin-6, ferritin, N-terminal pro-B-type natriuretic peptide, and 8-hydroxy-2'-deoxyguanosine (8-OHdG), and a significantly lower transferrin saturation level compared to the non-RLS subgroup, suggesting a chronic inflammatory state and associated oxidative stress in comorbid patients. Serum 8-OHdG level was an independent risk factor for high IRLSSG Severity Scale score. Conclusion: This study confirms the high prevalence of RLS among hemodialysis patients and identifies the oxidative stress marker serum 8-OHdG as a significant independent predictor of RLS severity. Further studies are needed to identify detailed risk factors and the pathophysiological role of oxidative stress in RLS. (C) 2015 Elsevier B.V. All rights reserved.