Restless legs syndrome and its association with poor sleep quality, mood disorders, and one year cardiovascular mortality in patients on chronic dialysis

Abstract

Introduction Restless legs syndrome (RLS) is common among uremic patients.We assessed RLS and its association with sleep quality, psychological well-being, and one year cardiovascular mortality in patients on chronic hemodialysis (HD) and peritoneal dialysis (PD). Materials and methods Patients on chronic HD and PD were consecutively included from two medical centers in Isfahan city (Iran).Diagnosis of RLS was based on the International Restless Legs Syndrome Study Group criteria, confirmed by the validated Cambridge-Hopkins questionnaire.Patients also completed the Pittsburgh Sleep Quality Index (PSQI) and the Hospital Anxiety and Depression Scale (HADS). Laboratory tests were done for iron state, kidney function, and electrolytes.Patients were followed for one year, cardiovascular mortality and new events were recorded.Univariate and multivariate analyses were performed to analyze the data. Results Ninety patients were evaluated (53 males, age = 54.2 ± 15.2 years, disease duration = 5.3 ± 4.5 years).RLS was diagnosed in 26.6% of the patients (35.1% in females vs.20.7% in males, P = 0.019).Poor sleep quality was frequent in 86.6% of the cases in each group of the HD and PD patients.RLS severity was associated with poor sleep quality (r = 0.503, P = 0.009) and depression (r = 0.380, P = 0.05).Both anxiety and depression were also associated with poor sleep quality (r = 0.463 and 0.478, respectively, P 0.001).In multivariate analysis, having RLS ( β = 1.334, P = 0.007), anxiety ( β = 0.291, P = 0.005), and depression ( β = 0.246, P = 0.020), were independently associated with poor sleep quality.No specific association between laboratory tests’ results and overall sleep quality was observed.One year new cardiovascular events (26.0% vs.12.3%, P = 0.113) and subsequent mortality (13.0% vs.7.6%, P = 0.347) were more frequent, though not statistically significant, in those with RLS than those without RLS. Conclusion Among patients on chronic dialysis, RLS and poor sleep quality are highly frequent.Mood disorders and RLS are important independent predictors of poor sleep quality.On the other hand, RLS may be associated with increased risk of cardiovascular risk and mortality in dialysis patients.Further studies with larger sample size and longer follow-ups are required for better understanding of risk factors and also cardiovascular risk of RLS and poor sleep quality in these patients. Acknowledgements Authors are thankful to Prof. Richard Allen from the Johns Hopkins University and Dr. Mohammad Saadatnia from the Isfahan University of Medical Sciences for helping us in designing the study.