Risk Factors for Restless Legs Syndrome in Dialysis Patients

Background: Restless legs syndrome (RLS) is a movement disorder that affects 6.6–62% of dialysis patients. The aims of this multicentre cross-sectional study were to document the frequency, prevalence and severity of RLS in patients attending 5 dialysis centres for chronic hospital haemodialysis (HHD) and to identify associated risk factors. Methods: Thediagnosis of RLS was made using the criteria of The International Restless Legs Study Group. The following data were collected: age; gender; duration of renal replacement therapy (RRT); current smoking status; urea reduction ratio; weekly erythropoietin dose; weekly intravenous iron dose; prescribed beta blocker; prescribed renin/angiotensin system inhibitors and pre-dialysis blood concentrations of haemoglobin, ferritin, total calcium (corrected for albumin), albumin, phosphate, parathyroid hormone. Associations with RLS were analysed by univariate and multivariate logistic regression. Results: Data relating to 277 of 295 patients who had been attending for regular HHD for >3 months were collected. RLS was present in 127 (45.8%). 82 (29.6%), 27 (9.7%) and 18 (6.5%) patients had mild, moderate and severe RLS, respectively. 39 patients (14.1%) were prescribed medicines aimed at reducing RLS. 30 (76.9%) of these 39 patients still had RLS. Female gender (RR 2.17; p = 0.01), increasing duration since first dialysis (RR 1.06 per year; p = 0.03) and increasing body weight(RR 1.02 per kg; p = 0.02) were independent risk factors for RLS by multivariate analysis. In contrast to previous studies, we found no association with iron status, haemoglobin, serum phosphate or smoking. Conclusions: There is a high prevalence of RLS in our population and therapeutic intervention appears to have limited efficacy. The associations with female gender, duration of RRT and body weight deserve further study.