HDCN Article Review/Hyperlink

Winkelman JW, Chertow GM, Lazarus JM

Restless leg syndrome in end-stage renal disease

Am J Kidney Dis (Sep) 28:372-378 1996

These investigators administered a questionairre to 222 hemodialysis patients in Boston, and compared their answers to those of 129 cardiology outpatients without renal disease. Symptoms of restless legs syndrome (RLS) and self-reporting of periodic leg movements to indicate periodic limb movement disorder (PLMD) were recorded in the questionairre; lab data, dialysis compliance and nerve conduction study (NCS) data (in 54% of patients) were recorded.

A RLS symptom score of 3 - 11 was calculated. ESRD patients reported delayed sleep onset (41.1 v. 23.4 mins), less total sleep time (6.2 vs 6.7 hrs), and the perception of a moderate or severe sleep problem (36% vs. 11%) statistically more often than cardiac patients. The RLS symptom score was correlated with perceived sleep problems, nocturnal awakening, sleep onset latency, less total sleep time and use of sleeping medications; it was not correlated with age, years on dialysis, URR, or abnormal NCS. Pruritus severity was not related to serum phosphate, calcium, PTH or dialysis intensity. Self reported early discontinuation of dialysis was correlated with RLS symptoms and with perceived sleep problems, less total sleep time and with a lower transferrin saturation.

There was 2.5 yr follow-up on the patients; an RLS symptom score of 7 or more was associated with a lower survival at 1 (0.82 vs. 0.91) and 2 years (0.62 vs 0.72) with P=0.06. The adjusted hazard ratio associated with RLS was 1.85 (CI= 1.12 to 3.07; P<0.02). Diabetes was not found to be a risk factor for mortality in this patient group.

Comment: This well studied group of patients adds to our understanding of RLS in dialysis patients. RLS in ESRD appears similar to the idiopathic entity. Compared with sleep apnea, RLS seems to be of equal or increased importance as a cause of sleep disturbance in dialysis patients. Interestingly, neuropathy assessed by NCS was not associated with RLS, nor was delivered URR. Low transferrin saturation was found to be associated with RLS, as has been noted in idiopathic RLS, perhaps related to an effect of iron on dopaminergic pathways in the CNS. A suggestive case was made that RLS may be a major cause of patients signing off of dialysis early, due to the inability to sit still, which contributes to an elevated mortality rate from underdialysis. This correlation of elevated mortality risk with RLS is indeed worrisome, although this study could not completely adjust for other potential comorbidities. (Stephen Pastan, M.D., Emory Clinic)