Association between restless legs syndrome and depression in patients with chronic kidney disease

Restless legs syndrome (RLS) is reportedly associated with depression. This association may be mediated by both sleep-dependent and sleep-independent mechanisms. Here we analyze the association between RLS and depressive symptoms in patients with chronic kidney disease (CKD). We also assessed whether the relationship is independent of insomnia. In a cross-sectional study, socio-demographic parameters, laboratory data, and medical history were collected from 788 kidney transplant patients and 161 dialyzed patients. Insomnia, depression, and the presence of RLS symptoms were assessed with standard questionnaires. Patients with probable RLS had a higher prevalence of depressive symptoms than those without RLS (56% vs. 22% with vs. without RLS, respectively; P<.001). Patients presenting RLS symptoms had higher Athens Insomnia Scale (AIS) scores than patients without RLS [median AIS score (interquartile range): 7 (6) vs. 3 (4) with vs. without RLS, respectively; P<.001]. The AIS score correlated with the CES-D score (Spearman's rho=0.54, P<.001). In multivariate analysis, the presence of RLS symptoms was independently associated with depressive symptoms (OR=3.96, 95% CI 2.21-7.1, P<.001). This relationship remained significant even after including insomnia in the model (OR=2.9, CI 1.55-5.43, P<.001). The presence of RLS symptoms is associated with depression in patients with CKD. This relationship remained significant even after accounting for insomnia. Sleep-independent mechanisms may also contribute to the association between RLS and depression in patients with CKD.