Supplementary Material for: Snoring Amplifies the Risk of Heart Failure and Mortality in Dialysis Patients

Background: Snoring, an indicator of sleep-disordered breathing (SDB), associates with all-cause and cardiovascular (CV) mortality in high-risk conditions such as chronic heart failure (HF). Because SDB and HF are exceedingly frequent in end-stage kidney disease (ESKD), we hypothesized that SDB as detected by snoring may impact upon the relationship between chronic HF and all-cause and CV mortality in these patients. Methods: We tested this hypothesis in a cohort of 827 ESKD patients, followed up for 2.3 years. Results: In this population, snoring was a strong modifier of the risk of chronic HF for all-cause and CV death. In fully adjusted Cox models, the hazard ratio (HR) associated to chronic HF for the study outcomes was highest in heavy snorers [all-cause death: HR 2.6 (95% CI 1.6-4.3, p < 0.001); CV death: HR 4.0 (95% CI 2.1-7.6, p < 0.001)], intermediate in moderate snorers [all-cause death: HR 1.6 (95% CI 1.1-2.2, p = 0.01); CV death: HR 1.8 (95% CI 1.2-2.8, p = 0.01)], and lowest and not significant in non-snorers [all-cause death: HR 0.9 (95% CI 0.6-1.6, p = NS); CV death: HR 0.8 (95% CI 0.4-1.6, p = NS)]. Conclusions: Snoring is a strong and independent effect modifier of the relationship between chronic HF and all-cause and CV mortality in ESKD. Since SDB and snoring are in part attributable to reversible pharyngeal oedema, intensified surveillance and treatment of chronic HF snorers on dialysis may translate into better clinical outcomes in this very high-risk population, an issue which remains to be tested in specifically designed clinical trials.