Obstructive sleep apnea is associated with interdialytic weight gain and increased long-term cardiovascular events in hemodialysis patients

Background Obstructive sleep apnea (OSA) is common in hemodialysis (HD) patients. The reasons for the high prevalence and whether OSA is associated with vascular impairment, end-organ damage, and prognosis are not completely clear. Methods We evaluated patients with low cardiovascular risk on HD, not treated by CPAP. Laboratory tests, sleep questionnaires (Berlin and Epworth) and polysonography studies, echocardiography, and markers of arterial stiffness and atherosclerosis were performed. After the initial evaluation, patients were followed up until cardiovascular events, renal transplantation, or death. Results Fifty-five patients (49% male, 50 ± 9 years, body mass index 24.7 ± 4.5 kg/m 2 ) were included. OSA (apnea-hypopnea index ≥ 5 events/h) occurred in 73% of the patients. The proportion of patients with interdialytic weight gain > 2 kg was higher in patients with OSA than those without OSA (96 vs. 55%; p = 0.002). Left ventricular (LV) posterior wall thickness (10.0 ± 1.9 vs. 11.3 ± 1.8 mm; p = 0.04) and LV diastolic diameter (48 ± 5 vs. 53 ± 5 mm; p = 0.003) were higher in patients with OSA than in patients without OSA, respectively. Sleep questionnaires did not predict OSA. No significant differences were found in pulse wave velocity, carotid intima-media thickness, and ankle-brachial index between the groups. Multivariate analysis showed that interdialytic weight gain > 2 kg and LV diastolic diameter were independently associated with OSA. On follow-up (median 45 months), OSA was found to be associated with a higher incidence of cardiovascular (CV) events (28 vs. 7%, log-rank = 0.042). Conclusions OSA was associated with increased risk of CV events. Significant (> 2 kg) interdialytic weight gain was independently associated with OSA.