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/m2) 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.

Potential underdiagnosis of obstructive sleep apnoea in the cardiology outpatient setting.

INTRODUCTION: Consistent evidence suggests that obstructive sleep apnoea (OSA) is associated with increased cardiovascular risk. However, it is unclear whether OSA is underdiagnosed in the cardiology outpatient setting. In the present study, we prospectively evaluated the potential underdiagnosis of OSA in several subspecialties from a tertiary cardiology university hospital. METHODS: Consecutive outpatients from five subspecialties (hypertension, coronary, arrhythmia, heart failure (HF), valvular heart disease) were studied. We performed anthropometric measurements, assessed the risk of OSA using the Berlin Questionnaire and evaluated the prior diagnosis and treatment for OSA. In a subset of patients randomly selected, we performed portable sleep monitoring to objectively evaluate the presence of OSA (defined by an apnoea-hypopnoea index ≥15 events/h of sleep). RESULTS: We evaluated 500 patients (100 from each subspecialty). The mean age and body mass index (BMI) were 59±13 years and 28.2±5.3 kg/m(2), respectively. We found that 51.6% (258 patients) had a high risk for OSA (Berlin Questionnaire). However, only 13 (3.1%) of these patients had a previous diagnosis of OSA. Of those, only six patients were receiving specific OSA treatment. Fifty patients (10 from each specialty) participated in sleep studies. No differences were found in patients who underwent sleep monitoring and those who did not. We found a high frequency of OSA (66%), varying from 50% (hypertension group) to 80% (HF group). CONCLUSIONS: Despite significant scientific evidence pointing to OSA as an emerging cardiovascular risk factor, OSA is still underdiagnosed in several cardiology subspecialties.