Avaliação da presença da apneia obstrutiva do sono na doença renal crônica em pacientes na fase pré-diálise

Abstract

Introduction: Cardiovascular diseases (CVD) are common in patients with chronic kidney disease (CKD). Hypertension (H) and CVD are related to obstructive sleep apnea (OSA), the latter being more frequent in hemodialysis patients. The frequency of OSA, its relation with CVD and the progression of CKD are unknown. Objective: To investigate the presence of OSA in CKD patients, and the relation with electrocardiographic alterations, blood pressure (BP), arterial stiffness and cardiovascular (CV) or renal outcomes. Methods: Longitudinal study (24 months), 74 CKD patients stages 3b and 4. Glomerular filtration rate was estimated (eGFR) by the CKD-EPI equation. Sleep study with portable Watch-PAT200®. Diagnosis of OSA: apnea-hypopnea index (AHI) ≥ 5 ≤ 15, mild; > 15 ≤ 30, moderate; > 30, severe. BP evaluated in the office and ambulatory BP monitoring (ABPM); electrocardiogram (ECG), pulse wave velocity (PWV; Complior Analyse®). Outcomes: all-cause mortality, cardiovascular events (CV) or renal event (progression to renal replacement therapy). Statistic: software STATA 12.0. Results: Mean ± SD. Age: 63 ± 9 years, 55% male; eGFR: 29 ± 8 ml / min / 1.73m2. OSA was absent in 31% of the population (WITHOUT group, n = 23) and present in 69% (WITH group, n = 51): 49% mild, 35% moderate, 16% severe. ECG showed: maximum PR (PR max) interval and maximum P wave (P max) higher in the WITH group. The P max wave and P wave dispersion correlated positively with AHI, respiratory distress index and oxygen desaturation index. Systolic BP was higher in the WITH group, in the office and in the ABPM in all periods. The WITH group presented a higher frequency of resistant, sustained and nocturnal H. PWV was higher in subjects with moderate and severe OSA. Outcomes: one death by car accident. Without outcomes (n = 60), with CV outcomes (n = 6) and with renal outcome (n = 7). All individuals with CV outcomes presented OSA, while it was only present in 43% with renal outcome. Comparing the groups without outcomes, with CV and renal outcomes, we observed higher eGFR and lower proteinuria in those without outcomes. Regarding the PR interval and the P max wave, the values were higher in the group with CV outcomes. Additionally those with CV outcomes presented a higher risk for increased PR interval even after adjusting for confounding factors. Diastolic morning BP was also higher in the group with CV outcomes. Conclusion: CKD patients stages 3b and 4 present a high frequency of OSA, but death due to CVD was not observed. However it was associated to: specific electrocardiographic alterations, increased prevalence of hypertension despite the use of a higher number of antihypertensive drugs; and increased arterial stiffness, suggesting that the association of OSA with CKD increases CV risk. Thus, OSA should be considered a modifiable risk factor in the prevention of cardiovascular events in CKD.