SAN ANTONIO — Hypertension is associated with a significantly increased prevalence of sleep apnea in patients with chronic kidney disease, Dr. Stephen F. Derose reported at a meeting of the American Heart Association Council for High Blood Pressure Research.
The clinical implication of this finding is that comorbid hypertension in patients with chronic kidney disease of any stage might reasonably lower the threshold for screening for sleep apnea, added Dr. Derose of Kaiser Permanente Medical Center, Los Angeles. Chronic kidney disease (CKD) is a major public health problem affecting an estimated 11% of the U.S. population. There has been speculation, as yet unproven, that exposure to repeated hypoxic episodes as a result of comorbid sleep apnea accelerates damage to the kidney and increases mortality risk in CKD patients.
Dr. Derose and his colleagues set about to learn whether the presence of hypertension might be a useful factor in deciding which patients with CKD should be aggressively screened for the sleep disorder.
In this large, cross-sectional observational study, he reported on nearly 721,000 adult Southern California enrollees in the Kaiser Permanente health plan with at least two glomerular filtration rate (GFR) measurements during 2000–2004. Nearly 396,000 had a GFR greater than 90 mL/min per 1.73 m
In patients with stage 1 CKD, the prevalence of hypertension in just under 5,000 patients was 74%. The prevalence of sleep apnea was 5.3%. And 87% of those with sleep apnea were hypertensive. In those with stage 2 to stage 4 CKD, the prevalence of comorbid hypertension climbed from 55% with stage 2 disease to 94% in stage 4. The prevalence of sleep apnea was steady at about 3.3%. And in patients with sleep apnea, the prevalence of hypertension rose from 66% in stage 2 CKD to 86% in stage 3 and 100% in stage 4.
All of those with sleep apnea were diagnosed clinically and were being treated, which could have blunted the observed association between lower GFR and apnea.