SAN ANTONIO — Hypertension is associated with a significantly increased prevalence of sleep apnea among 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 (CKD) of any stage—including stage 1, marked by a normal glomerular filtration rate (GFR) plus proteinuria—might reasonably lower the threshold for screening for sleep apnea, added Dr. Derose of Kaiser Permanente Medical Center, Los Angeles.
There has been speculation 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.
But since it would be a daunting task to screen everyone with CKD for sleep apnea, 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 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 GFR measurements during 2000–2004. Nearly 396,000 had a GFR greater than 90 mL/min per 1.73 m2 and no proteinuria. The prevalence of diagnosed hypertension in this group was 28%, while 2.1% had received the diagnosis of sleep apnea. Of those with sleep apnea, 51% also had hypertension.
Patients with stage 1 CKD presented a very different picture. The prevalence of hypertension in this group of 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 patients with stage 2–4 CKD, the prevalence of comorbid hypertension rose from 55% with stage 2 disease to 94% in stage 4. The prevalence of apnea remained steady at about 3.3%. 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.
Exposure to repeated hypoxic episodes as a result of comorbid sleep apnea may accelerate damage to the kidney. DR. DEROSE