Sleep apnea and essential hypertension: a critical review of the epidemiological evidence for co-morbidity.

This paper reviews the epidemiological literature on the linkage between sleep apnea and essential hypertension. Despite the large number of case reports, general overviews and the wide acceptance of this linkage, surprisingly, only four epidemiological articles were identified. The prevalence of sleep apnea among hypertensives ranged between 26% and 47.8% (mean = 33.6%) across the studies as compared to the estimated prevalence of 0.4% to 1.4% in the general population. There seem to be no consistently replicated risk factors for apnea amongst hypertensives, although older age, relative obesity, and severity of hypertension have been suggested as possible markers for this co-morbidity. The findings require further replication with special efforts at studying: (1) unmedicated hypertensive patients; (2) patients without significant cardiac or renal complications; and (3) patients across a broad range of age, obesity, and severity of hypertension.