Obstructive sleep apnea the most common secondary cause of hypertension associated with resistant hypertension

ABSTRACT

Recognition and treatment of secondary causes of hypertension among patients with resistant hypertension mayhelp to control blood pressure and reduce cardiovascular risk. However, there are no studies systematically evaluatingsecondary causes of hypertension according to the Seventh Joint National Committee. Consecutive patients withresistant hypertension were investigated for known causes of hypertension irrespective of symptoms and signs, includingaortic coarctation, Cushing syndrome, obstructive sleep apnea, drugs, pheochromocytoma, primary aldosteronism, renalparenchymal disease, renovascular hypertension, and thyroid disorders. Among 125 patients (age 52 1 years, 43%males, systolic and diastolic blood pressure 176 31 and 107 19 mm Hg, respectively), obstructive sleep apnea(apnea-hypopnea index 15 events per hour) was the most common condition associated with resistant hypertension(64.0%), followed by primary aldosteronism (5.6%), renal artery stenosis (2.4%), renal parenchymal disease (1.6%),oral contraceptives (1.6%), and thyroid disorders (0.8%). In 34.4%, no secondary cause of hypertension was identified(primary hypertension). Two concomitant secondary causes of hypertension were found in 6.4% of patients. Age 50years (odds ratio 5.2 [95% CI 1.9 –14.2]; P 0.01), neck circumference 41 cm for women and 43 cm for men (oddsratio 4.7 [95% CI 1.3–16.9]; P 0.02), and presence of snoring (odds ratio 3.7 [95% CI 1.3–11]; P 0.02) werepredictors of obstructive sleep apnea. In conclusion, obstructive sleep apnea appears to be the most common conditionassociated with resistant hypertension. Age 50 years, large neck circumference measurement, and snoring are goodpredictors of obstructive sleep apnea in this population.