What is the clinical evidence from this study?

Study design: Cross-Sectional. Population: obstructive sleep apnea syndrome (n=130). Intervention: Clinic BP > 125/83 mmHg vs. Clinic BP ≤ 125/83 mmHg. Primary outcome: Masked hypertension (RR 2.7).

May 1, 2008

Masked hypertension in obstructive sleep apnea syndrome

Key Result

A clinic blood pressure >125/83 mmHg in patients with obstructive sleep apnea syndrome was associated with a 2.7-fold relative risk of having masked hypertension.

Study Design

Type

Cross-Sectional (n=130)

Structured PICO

What is the prevalence of masked hypertension in newly diagnosed OSAS patients, and is it associated with target organ damage?

Population

130 newly diagnosed obstructive sleep apnea syndrome patients (mean age 48, 14.6% female), free of recognized cardiovascular disease.

Outcome

Prevalence of masked hypertension and differences in baroreflex sensitivity, carotid intima-media thickness, and left ventricular mass index among blood pressure groupssurrogate

Masked hypertension is highly prevalent (30%) in newly diagnosed OSAS patients and is associated with early target organ damage, suggesting ambulatory BP monitoring should be considered when clinic BP is >125/83 mmHg.

Main Result

Relative Risk: 2.7

Abstract

BACKGROUND: Ambulatory blood pressure (BP) monitoring (ABPM) detects subjects with normal clinic but high ambulatory 24-h BP, that is, masked hypertension. METHODS: One hundred and thirty newly diagnosed obstructive sleep apnea syndrome (OSAS) patients, free of recognized cardiovascular disease were included (111 men, age = 48 +/- 1 years, BMI = 27.6 +/- 0.4 kg/m, respiratory disturbance index (RDI = 42 +/- 2/h). Clinic BP, 24-h ABPM, baroreflex sensitivity (BRS), echocardiography and carotid intima-media thickness (IMT) were assessed. RESULTS: Forty-one patients (31.5%) were normotensive, 39 (30.0%) exhibited masked hypertension, four (3.1%) white-coat hypertension and 46 (35.4%) hypertension. Significant differences were found between normotensive, masked hypertensive and hypertensive patients in terms of BRS (10.5 +/- 0.8, 8.0 +/- 0.6 and 7.4 +/- 0.4 ms/mmHg, respectively, P < 0.001), carotid IMT (624 +/- 17, 650 +/- 20 and 705 +/- 23 microm, respectively, P = 0.04) and left ventricular mass index (37 +/- 1, 40 +/- 2 and 43 +/- 1 g/height2.7, respectively, P = 0.003). A clinic systolic BP more than 125 and a diastolic BP more than 83 mmHg led to a relative risk (RR) of 2.7 and a 90% positive predictive value for having masked hypertension. CONCLUSION: Masked hypertension is frequently underestimated in OSAS and is nearly always present when clinic BP is above 125/83 mmHg.

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