Morning Diastolic Blood Pressure May Be Independently Associated With Severity of Obstructive Sleep Apnea in Non-Hypertensive Patients: A Cross-Sectional Study.

Study Objectives: The aim of the study is to verify a possible association between arterial blood pressure and obstructive sleep apnea (OSA) severity in a group of non-hypertensive patients.

Methods: This is a retrospective study of 1,171 consecutive patients referred to the sleep laboratory with complaints suggestive of OSA who underwent standard diagnostic polysomnography. In total, 454 patients with no History of arterial hypertension nor had received any such treatment were selected from this group.

Results: Patients with severe OSA (apnea-hypopnea index [AHI] ≥ 30 events/h) presented with higher diastolic blood pressure (DBP) in the morning than healthy subjects (AHI < 5 events/h) or those suffering from mild (15 < AHI ≥ 5 events/h) or moderate OSA (30 < AHI ≥ 15 events/h): 86.2 ± 11.3 versus 79.2 ± 8.5, 80.3 ± 10.2 and 81.4 ± 9.6 mmHg, < .01, respectively. In a linear regression model, a rise in morning DBP was predicted by AHI (ß = 0.14, < .001) and body mass index (BMI) (ß = 0.22, < .01), but not by age (ß = 0.01, = .92), male sex (ß = -0.06, = .19), or smoking (ß = 0.01, = .86). In contrast, no association existed between morning systolic blood pressure (SBP) and AHI independently of BMI, sex, age, or smoking. High blood pressure (ie, SBP ≥ 140 mmHg or DBP ≥ 90 mmHg on each of three measurements on different occasions) was predicted by age of 42 years or older, BMI of at least 29 kg/m, and severe OSA.

Conclusions: High AHI, independent of obesity, age and sex, was associated with elevated DBP in the morning. Thus, elevated morning DBP may be one of the symptoms related to OSA that warrants specific diagnostics.

Commentary: A commentary on this article appears in this issue on page 861.