The hypercoagulable state in sleep apnea is related to comorbid hypertension

Objective Obstructive sleep apnea (OSA) is associated with increased preval ence of atherosclerotic disease. A hypercoagulable state thought to underly atherosclerosis has been described in both OSA and systemic hypertension. We wondered about the respective contribution of apnea and hypertension to a hypercoagulable state. Design Eighty-seven subjects with symptoms suggestive of OSA, mean age 47 y ears (range 32-64 years), underwent polysomnography and blood pressure (BP) screening. OSA was diagnosed when respiratory disturbance index (RDI) grea ter than or equal to 15. Subjects having systolic BID (SBP) > 140 mmHg and/ or diastolic BP (DBP) > 90 mmHg were classified as having hypertension. Thr ee hypercoagulability markers were measured: thrombin/antithrombin III comp lex (TAT), fibrin D-dimer (DD), and von Willebrand factor antigen (vWF:ag). Results Analysis of variance and multiple linear regression were performed on the following four subject groups: (1) normotensive non-apneics (n = 19) ,(2) normotensive apneics (n = 38),(3) hypertensive non-apneics (n = 11), a nd (4) hypertensive apneics; (n = 19). OSA (groups 2 and 4) had no signific ant main effect on hemostasis. Hypertensives (groups 3 and 4) had higher pl asma levels of TAT (median/inter-quartile range, 148/59-188 versus 77/53-10 8 pmol/l; P = 0.009) and of DD (376/265-721 versus 303/190-490 ng/ml; P = 0 .040) than normotensives (groups 1 and 2). Across all subjects, SBP was the only significant predictor of TAT (P = 0.001) and of DD (P= 0.004), wherea s DBP was the only significant predictor of vWF:ag (P = 0.029). These findi ngs persisted even after controlling for gender, age, body mass index, RDI, mean SaO2, and hematocrit. Conclusion Hypercoagulability in OSA is mediated by comorbid hypertension a nd might account for high cardiovascular morbidity in OSA in general.