## Evidence Base Seung-No Hong, M.D., of the Korean University College of Medicine in Ansan, and colleagues conducted a study involving 146 patients with apnea. The participants were divided according to the severity of apnea into control (41 patients), mild (32 patients), moderate (30 patients), and severe (43 patients) groups. The study lasted for 6 years. Patients underwent complete nocturnal polysomnography and coagulation functional tests. Researchers were particularly interested in the relationship between apnea severity and coagulation test results, including [platelet count](https://ul.orna.me/KOge/librarybiomarker?id=83) (PLT); [bleeding time](https://ul.orna.me/KOge/librarybiomarker?id=1469) (BT); [prothrombin time](https://ul.orna.me/KOge/librarybiomarker?id=226) (PT), measured in seconds and as an international normalized ratio (INR); and activated partial thromboplastin time (aPTT). The researchers found a significant correlation between apnea index and prothrombin time. "These results suggest that patients with moderate to severe apnea have elevated clotting markers compared with healthy individuals, which may contribute to cardiovascular complications," the authors write. __Sources__: JAMA Otolaryngol Head Neck Surg. 2017;143(10):996-1002. doi:10.1001/jamaoto.2017.1367