title: Uric acid as a potential mediator of cardiovascular morbidity in obstructive sleep apnea syndrome.
abstract: OBJECTIVE
  Obstructive sleep apnea (OSA) is now considered as an independent risk factor for cardiovascular (CV) disease. Although uric acid is increasingly being implicated in CV morbidity and mortality, no study attempted to determine independent role of uric acid in CV morbidity of OSA patients. We aimed to assess the role of serum uric acid as a potential mechanism of CV morbidity in a nonselected cohort of OSA patients.
  
  
  METHODS
  This was a cohort study in which patients who had undergone a formal sleep study for diagnosis of OSA were recruited. Included patients were grouped according to apnea-hypopnea index (AHI) as mild, moderate and severe OSA. Patients with AHI<5 served as control group. Patients were interrogated as to cardiovascular morbid conditions which included prior history and an established diagnosis of coronary artery disease, cerebrovascular accident, congestive heart failure due to coronary artery disease and arrhythmias.
  
  
  RESULTS
  436 OSA patients included (72 controls, 97 with mild, 75 with moderate, and 192 with severe OSA). The severe group also had higher serum uric acid level compared with the control and other OSA groups. Linear regression showed that the Ln uric acid was positively associated with Ln AHI score. In unadjusted logistic regression, severe OSA was associated with higher odds of a cardiovascular event, OR=2.81 (1.307-6.041), p=0.0081 while the other categories of sleep apnea were not. However, severe OSA was no longer significant after adjusting for age, gender, diabetes mellitus status, hypertension status, BMI, and smoking, OR=1.882 (0.826-4.287), p=0.1322. Uric acid was significantly higher in those who had a cardiovascular event even in the mild, moderate and severe OSA groups.
  
  
  CONCLUSIONS
  Hyperuricemia is strongly associated with cardiovascular disease in OSA patients. This strong relationship persists even after controlling for well-known traditional risk factors for cardiovascular disease.
authors.affiliation: Department of Pulmonary Medicine, Istanbul Medeniyet University School of Medicine, Istanbul, Turkey. Electronic address: kanbaydr@yahoo.com.
authors.forename: Asiye
authors.initials: A
authors.lastname: Kanbay
authors.affiliation: Department of Pulmonary Medicine, Gazi Osmanpasa University School of Medicine, Tokat, Turkey.
authors.forename: Handan
authors.initials: H
authors.lastname: Inonu
authors.affiliation: Nephrology Clinic, Karaman State Hospital, Karaman, Turkey.
authors.forename: Yalcin
authors.initials: Y
authors.lastname: Solak
authors.affiliation: Department of Medicine, Kayseri Training and Research Hospital, Kayseri, Turkey.
authors.forename: Abdulsamet
authors.initials: A
authors.lastname: Erden
authors.affiliation: Department of Medicine, Kayseri Training and Research Hospital, Kayseri, Turkey.
authors.forename: Emine
authors.initials: E
authors.lastname: Uslu
authors.affiliation: Department of Neurology, Kayseri Training and Research Hospital, Kayseri, Turkey.
authors.forename: Sevgi Arik
authors.initials: SA
authors.lastname: Yuksel
authors.affiliation: Division of Rheumatology, Department of Medicine, Istanbul Medeniyet University School of Medicine, Istanbul, Turkey.
authors.forename: Mehmet Akif
authors.initials: MA
authors.lastname: Ozturk
authors.affiliation: Division of Renal Diseases and Hypertension, University of CO, Denver, USA.
authors.forename: Kim
authors.initials: K
authors.lastname: McFann
authors.affiliation: Division of Renal Diseases and Hypertension, University of CO, Denver, USA.
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Johnson
authors.affiliation: Division of Nephrology, Department of Medicine, Istanbul Medeniyet University School of Medicine, Istanbul, Turkey.
authors.forename: Mehmet
authors.initials: M
authors.lastname: Kanbay
mesh_terms: D002318:Cardiovascular Diseases / Q000453:epidemiology*; D015331:Cohort Studies; D006801:Humans; D033461:Hyperuricemia / Q000453:epidemiology*; D012307:Risk Factors; D020181:Sleep Apnea, Obstructive / Q000097:blood* / Q000453:epidemiology*; D014527:Uric Acid / Q000097:blood*
chemical_list: D014527:Uric Acid
keywords: Cardiovascular disease; Cardiovascular risk factor; Obstructive sleep apnea; Uric acid