Analysis of the Relationship between Obstructive Sleep Apnea and Venothromboembolic Events
Olson EM, Burmester JK, Berg RL, Boero JA, Karanjia PN, Mazza JJ, Schmelzer JR, Yale SH.
Clinical Research Center, Marshfield Clinic Research Foundation, Marshfield, WI.
Research area: Clinical Research
Background: Obstructive Sleep Apnea (OSA) is characterized by pauses or decreases of air flow during sleep. This condition is associated with a higher risk of cardiovascular disease including stroke and myocardial infarction. Although previous studies investigated the relationship between OSA and coagulopathy, limited information is available regarding whether OSA is a risk factor for venothromboembolic events (VTE). This study examined the VTE incidence in relation to OSA severity and treatment compliance.
Methods: This study retrospectively reviewed the electronic medical records of 619 Marshfield Clinic patients with a documented history of (a) a polysomnogram indicating OSA and (b) one or more VTE, in addition to records for 100 OSA control patients with no recorded VTE. Patients were excluded if the diagnostic polysomnogram was nonexistent or prior to 2000, or VTE diagnostic dates were nonspecific. For the 292 evaluable patients who met the diagnostic criteria, diagnosis dates determined the time between the OSA diagnosis and VTEs. OSA treatment compliance was established based on provider comments. Other abstracted data included BMI, polysomnographic variables (including Apnea/Hypopnea Index, AHI), age, gender, and hypercoaguable states.
Results: The Kaplan-Meier plot showed that the median years to VTE was 5.8 for non-compliant patients (95% confidence interval: 3.3-7.4) and 7.3 years for compliant patients (95% confidence interval: 5.9-11.3). The trend for increased VTE rate among non-compliant individuals was not significant (p=0.496). After adjusting for gender, age, BMI and AHI (a measure of OSA severity) in a proportional hazards regression model, only age was highly significant (p=0.001). AHI had a slight influence (p=0.054). Lack of statistical significance may be due to a small sample size.
Conclusions: Neither OSA severity or treatment compliance statistically changes the VTE incidence. More data on confounding variables is required before showing that OSA is an independent risk factor for VTE.