Add unprovoked venous thromboembolic events to the list of potential consequences of severe obstructive sleep apnea.
That conclusion comes from a study showing that patients with obstructive sleep apnea (OSA) who had the longest nocturnal hypoxemia episodes had a twofold risk for venous thromboembolic events.
systems, reported Wojciech Trzepizur, MD, of Angers University Hospital, France.
Previous studies have suggested links between OSA and both cancer and cognitive decline, but this is the first study to investigate the association between OSA and the incidence of unprovoked VTE, he reported in an oral abstract session at the annual congress of the European Respiratory Society.
“We found that those who spent more than 6% of their nighttime with levels of oxygen in their blood below 90% of normal had an almost twofold risk of developing VTEs compared to patients without oxygen deprivation,” he said.
Dr. Trzepizur and colleagues conducted a retrospective study linking cohort data to an administrative health database. They identified unprovoked VTE in patients with a suspicion for OSA and no previous VTE.
They created Cox proportional hazard models to assess the association of unprovoked VTE with apnea hypopnea index (AHI) measures and nocturnal hypoxemia markers, including the time patients spent below 90% oxygen saturation (T90), oxygen desaturation index (ODI), and hypoxic burden, defined as the total area under the respiratory event-related desaturation curve.
They found that after a median follow-up of 6.3 years, 104 out of 7,355 patients had an unprovoked VTE. In an unadjusted hazard model, there were significant associations between VTE and T90, as well as with hypoxic burden, but not with either AHI or ODI.
However, in an analysis adjusted for age, gender, body mass index, alcohol intake, hypertension, depression, history of cardiovascular disease, statin use, type of sleep study, study site, and CPAP adherence, the investigators found that only T90 remained a significant independent predictor of VTE, with a hazard ratio of 1.06, P = .02.
The association between T90 and VTE strengthened as the time spent below 90% saturation increased. Patients in the highest tercile, who spent more than 6% of the time undersaturated, had an HR for VTE of 1.95 (P = .02), compared with patients with a T90 less than 1%.
There were no significant differences in VTE risk between patients who used CPAP for more than 4 hours per night and those who either used the devices for less than 4 hours or refused CPAP.
“We see that T90 seems to be a strong parameter,” said session comoderator Raphael Heinzer, MD, MPH, of Lausanne University Hospital, Switzerland.
Dr. Heinzer’s comoderator, Silke Ryan, MD, of University College Dublin, pointed out that although T90 was the main predictor of responses, Dr. Trzepizur and colleagues did not control for other pulmonary diseases.
“Obviously, there could be an influence of other hypoxic-related diseases,” she said, and recommended controlling for this in future studies.
Winfried Randerath, MD, of the Bethanien Hospital at the University of Cologne, Germany, head of the ERS specialist group on sleep disordered breathing, said that this study and others presented at the meeting “show worrying associations between obstructive sleep apnea and important diseases that affect survival and quality of life.
“While they cannot prove that OSA causes any of these health problems, people should be made aware of these links and should try to make lifestyle changes in order to reduce their risk of OSA, for instance, by maintaining a healthy weight. However, if OSA is suspected, definite diagnosis and treatment should be initiated. We look forward to further research that may help to clarify whether OSA may be causing some of the health problems seen in these studies,” said Dr. Randerath, who was not involved with the study.
The study was supported by a grant from Institut de Recherche en Santé Respiratoire des Pays de la Loire (IRSR), Beaucouzé, France. Dr. Trzepizur, Dr. Heinzer, Dr. Ryan and Dr. Randerath reported no relevant financial relationships.
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