Severe OSA doubles the risk of unprovoked VTE

Patients with obstructive sleep apnoea (OSA) who had the longest nocturnal hypoxaemia episodes have a twofold risk of developing venous thromboembolic events (VTE) in a study dubbed as the first to investigate the association between OSA and the incidence of unprovoked VTE.

The association between nocturnal hypoxemia (lower than normal arterial blood oxygen level, measured either as oxygen saturation or partial pressure of oxygen) and VTE was stronger in patients who did not use continuous positive airway pressure (CPAP) devices.

“Patients who spent more than 6 percent of their nighttime with levels of oxygen in their blood below 90 percent of normal had an almost twofold risk of developing VTEs vs patients without oxygen deprivation,” said Dr Wojciech Trzepizur from Angers University Hospital in Angers, France during his presentation at ERS 2022. [Abstract OA2288]

Previous studies have yielded conflicting findings regarding the association between OSA and incident VTE. Worse, OSA’s impact on unprovoked VTE has been narrowly investigated.

In the current study, Trzepizur’s team analysed data from the Pays de la Loire Sleep Cohort that was linked to an administrative health database in France after identifying unprovoked VTE in patients with OSA but no history of VTE.

Cox proportional hazard models were used to assess the association of unprovoked VTE with apnoea hypopnoea index (AHI) measures and nocturnal hypoxaemia markers, including the time patients spent below 90 percent oxygen saturation (T90), oxygen desaturation index (ODI), and hypoxic burden, defined as the total area under the respiratory event-related desaturation curve.

T90 independently predicts VTE

After a median follow-up of 6.3 years, there were 104 patients who had an unprovoked VTE out of 7,355 patients studied. Significant associations were found between VTE and T90, as well as with hypoxic burden, but none with either AHI or ODI, in an unadjusted hazard model.

However, T90 was the only independent predictor of VTE (hazard ratio [HR], 1.06; p=0.02) after adjusting for age, gender, BMI, alcohol intake, depression, hypertension, CVD history, statin use, and CPAP adherence, among other variables.

The association between T90 and VTE heightened as the time spent below 90 percent saturation increased. Patients in the highest tertile, who spent more than 6 percent of the time undersaturated, had an HR for VTE of 1.98 (p=0.02) vs patients with a T90 of <1 percent.

There were no significant differences in VTE risk between patients who used CPAP for >4 hours per night vs those who either used the devices for <4 hours or refused CPAP.

“T90 seems to be a strong parameter,” commented session co-moderator Dr Raphael Heinzer from Lausanne University Hospital, Lausanne, Switzerland. “There could be an influence of other hypoxic-related diseases, but we didn’t control for that,” added Heinzer’s co-author Dr Silke Ryan from University College Dublin, Ireland.

While the study cannot prove causation, people should be made aware of the link between OSA and VTE and should start to adopt lifestyle changes to reduce their risk, commented Professor Winfried Randerath of the Bethanien Hospital at the University of Cologne, Germany. “If OSA is suspected, definitive diagnosis and treatment should be initiated straight away,” he added.