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Sleep apnea-related factors may predict CV events

Source/Disclosures Source: Kendzerska T. PLoS Med. 2014;doi:10.1371/journal.pmed.1001599. ADD TOPIC TO EMAIL ALERTS Receive an email when new articles are posted on . Please provide your email address to receive an email when new articles are posted on Subscribe ADDED TO EMAIL ALERTS You've successfully added to your alerts. You will receive an email when new content is published.



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Obstructive sleep apnea-related factors other than apnea-hypopnea index appear to be important predictors of future CV events.

“By focusing exclusively on [apnea-hypopnea index], clinicians and researchers may have missed opportunities to better risk-stratify patients using other [obstructive sleep apnea]-related variables,” Tetyana Kendzerska, MD, MSc, of the University of Toronto, and colleagues wrote in a recent study.

The researchers conducted a historical cohort study of all adults who underwent a first diagnostic sleep study at St. Michael’s Hospital in Toronto between September 1994 and December 2010. The study included 10,149 adults (62% men; mean age, 49.9 years). Median follow-up was 68 months.

The primary outcome, a composite of MI, stroke, congestive HF, revascularization or all-cause mortality, occurred in 11.5% of participants. Apnea-hypopnea index was associated with the primary outcome in a univariate analysis (HR=1.49; 95% CI, 1.42-1.57), but after controlling for CV risk factors, the magnitude of association was attenuated and there was no difference across obstructive sleep apnea severity groups (P>.2).

The following factors were significant predictors for the primary outcome, according to a fully adjusted model:

Time spent with oxygen saturation <90% (9 minutes vs. 0 minutes; HR=1.5; 95% CI, 1.25-1.79).

Sleep time (4.9 hours vs. 6.4 hours; HR=1.2; 95% CI, 1.12-1.27).

Awakenings (35 vs. 18; HR=1.06; 95% CI, 1.02-1.1).

Periodic leg movements (13/hour vs. 0/hour; HR=1.05; 95% CI, 1.03-1.07).

Heart rate (70 bpm vs. 56 bpm; HR=1.28; 95% CI, 1.19-1.37).

Daytime sleepiness (HR=1.13; 95% CI, 1.01-1.28).

The identification of time spent with oxygen saturation <90% as the strongest predictor of CV is consistent with other research, Kendzerska and colleagues wrote.

“Our finding that a measure of hypoxia predicts CV risk is consistent with emerging evidence in both animal models and humans that intermittent hypoxia may be a crucial mechanistic link whereby [obstructive sleep apnea] causes oxidative stress, metabolic derangement and endothelial damage,” they wrote.

Recordings of the risk factors should not be difficult to obtain, even in home-based settings, they noted.

Disclosure: The researchers report no relevant financial disclosures.