Poor Sleep, Poor HF Outcomes: Routinely Test Sleep Quality?

September 15, 2014

LAS VEGAS, NV — Nighttime sleep that's routinely poor quality, as judged by a sleep-quality questionnaire filled out by patients with heart failure, was a significant predictor of cardiac events in a small study reported here at the Heart Failure Society of America (HFSA) 2014 Scientific Meeting [1].

The approximately 60% of patients in the sample who were considered "poor sleepers" by the questionnaire showed a 2.5-fold elevated adjusted risk over an average of about one year. Poor sleep quality was a stronger predictor than even NYHA functional class.

The finding, lead author Dr Kyoung Suk Lee (University of Wisconsin-Madison) told heartwire , argues for incorporating a sleep-quality assessment into the routine evaluation of patients with heart failure. It wouldn't have to be a night in the sleep laboratory; it could be a subjective assessment, she said, such as the Pittsburgh Sleep Quality Index (PSQI) questionnaire used in the current analysis.

Sleep is well known to be important to physiological and psychological health, Lee pointed out, and sleep dysfunction can impair sympathovagal tone and promote systemic inflammation, two processes with giant roles in heart-failure pathophysiology.

In the study of 206 predominantly male patients with heart failure, including 38% in NYHA class 3–4, 64% were considered to be habitually poor sleepers by scoring a total of >5 points on the PSQI assessment. Significant correlates of poor sleep included, not surprisingly, symptoms of depression and poor NYHA functional class.

In other PSQI findings:

  • About 47% of patients reported routinely getting more than seven hours of sleep nightly, but about 18% reported less than six hours per night.

  • About half reported a "habitual sleep efficiency" of at least 85%, meaning they believed they were awake for about 15% of night bedtime. About 22% reported <65% efficiency.

  • About 15% reported taking >60 minutes to fall asleep, while 35% reported a "sleep-onset latency" of >30 minutes.

  • Whereas about 70% reported no sleep medication use in the past 30 days, 20% reported using the pills at least three times per week.

But it was a global score indicating habitually poor sleep that was prognostic.

Hazard Ratio (95% CI) for Cardiac Events* for "Poor" Sleepers (PSQI Global Score >5) vs "Good" Sleepers (and by Age and NYHA Class)

End points HR (95% CI
Poor vs good sleeper 2.54 (1.16–5.56)
NYHA class 3-4 vs 1-2 1.90 (1.06–3.40)
Age 1.028 (1.002–1.055)
*Emergency-department visit or hospitalization for heart failure or other cardiac reasons or death from cardiac causes; adjusted for age, sex, race, depression score, and NYHA functional class

Dr Kyoung Suk Lee

Although sleep-disordered breathing can be a source of sleep disturbance in heart failure and can be treated, there are other common causes on which the questionnaire can shed some light, Lee observed. For example, it can discern how often a patient wakens at night to visit the bathroom to urinate. Depending on the patient's response, all that may be needed to improve sleep is a reduction in evening fluid intake or a tweak to the diuretic dosage. Or some beta-blockers and other medications can be a source of sleep disturbance—perhaps some changes to their drug regimen will help.

As a way to get patients' own observations regarding factors that may interfere with sleep, she said, the questionnaire "can be a first step in identifying who has sleep problems leading to poor sleep quality" and potentially correcting them.

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