Obstructive sleep apnea linked with decreased exercise capacity

By Lorraine L. Janeczko

NEW YORK (Reuters Health) - Patients with untreated obstructive sleep apnea (OSA) may also have decreased exercise capacity, according to results of a new systematic review and meta-analysis.

“Since exercise capacity is impaired in obstructive sleep apnea patients, advising weight loss alone as a treatment modality is likely inadequate, since these patients may have difficulty losing weight with exercise,” lead author Dr. Gaurav Singh of the Stanford School of Medicine in Palo Alto, California, told Reuters Health by email.

“Treating the underlying sleep apnea, mainly with continuous positive airway pressure (CPAP), even for mild sleep apnea, is an essential initial step to interrupt the vicious cycle,” he said.

The findings were presented June 4 in Boston at SLEEP 2017, the joint meeting of the American Academy of Sleep Medicine and the Sleep Research Society.

Dr. Singh and colleagues searched the literature for original studies and reviews evaluating exercise capacity in OSA in any language up until April 2016. After they excluded studies involving patients treated with positive airway pressure or those with systolic heart failure, as well as studies lacking a control group, they included 45 studies comprising close to 5,400 patients in their review.

Compared with 659 controls, the pooled mean difference in VO2 among 741 participants with OSA was -3.096 ml/kg/min, using a random effects model.

The researchers also found a -16.928-watt difference in workload between the groups, but they found no differences in anaerobic threshold, O2 pulse, breathing reserve, ventilatory efficiency, or maximal ventilation.

The difference in maximal heart rate between the groups was -8.423 beats per minute and heart rate recovery in one minute (HRR-1) was -5.246 beats per minute. Maximal diastolic blood pressure, but not systolic pressure, was linked with OSA.

The differences in BMI (p<0.001) and in AHI (p=0.006) were associated with the change in HRR-1, but both VO2 and HRR-1 were independently linked with untreated OSA. And six-minute walk distance trended downward by -25.936 meters (p=0.056).

“Two studies were excluded from this analysis, since they involved pediatric patients with obstructive sleep apnea. However, even these 2 studies demonstrated that untreated obstructive sleep apnea is associated with reduced exercise capacity even after controlling for confounding variables," Dr. Singh added.

Dr. Nathaniel F. Watson, a sleep specialist at the University of Washington School of Medicine in Seattle, said, "This is another data point in a vast ocean of data points indicating the seriousness of sleep apnea to human health and well-being. The fact that this is a meta-analysis strengthens the conclusions because the authors were able to increase the sample size through that analytic technique and collapse a large amount of data into one concise conclusion."

Sleep apnea severely impairs nighttime sleep quality, so it’s not surprising that it would broadly impact our health and well-being, he told Reuters Health by phone.

"We sleep a third of our lives, so it must be important," he said. "We know sleep apnea is associated with increased risk of cardiovascular disease, obesity, and mental health issues. And now this evidence shows that it affects athletic performance through reduction in the oxygen extraction capacity of the human body."

"For clinicians, this study provides primary care providers with another discussion point with their patients to persuade them to take their sleep apnea symptoms seriously and be evaluated and treated through a board-certified sleep medicine physician. Indicating to patients for whom athletic performance is important that their exercise capacity is compromised may persuade them to pursue treatment," Dr. Watson suggested.

Sleep apnea is now a public health crisis, he warned.

"Right now, about 85% of sleep apnea in the world is undiagnosed or untreated. We believe that that equates to about 25 million Americans with moderate to severe sleep apnea," he explained.

"I would encourage physicians to ask their patients who complain of fatigue or tiredness, sleepiness, poor rest, or are irritable - symptoms of sleep apnea - questions about snoring, nocturnal choking and gasping, to help begin a conversation about their sleep health and get their sleep apnea identified and treated," Dr. Watson advised.

Dr. Singh said that he and his research team would like to learn "the true effect of obstructive sleep apnea on exercise capacity after controlling for other confounding variables (such as other medical comorbidities, smoking status, and alcohol use) that could not be included in this study."

His group is now planning a "meta-analysis of studies evaluating the effect of CPAP on exercise capacity in patients with OSA with the same exercise parameters as the present study," he added.

SOURCE: http://bit.ly/2sPMJwZ

SLEEP 2017.

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