By Megan Rauscher

NEW YORK (Reuters Health) - In people who are obese, weight-loss surgery will likely lead to an improvement in obstructive sleep apnea (OSA) but it won't eliminate the nighttime breathing disorder. Many patients will have residual OSA one year after weight-loss surgery (also known as bariatric surgery), results of a study indicate.

"There are numerous benefits to weight loss by any means, (including) a reduction in the severity of OSA," study leader Dr. Christopher Lettieri of Walter Reed Army Medical Center in Washington, DC, told Reuters Health. "However, patients and their physicians should understand that OSA can occur in the absence of obesity, and losing weight, even if substantial, may not resolve OSA."

OSA is a common problem, particularly among the obese, in which tissues in the back of the throat temporarily collapse during sleep causing numerous, brief episodes of interrupted breathing. It can be effectively treated with a special "CPAP" breathing device that alleviates the blockage by pushing air into throat.

In a study designed to clarify the impact of bariatric surgery on OSA, 24 morbidly obese patients underwent overnight sleep studies before and 1 year after bariatric surgery.

All of them had OSA at the start of the study and surgical weight loss resulted in substantial improvements in the severity of OSA, Lettieri and colleagues report in the Journal of Clinical Sleep Medicine.

However, all but one patient had persistent OSA despite their weight loss. "In fact, the majority still had moderate to severe disease, which would require continued treatment," Lettieri said. Two people had a worsening of their OSA despite significant weight loss.

"OSA," Lettieri said, "is associated with numerous adverse effects on health and quality of life, especially in those with moderate to severe disease. If present, it should be treated."

Patients having weight-loss surgery, he added, should not assume their OSA has resolved and should have a repeat sleep study prior to discontinuing their OSA treatment.

SOURCE: Journal of Clinical Sleep Medicine, August 15, 2008.

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