OBESITY: Sleep Apnea Cut With Weight-Loss Program
By Todd Neale, Senior Staff Writer,
October 06, 2011
Action Points
Note that this study was published as an abstract and presented at a conference. These data and conclusions should be considered to be preliminary until published in a peer-reviewed journal.
Explain that patients with obesity and type 2 diabetes participating in a sleep substudy lost significantly more weight with an intensive lifestyle intervention program than those in the control group and also significantly reduced their apnea-hypopnea index.
Note that improved apnea-hypopnea index tracked with the amount of weight lost but still remained significantly improved for the lifestyle intervention group compared with controls at four years despite gaining back about half the weight lost in the first year.
Review
ORLANDO -- An intensive lifestyle intervention to get obese patients with type 2 diabetes to lose weight had long-lasting effects on obstructive sleep apnea as well, according to results from an ancillary study to the Look AHEAD trial.
Through four years, patients undergoing the intensive intervention maintained about a four-point reduction in apnea-hypopnea index, compared with a sustained four-point increase in the control group, according to Gary Foster, PhD, of Temple University in Philadelphia.
Patients with the most severe obstructive sleep apnea at baseline had the largest gains through four years (P<0.0001), he reported at the Obesity Society meeting here.
Foster noted, however, that with a mean apnea-hypopnea index of 20.5 -- indicating moderate obstructive sleep apnea -- at baseline among the patients, the reductions seen over the course of the study would not, on average, be enough to replace other treatments.
"I don't want to give you the impression that this is an alternative treatment to [continuous positive airway pressure]," he said. "It's probably a complementary treatment."
The findings came from Sleep AHEAD, an ancillary study of the Look AHEAD trial, which compared an intensive lifestyle intervention with diabetes support and education for weight loss in obese patients with type 2 diabetes.
The sleep study was designed to evaluate whether weight loss would be associated with improvements in sleep-disordered breathing, which had been demonstrated in observational studies and smaller randomized trials.
Participants in Look AHEAD were screened with a questionnaire designed to identify patients at increased risk for obstructive sleep apnea. The researchers excluded patients currently being treated for the condition or who had undergone surgery for it, but included those with untreated obstructive sleep apnea.
All 305 patients selected for the sleep study underwent overnight polysomnograms at home. Those with an apnea-hypopnea index of less than 5 were considered free from obstructive sleep apnea. Scores of 5 to less than 15 were considered mild, 15 to less than 30 moderate, and 30 or more severe.
The mean score was 20.5. Only 13.4% of the patients did not have obstructive sleep apnea. Another 33.5%, 30.5%, and 22.6% had mild, moderate, and severe symptoms, respectively.
After one year, patients undergoing the intensive lifestyle intervention lost an average of 24 pounds, whereas those in the control group had no weight loss (P<0.0001).
At the same time, patients in the intervention group had about a six-point reduction in apnea-hypopnea index, compared with a four-point increase in the controls (P<0.0001).
Through four years, patients in the intervention group gained back about half of the weight that was lost, although they sustained a four-point reduction in apnea-hypopnea index. The controls sustained a four-point increase in the index.
At four years, a greater percentage of patients in the intervention group improved their obstructive sleep apnea category from baseline (about 40% versus 15%) and had a remission of apnea symptoms (20% versus 3%).
Although the change in apnea-hypopnea index was significantly related to the weight change, there was still a significant reduction in symptoms even after the change in weight was accounted for (P=0.001).
That indicates that the intervention had an effect on obstructive sleep apnea that was separate from the weight loss, Foster said.
"The likely hero, I think, is fitness," he said, noting that another study has shown that even in the absence of weight loss, changes in fitness can drive changes in apnea-hypopnea index.