Researchers from Monash University, the Alfred Hospital and Baker IDI Heart and Diabetes Institute conducted the first high-quality, randomised trial comparing the effect on OSA of surgical and medically-supervised weight loss in severely obese individuals.
The results, which show negligible statistical advantage of bariatric surgery in terms of treating OSA, are published in the Journal of the American Medical Association.
OSA is a condition affecting almost five per cent of the Australian population, in which a person stops breathing for periods of time during their normal sleep cycle. It is caused by obstruction to the upper airway by a floppiness or heaviness around the face and neck and in some patients, obesity is thought to be a cause of the condition.
Head of Obesity Research at Monash and Baker IDI, Associate Professor John Dixon, and Professor Matthew Naughton, a sleep specialist at Monash and Alfred Health, led the research.
Participants were recruited from sleep centres where they had been recently diagnosed with moderate to severe OSA and all had a Body Mass Index of between 35 and 55. Both groups – surgical and conventional weight loss – were followed up every four to six weeks for two years.
The participants who underwent laparoscopic adjustable gastric banding (LAGB) achieved an average two-year weight loss of approximately 20 per cent of their initial weight. The conventional group, who were provided with tailored dietary, exercise and behavioural programs, lost on average almost three per cent of their body weight over the two-year period.
Associate Professor Dixon said the dramatic differences in weight loss were not reflected in improvements in OSA, which was comprehensively monitored using polysomnography.
“Both groups experienced a reduction in OSA severity, but the difference between the surgical group and the conventional group was surprisingly small, given the weight loss disparity, and the majority still needed their CPAP machines during sleep,” Associate Professor Dixon said.
“Our research confirmed that weight loss is associated with reduction in OSA, but it’s a complex relationship. The effects vary greatly between individuals. It seems that the largest improvement in OSA, is associated with mild to moderate, rather than extreme weight loss.”
The researchers urged caution in advising patients on the benefits of weight loss for OSA reduction and that OSA therapies should be continued until the patient is properly assessed.