medwireNews: Obese patients with obstructive sleep apnea (OSA) who lose significant weight through surgery may still not be cured of their sleep disorder, study findings indicate.
This means that "caution should be used in counseling patients about the expected benefits of weight loss for OSA, and that patients losing weight be assessed appropriately before ceasing effective therapy," say John Dixon (Baker IDI Heart and Diabetes Institute, Melbourne, Australia) and team.
They found that despite bariatric surgery for weight loss resulting in a significantly greater mean weight loss among obese patients with OSA than conventional therapy, this did not necessarily translate into a significantly greater reduction in OSA severity.
"Our study did confirm that weight loss is associated with an improvement in AHI [apnea-hypopnea index], but we found great variability in the individual effect," the researchers explain in JAMA.
"The pattern of improvement in AHI suggests that much of the benefit is associated with mild-to-moderate weight loss, with limited additional benefit with further weight loss."
The researchers compared bariatric surgery and a conventional weight loss program using very low-calorie diets in 60 obese (body mass index >35 and <55 kg/m3) people who had been diagnosed with OSA (AHI of at least 20 events per hour) in the previous 6 months.
Two years later, surgery patients had lost a significant 22.7 kg more than conventional weight loss patients, at an average of 27.8 versus 5.1 kg.
This weight loss was associated with an improvement in AHI in both groups, decreasing by an average 25.5 events/hour among surgery patients and 14.0 events/hour among conventional weight loss patients.
The two groups did not differ with regard to continuous positive airway pressure (CPAP) therapy adherence or mean pressure delivered.
"Data from the present study (and that from systematic reviews) do not support routine cessation of CPAP or other therapies for OSA following bariatric surgery," the researchers state.
"Formal assessments, including polysomnography, should be considered before informing a patient that he or she may cease CPAP therapy."
They add: "The clinical picture can be confounded by patients self-reporting improved quality of life, sleepiness, sleep quality, and exercise tolerance after bariatric surgery."
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