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From Medscape Medical News
Low-Energy Diet May Be Helpful in Obstructive Sleep Apnea
by Laurie Barclay, MD
June 21, 2011 — A very low-energy diet leads to improvements in moderate to severe obstructive sleep apnea in obese men, with benefits maintained at 1 year and proportional to weight loss and baseline severity, according to the results of a single-center, prospective, observational follow-up study reported online June 1 in the BMJ.
"Of all people with obstructive sleep apnea, an estimated 60-70% are either overweight or obese," write Kari Johansson, PhD student in the Obesity Unit, Department of Medicine at the Karolinska Institute in Stockholm, Sweden, and colleagues. "Given the close association between obstructive sleep apnoea and obesity, weight loss has been advocated as a primary treatment option in obese patients with sleep apnoea.... Despite an improving case for the robust treatment effect of weight loss in obstructive sleep apnoea, concerns remain regarding the long term maintenance of improvements, especially after rapid weight loss with a very low energy diet."
The goal of the study was to evaluate whether initial improvements in obstructive sleep apnea after a very low-energy diet were maintained after 1 year in patients with moderate to severe disease. At an outpatient obesity clinic in a university hospital in Stockholm, 63 men aged 30 to 65 years were enrolled. Body mass index was 30 to 40 kg/m2, and patients had moderate to severe obstructive sleep apnea treated with continuous positive airway pressure, with an apnea-hypopnea index of at least 15 events/hour (mean, 36 events/hour).
Participants were enrolled in a 1-year weight loss program in which they were given a very low-energy diet (2.3 MJ/day) for 7 weeks, followed by 2 weeks of gradual introduction of normal food and then by a weight loss maintenance program. The primary study endpoint was severity of obstructive sleep apnea as measured by the apnea-hypopnea index. Analysis was performed on all patient data, with baseline carried forward for missing data.
Of 63 patients enrolled, 58 completed the very low-energy diet and began the weight maintenance program, and 44 completed the full program. At 1 year, 49 patients had complete measurements. After completing the very low-energy diet period, participants had mean improvements of −21 events/hour in the apnea-hypopnea index (95% confidence interval [CI] −17 to −25) and −18 kg in weight (95% CI, −16 to −19; both P < .001). After 1 year, improvement from baseline was −17 events/hour in the apnea-hypopnea index (95% CI, −13 to −21) and −12 kg in body weight (95% CI, −10 to −14; both P < .001).
Improvements in the apnea-hypopnea index were greater in patients with severe obstructive sleep apnea at baseline (−25 events/hour) vs patients with moderate disease (−7 events/hour, P < .001). At 1 year, continuous positive airway pressure was no longer needed in 30 of 63 patients (48%; 95% CI, 35% - 60%), and 6 patients (10%; 95% CI, 2% - 17%) had total remission of obstructive sleep apnea, defined as an apnea-hypopnea index of less than 5 events/hour.
Limitations of this study include observational design, lack of a control group, use of a portable diagnostic device instead of a polysomnography to detect obstructive sleep apnea, lack of generalizability to women, and follow-up limited to 1 year.
"There was a dose-response association between weight loss and apnoea-hypopnoea index at follow-up (β=0.50 events/kg, 0.11 to 0.88; P=0.013)," the study authors write. "Initial improvements in obstructive sleep apnoea after treatment with a very low energy diet can be maintained after one year in obese men with moderate to severe disease. Those who lose the most weight or have severe sleep apnoea at baseline benefit most."
Cambridge Weight Plan, Northants, United Kingdom, and Novo Nordisk AS, Bagsværd, Denmark, supported this study. Some of the study authors have disclosed various financial relationships with Cambridge Weight Plan.
BMJ. 2011;342:d3017. Full text
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