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Longer term effects of very low energy diet on obstructive sleep apnoea in cohort derived from randomised controlled trial: prospective observational follow-up study

BMJ 2011; 342 doi: http://dx.doi.org/10.1136/bmj.d3017 (Published 01 June 2011) Cite this as: BMJ 2011;342:d3017
  1. Kari Johansson, PhD student1,
  2. Erik Hemmingsson, postdoctoral research fellow1,
  3. Richard Harlid, physician2,
  4. Ylva Trolle Lagerros, physician13,
  5. Fredrik Granath, statistican3,
  6. Stephan Rössner, professor1,
  7. Martin Neovius, associate professor3
  1. 1Obesity Unit, Department of Medicine (Huddinge), Karolinska Institute, SE-141 86 Stockholm, Sweden
  2. 2Aleris Fysiologlab, Stockholm
  3. 3Clinical Epidemiology Unit, Department of Medicine (Solna), Karolinska Institute, Stockholm
  1. Correspondence to: K Johansson kari.johansson{at}ki.se
  • Accepted 7 April 2011

Abstract

Objective To determine whether initial improvements in obstructive sleep apnoea after a very low energy diet were maintained after one year in patients with moderate to severe obstructive sleep apnoea.

Design Single centre, prospective observational follow-up study.

Setting Outpatient obesity clinic in a university hospital in Stockholm, Sweden.

Participants 63 men aged 30-65 with body mass index (BMI) 30-40 and moderate to severe obstructive sleep apnoea defined as an apnoea-hypopnoea index ≥15 (events/hour), all treated with continuous positive airway pressure.

Intervention A one year weight loss programme, consisting of an initial very low energy diet for nine weeks (seven weeks of 2.3 MJ/day and two weeks of gradual introduction of normal food) followed by a weight loss maintenance programme.

Main outcome measure Apnoea-hypopnoea index, the main index for severity of obstructive sleep apnoea. Data from all patients were analysed (baseline carried forward for missing data).

Results Of 63 eligible patients, 58 completed the very low energy diet period and started the weight maintenance programme and 44 completed the full programme; 49 had complete measurements at one year. At baseline the mean apnoea-hypopnoea index was 36 events/hour. After the very low energy diet period, apnoea-hypopnoea index was improved by −21 events/hour (95% confidence interval −17 to −25) and weight by −18 kg (−16 to −19; both P<0.001). After one year the apnoea-hypopnoea index had improved by −17 events/hour (−13 to −21) and body weight by −12 kg (−10 to −14) compared with baseline (both P<0.001). Patients with severe obstructive sleep apnoea at baseline had greater improvements in apnoea-hypopnoea index (−25 events/hour) compared with patients with moderate disease (−7 events/hour, P<0.001). At one year, 30/63 (48%, 95% confidence interval 35% to 60%) no longer required continuous positive airway pressure and 6/63 (10%, 2% to 17%) had total remission of obstructive sleep apnoea (apnoea-hypopnoea index <5 events/hour). 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).

Conclusion 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.

Trial registration Current Controlled Trials 70090382.

Footnotes

  • We thank the study nurse Lena Mannström and the dietitians Jenny Dygve and Mary Hyll for treating all patients, and the nurses Anna Laumann, Viveca Petré, and Sara Yllö for assistance during the study.

  • Contributors: KJ, MN, SR, and EH conceived the study hypothesis. SR and YTL met all the patients, RH conducted the sleep studies, and KJ and MN conducted the statistical analyses. KJ wrote the first draft of the manuscript. MN, EH, SR, YTL, RH, and FG critically reviewed and contributed to the final draft. All authors are guarantors.

  • Funding: This study was partly supported by research grants from Cambridge Weight Plan, Northants, UK, and Novo Nordisk AS, Bagsværd, Denmark. No one representing the funding sources read or commented on any version of the manuscript.

  • Competing interests: All authors have completed the Unified Competing Interest form at www.icmje.org/coi_disclosure.pdf (available on request from the corresponding author) and declare: KJ, SR, and EH have received travel grants from Cambridge Weight Plan to attend a scientific meeting; no other relationships or activities that could appear to have influenced the submitted work.

  • Ethical approval: This study was approved by the regional ethics committee in Stockholm, Sweden. Written informed consent was obtained from all patients.

  • Data sharing: No additional data available.

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