Review: In patients with obstructive sleep apnea, continuous positive airway pressure increases weight Clinical impact ratings:


Drager LF, Brunoni AR, Jenner R, et al. Effects of CPAP on body weight in patients with obstructive sleep apnoea: a meta-analysis of randomised trials. Thorax. 2015;70:258 – 64.




In patients with obstructive sleep apnea (OSA), what is the effect of continuous positive airway pressure (CPAP) on weight?

In this meta-analysis of 25 RCTs of predominately obese, middle-aged men with moderate to severe OSA, Drager and colleagues show that a median 3 months of CPAP leads to a small, but statistically significant, increase in BMI and weight. Any amount of weight gain is not welcome in obese patients, although the actual amount was small (0.42 kg). This is probably not a clinically significant increase, and its effect on long-term health is unclear.

Review scope Included studies compared CPAP with sham or no treatment for ≥ 4 weeks in patients ≥ 18 years of age who had OSA. Comparisons of CPAP with active lifestyle or drug interventions were excluded. Outcomes were changes in body mass index (BMI) and weight.

Review methods MEDLINE, SCOPUS, and Cochrane Central Register (all to Oct 2013) and reference lists were searched for randomized controlled trials (RCTs); experts were contacted. 25 RCTs (n = 3181, mean age 53 y, 84% men, baseline BMI 31 kg/m2, median study duration 3 mo) met selection criteria. All trials were of good quality (mean score 7/9).

Main results Meta-analysis showed that CPAP increased BMI and weight compared with control (Table).

Conclusion In patients with obstructive sleep apnea, continuous positive airway pressure increases body mass index and weight compared with sham or no treatment. Source of funding: Fundac¸a˜o de Amparo a` Pesquisa do Estado de Sa˜o Paulo. For correspondence: Dr. Luciano Drager, University of Sa˜ o Paulo Medical School, Sa˜ o Paulo, Brazil. E-mail [email protected] 

CPAP has several benefits in OSA. Positive airway pressure stabilizes breathing patterns and improves blood pressure; sleepiness; and several quality-of-life, cognitive, and depression measures (1). These positive outcomes probably offset any potential negative consequences from the small additional weight gain, especially in patients with moderate to severe OSA. Interestingly, children with OSA treated by adenotonsillectomy gained weight after surgery (2), suggesting that weight gain may be a function of treating OSA rather than CPAP itself. Many clinicians counsel their patients that CPAP may help weight-loss efforts. The results of this meta-analysis suggest otherwise. Obese patients with mild and asymptomatic OSA may benefit from weight-loss efforts alone because dietary interventions and subsequent weight loss reduce OSA in patients with mild disease (3). A recent RCT found beneficial effects of combined weight loss and CPAP therapy on blood pressure and surrogate cardiovascular biomarkers (4). Similarly, the review by Drager and colleagues reminds us of the importance of weight loss measures as a cornerstone of OSA therapy, regardless of other therapeutic options used. CPAP cannot and should not be a substitute for the long-term benefits of sustained weight loss. Shirin Shafazand, MD, MS University of Miami Miami, Florida, USA References

Continuous positive airway pressure (CPAP) vs sham or no treatment (control) in patients with obstructive sleep apnea*

1. Giles TL, Lasserson TJ, Smith BH, et al. Continuous positive airways pressure for obstructive sleep apnoea in adults. Cochrane Database Syst Rev. 2006;(3):CD001106.


2. Katz ES, Moore RH, Rosen CL, et al. Growth after adenotonsillectomy for obstructive sleep apnea: an RCT. Pediatrics. 2014;134:282-9.

Number of trials (n)

Change from baseline

At a median 3 mo

CPAP Control SMD (95% CI) Body mass index (kg/m2)

25 (3181)



0.14 (0.07 to 0.21)

Weight (kg)

25 (3181)



0.17 (0.10 to 0.24)

*SMD = standard mean difference; other abbreviations defined in Glossary. Standardized effect size determined using Hedges' g; meta-analysis used a fixed-effect model.

姝 2015 American College of Physicians


3. Tuomilehto HP, Seppa¨ JM, Partinen MM, et al; Kuopio Sleep Apnea Group. Lifestyle intervention with weight reduction: first-line treatment in mild obstructive sleep apnea. Am J Respir Crit Care Med. 2009;179:320-7. 4. Chirinos JA, Gurubhagavatula I, Teff K, et al. CPAP, weight loss, or both for obstructive sleep apnea. N Engl J Med. 2014;370:2265-75.

ACP Journal Club

Annals of Internal Medicine

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21 April 2015

ACP Journal Club: review: in patients with obstructive sleep apnea, continuous positive airway pressure increases weight.

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