From the Journals

Long-term CPAP use not linked to weight gain

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Strong study, hard to extrapolate

This analysis of the Sleep Apnea Cardiovascular Endpoints (SAVE) trial had several strengths and a reassuring conclusion regarding lack of weight gain with long-term use of CPAP in patients with obstructive sleep apnea (OSA) and comorbid cardiovascular disease. However, the findings may be difficult to extrapolate to Western countries, according to authors of an editorial.

“It is conceivable that the results of the study would have been different if the predominant race of the participants had been Caucasian and had a higher BMI,” said Rohit Budhiraja, MBBS, and Stuart F. Quan, MD, in the editorial. Two-thirds of the patients in the were enrolled in China, the authors said, noting that it is “well established” that Asians with OSA are less often obese compared with Caucasians with OSA in Western countries.

For clinicians, the most important message of this analysis of the SAVE trial should be that weight loss did not occur, according to Dr. Budhiraja and Dr. Quan.

“A comprehensive approach to weight loss should be used, instead of the optimistic view that improved sleep quality and daytime symptoms will automatically translate into increase physical activity, better nutrition and weight loss,” they concluded in their editorial.

Dr. Budhiraja is affiliated with the Brigham and Women’s Hospital, and Harvard Medical School, both in Boston; Dr. Quan is affiliated with Harvard Medical School, Boston, and the University of Arizona Tucson. Their editorial appears in Chest ( 2019 Apr;155[4] 657-8 ). Dr. Budhiraja reported no conflicts of interest. Dr. Quan reported serving as a consultant for Jazz Pharmaceuticals and Best Doctors, along with grant funding from the National Institutes of Health.



Continuous positive airway pressure (CPAP) over several years did not lead to clinically concerning levels of weight gain among patients with obstructive sleep apnea and comorbid cardiovascular disease enrolled in a large international trial, findings from a large, multicenter trial show.

CPAP machine for obstructive sleep apnea is shown. Courtesy ResMed

No differences in weight, body mass index (BMI), or other body measurements were found when comparing CPAP and control groups in a post hoc analysis of the Sleep Apnea Cardiovascular Endpoints (SAVE) trial, which included 2,483 adults enrolled at 89 centers in seven countries.

In a subanalysis, there was a small but statistically significant weight gain of less than 400 g in men who used CPAP at least 4 hours per night as compared to matched controls. However, there were no differences in BMI or neck and waist circumferences for these men, and no such changes were observed in women, according to the investigators, led by Qiong Ou, MD, of Guangdong (China) General Hospital and R. Doug McEvoy, MD, of the Adelaide Institute for Sleep Health at Flinders University, Adelaide, Australia.

“Such a small change in weight, even with good adherence over several years, is highly unlikely to have any serious clinical ramifications,” wrote the investigators of the study published in Chest.

“Taken together, these results indicate that long-term CPAP treatment is unlikely to exacerbate the problems of overweight and obesity that are common among patients with OSA,” they added.

In a previous meta-analysis of randomized trials, investigators concluded that CPAP promoted significant increases in BMI and weight. However, the median study duration was only 3 months.

In contrast, the analysis of the SAVE trial included adults who had regular body measurements over a mean follow-up of nearly 4 years.

That long-term follow-up provided an “ideal opportunity” to assess whether CPAP treatment promotes weight gain in OSA patients over the course of several years, the authors of the SAVE trial analysis wrote.

For men in the SAVE trial, the difference in weight change for the CPAP group vs. the control group was just 0.07 kg (95% confidence interval, –0.40 to 0.54; P = .773) while in women, the difference for CPAP vs. controls was –0.14 kg (95% CI, –0.37 to 0.09; P = .233), the investigators reported.

Weight gain was significantly higher among men with good CPAP adherence, defined as use for at least 4 hours per night, investigators said, noting a mean difference of 0.38 kg (95% CI, 0.04-0.73; P = .031), though no other differences were found in body measurements for men, and no such associations were found in women with good CPAP adherence.

It’s not exactly clear why this SAVE analysis would find no evidence of CPAP promoting weight gain over the long term, in contrast to the earlier meta-analysis of short-term studies finding a significant risk of weight gain.

However, it is possible that differences in study populations such as ethnicity, age, or comorbidities contributed to the differences, said investigators.

For example, results of regression analysis in the present study showed that, compared with recruitment in Australia, recruitment in China and India was significantly linked to weight loss, while recruitment in New Zealand was linked to weight gain.

Dr. Ou had no disclosures related to the study, while Dr. McEvoy reported disclosures related to Philips Respironics, ResMed, Fisher & Paykel, Air Liquide, and the National Health and Medical Research Council of Australia.

SOURCE: Ou Q et al. Chest. 2019 Apr;155(4):720-9.

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