Increased BMI in Patients With Obstructive Sleep Apnea After CPAP Treatment

An overweight man sleeping
An overweight man sleeping
In patients with obstructive sleep apnea, BMI values increased significantly following CPAP therapy.

In patients with obstructive sleep apnea (OSA), body mass index (BMI) values increased significantly following continuous positive airway pressure (CPAP) therapy, particularly among those with CPAP use of 5 hours or less per night, those without cardiovascular disease, and/or those with dysglycemia at baseline, according to the results of a meta-analysis of randomized controlled trials (RCTs) published in Annals of the American Thoracic Society.

Investigators sought to examine the effects of CPAP treatment on BMI and local adiposity, along with the potential modifiers of CPAP outcomes on BMI in patients with OSA. The inclusion criteria for the meta-analysis were as follows: (1) studies that recruited adult patients with OSA (≥18 years of age); (2) RCTs with a CPAP group and a control group (either sham CPAP or usual care treatment) with follow-up of at least 4 weeks; (3) studies that reported mean and standard deviation/standard error of BMI both before and after intervention; and (4) no language restriction.

A total of 39 RCTs that included 6954 participants comprised the meta-analysis. Per intention-to-treat analysis, BMI increased significantly following CPAP therapy vs control treatment (weighted mean difference [WMD], 0.148 kg/m2; 95% CI, 0.035-0.262; P =.010). In the studies in which an increase in BMI was noted, waist and neck circumferences were also significantly larger.

Per subgroup analysis, increased BMI levels were associated with CPAP use of 5 hours or less per night (WMD, 0.231) but not with CPAP use of more than 5 hours per night (WMD, 0.001; between-group P =.049). Additionally, BMI increased significantly in participants without cardiovascular disease at baseline (WMD, 0.200) but decreased significantly in those with cardiovascular disease at baseline (WMD, 0.188; between-group P< .001). BMI also increased significantly in patients with dysglycemia at baseline (WMD, 0.499) but not among those without dysglycemia at baseline (WMD, 0.100; between-group P= .032).

A major limitation of the study is the fact that heterogeneity was high, which might be attributable to differences in CPAP adherence among participants, as well as to the presence or absence of concomitant cardiovascular disease and dysglycemia among the various studies.

The researchers concluded that enhancement of CPAP adherence and weight management should be encouraged in patients with OSA, to improve cardiovascular outcomes. Hopefully, future studies will elucidate the underlying mechanisms of BMI changes following CPAP therapy in both the short-term and the long-term period.

Disclosure: Several study authors declared affiliations with the pharmaceutical industry. Please see the original reference for a full list of authors’ disclosures.


Chen B, Drager LF, Peker Y, et al. Effect of CPAP on weight and local adiposity in adults with obstructive sleep apnea: a meta-analysis.  Ann Am Thorac Soc. Published online March 19, 2021. doi:10.1513/AnnalsATS.202101-060OC