What is the clinical evidence from this study?

Study design: RCT. Population: Obstructive sleep apnea (OSA) with obesity (n=60). Intervention: Weight loss (bariatric surgery or very low calorie diet) vs. Baseline. Primary outcome: Percentage change in nonsupine AHI compared to supine AHI (p=.05).

April 21, 2017Open Access

Improvement in Obstructive Sleep Apnea With Weight Loss is Dependent on Body Position During Sleep

Key Result

Weight loss resulted in a greater percentage reduction in nonsupine AHI (-54.0%) compared to supine AHI (-33.1%, p=0.05), normalizing nonsupine AHI in 22% of patients.

Study Design

Type

RCT (n=60)

Randomization

randomized

Structured PICO

Does weight loss differentially reduce nonsupine AHI compared to supine AHI in obese patients with OSA?

Population

60 obese participants (BMI >35 and <55) with recently diagnosed OSA and AHI ≥ 20 events/hour, randomized to bariatric surgery vs. medical weight loss, followed for 2 years.

Intervention

Weight loss via very low calorie diet with regular review or laparoscopic adjustable gastric banding

Comparator

None (comparison of supine vs nonsupine AHI changes within the weight loss cohort)

Outcome

Reduction in nonsupine apnea/hypopnea index (AHI) compared with supine AHI at 2 yearssurrogate

Weight loss in obese patients with OSA leads to a greater reduction in nonsupine AHI compared to supine AHI, normalizing nonsupine AHI in 22% of patients and suggesting supine sleep avoidance may be curative for this subset.

Main Result

Absolute Event Rate: -54% vs -33.1%

p-value: p=.05

Abstract

Study Objectives: Weight loss fails to resolve obstructive sleep apnea (OSA) in most patients; however, it is unknown as to whether weight loss differentially affects OSA in the supine compared with nonsupine sleeping positions. We aimed to determine if weight loss in obese patients with OSA results in a greater reduction in the nonsupine apnea/hypopnea index (AHI) compared with the supine AHI, thus converting participants into supine-predominant OSA. Methods: Post hoc analysis of data from a randomized controlled trial assessing the effect of weight loss (bariatric surgery vs. medical weight loss) on OSA in 60 participants with obesity (body mass index: >35 and <55) with recently diagnosed (<6 months) OSA and AHI of ≥ 20 events/hour. Patients were randomized to very low calorie diet with regular review (n = 30) or to laproscopic adjustable gastric banding (n = 30) with follow-up sleep study at 2 years. Results: Eight of 37 (22%) patients demonstrated a normal nonsupine AHI (<5 events/hour) on follow-up compared to 0/37 (0%) patients at baseline (p = .003). These patients were younger (40.0 ± 9.6 years vs. 48.4 ± 6.5 years, p = .007) and lost significantly more weight (percentage weight change -23.0 -21.0 to -31.6% vs. -6.9 1.9 to -17.4, p = .001). The percentage change in nonsupine AHI was greater than the percentage change in supine AHI (-54.0 -15.4 to -87.9% vs -33.1 -1.8 to -69.1%, p = .05). However, the change in absolute nonsupine AHI was not related to change in absolute supine AHI (p = .23). Conclusions: Following weight loss, a significant proportion (22%) of patients with obesity have normalization of the nonsupine AHI. For these patients, supine sleep avoidance may cure their OSA.