Does liraglutide help sleep apnea? The SCALE Sleep Apnea trial

Why this study matters

Obstructive sleep apnea (OSA) is a condition where breathing stops and starts many times during sleep. It is strongly linked to a higher body weight, and losing weight has been shown to make it less severe. The usual treatment is a CPAP machine, which pushes air through a mask, but many people cannot use it or choose not to. SCALE Sleep Apnea asked whether liraglutide, a daily injectable weight-management medicine, could reduce the severity of OSA in these people. The trial had sites in Canada and the United States, so the participants are relevant to Canadian readers.

Who was in the study

The trial enrolled 359 adults with obesity who did not have diabetes. All had moderate OSA (15 to 29.9 breathing events per hour) or severe OSA (30 or more events per hour) and were unwilling or unable to use CPAP.

At the start, the mean age was 48.5 years, and 71.9% were men. The mean number of breathing events was 49.2 per hour, and 67.1% had severe OSA. Mean body weight was 117.6 kg, and mean body mass index (BMI, a number that compares weight with height) was 39.1. About two thirds (63.2%) had prediabetes, and the mean HbA1c, a blood test that shows average blood sugar over about three months, was 5.7%. The trial ran for 32 weeks.

What the researchers did

This was a randomized, double-blind trial. Randomized means chance decided the treatment. Double-blind means neither participants nor staff knew who got the medicine. Placebo is an injection with no active medicine.

180 people received liraglutide 3.0 mg by daily injection, and 179 received placebo. Both groups also followed a diet aimed at eating 500 fewer calories per day and received exercise counselling.

The primary outcome was the change in the apnea-hypopnea index (AHI), which counts how many times per hour breathing stops or becomes very shallow during sleep. Weight loss was also measured.

What they found

After 32 weeks, the AHI fell by a mean of 12.2 events per hour with liraglutide and 6.1 events per hour with placebo (R32-C83). The estimated difference was -6.1 events per hour, with a 95% confidence interval of -11.0 to -1.2. A confidence interval is the range in which the true difference most likely sits. This range does not include zero, so the benefit is unlikely to be due to chance, but the range is wide.

The abstract reports that people who lost more weight had bigger improvements in their sleep apnea measures. This was a post hoc analysis, meaning it was done after the trial ended rather than planned in advance. Liraglutide also produced greater reductions in HbA1c and systolic blood pressure than placebo, but the summary we reviewed does not give those numbers.

Side effects and people who stopped

The abstract states that the safety profile of liraglutide 3.0 mg was similar to that seen with the lower doses used for diabetes (1.8 mg or less). It does not list specific side effects with numbers.

According to the extracted data, 74% of the liraglutide group and 79% of the placebo group completed the trial. Side effects led to stopping treatment in 12% of the liraglutide group and 3% of the placebo group.

What this study does not tell you

• The trial lasted only 32 weeks. It does not show whether the improvement in sleep apnea lasts, or what happens after stopping.
• Everyone in the trial had chosen not to use CPAP or could not use it. The results do not compare liraglutide with CPAP, and do not apply to people who use CPAP.
• A reduction in AHI is a measurement outcome. The trial did not measure whether people felt less sleepy, had fewer accidents, or had fewer heart problems.
• People with diabetes were excluded.
• Both groups received diet and exercise support. The result shows what liraglutide added on top of that.
• The finding that a medicine improves a measured outcome in a trial is not the same as that medicine being approved for that use in Canada.
• The summary we reviewed does not state who funded the trial.

What it means in Canada

This trial included Canadian sites, so the participants are broadly similar to people seen in Canadian clinics. It does not say whether liraglutide is right for anyone with sleep apnea. To learn about the medicine, see liraglutide in Canada. For what provincial plans pay for, see public drug coverage by province. To see how weight-management programs differ, see compare services.

Related reading

Other studies in this library that bear on the same question.

Source