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Obstructive sleep apnoea

CPAP and weight loss lowers hypertension in obese patients

A reduction in brachial pulse pressure only reached statistical significance in the combination therapy arm
CPAP induced a reduction in central pulse pressure not seen from brachial pulse pressure measurements

Researchers from the Perelman School of Medicine at the University of Pennsylvania have reported that combining weight loss and continuous positive airway pressure (CPAP) therapy for patients with obstructive sleep apnoea also reduces hypertension.

Previous studies have examined the effects of weight loss and CPAP individually. However, this latest study presented at the 62nd Annual Scientific Session of the American College of Cardiology, San Francisco, is the first to exmain the incremental benefit of combination therapy (weight loss and CPAP therapy) over either therapy alone in obese patients with sleep apnoea.

“Obstructive sleep apnoea is present in a significant proportion of US adults, putting them at an increased risk for high blood pressure and heart disease,” said lead study author Dr Julio Chirinos, assistant professor of medicine at the University of Pennsylvania. “We need to find optimal ways to help these patient reduce their risk and improve their cardiovascular health. We found that the combination of weight loss and CPAP therapy is a better strategy to reduce blood pressure than either therapy alone.”

Study design

In the study, the authors screened 544 subjects in order to identify subjects with obesity, moderate-to-severe obstructive sleep apnoea (diagnosed using an overnight study in a sleep laboratory) and high levels of C-reactive protein (an inflammatory marker associated with heart disease). They randomised 181 subjects who met the inclusion criteria for the trial to one of three groups for 24 weeks:

  • CPAP therapy
  • A weight loss intervention (involving a dietary and lifestyle intervention)
  • A combination of the two interventions

The results showed that subjects randomised to CPAP alone did not experience weight loss, whereas subjects randomised to weight loss or combination therapy experienced a significant reduction in body weight and in their BMI.

To measure differences in hypertension across the groups, the researchers measured brachial systolic blood pressure and brachial pulse pressure in each group. In a subset of subjects, the authors also measured central (aortic) arterial pressure using arterial tonometry.

Over the course of the study, they then analysed the changes in blood pressure in all subjects. They also performed pre-specified analyses in the  patients who met the minimal compliance criteria for the CPAP and weight loss intervention.

After 24 weeks of therapy, reductions in brachial systolic pressure were observed in all three groups, whereas the reduction in brachial pulse pressure was only statistically significant in the combination therapy arm.

The reduction in brachial systolic blood pressure was significantly larger in the combination therapy arm (14.1mmHg) compared to either CPAP alone (3mmHg) or weight loss alone (6.8mmHg).

The researchers also found that CPAP induced a reduction in central pulse pressure, which was not evident from brachial pulse pressure measurements.

"These findings have important implications for cardiovascular risk reduction in this population," said Chirinos. "Therefore, more emphasis should be placed on not only addressing the sleep apnoea, but also treating the obesity in this patient population. It is also an important goal to find better ways to enhance compliance with CPAP therapy and weight loss interventions in these patients."

The additional authors involved in the study were Drs Indira Gurubhagavatula, Raymond Townsend, Karen Teff, Thomas Wadden, Daniel Rader, Alexandra L Hanlon, Greg Maislin, Jesse Chittam, Preston Broderick, Zeshan Ahmad, and Allan Pack.

The research was supported by grants from the National Institutes of Health and the American Heart Association National Clinical Research Award.

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