FROM CHEST

Continuous positive airway pressure (CPAP) therapy for obstructive sleep apnea (OSA) has a significant beneficial effect on blood pressure, according to an analysis of participants in three randomized controlled trials.

Previous meta-analyses suggested that CPAP treatment led to an average of improvement of 2-3 mm Hg, but the estimates relied on heterogeneous trials that often had low levels of CPAP adherence, and those factors might have led to an underestimation of the treatment effect. The new analysis showed that halting CPAP increases blood pressure between 5.0 and 9.0 mm Hg, compared with patients who continued using CPAP ( Chest. 2016;150[6]:1202-10 ).

To get around the problem of adherence, researchers led by Malcolm Kohler, MD, at University Hospital of Zürich analyzed the results of three previous studies looking at the effects of CPAP withdrawal. The analysis included 153 OSA patients on CPAP therapy, who had been randomized to continue therapy or to withdraw from therapy for 2 weeks. Eighty-seven of these patients discontinued CPAP, and the remaining 66 patients continued the therapy. Blood pressure was measured at home and in hospital.

On average, those who discontinued CPAP had an increase in office systolic blood pressure of 5.4 mm Hg (95% confidence interval, 1.8-8.9 mm Hg; P = .003) and an increase in home systolic blood pressure of 9.0 mm Hg (95% CI, 5.7-12.3 mm Hg; P less than .001), compared with patients who continued CPAP. The effects of stopping CPAP, instead of continuing the therapy, on office diastolic blood pressure and home diastolic pressure were increases of 5.0 mm Hg (95% CI, 2.7-7.3 mm Hg; P less than .001) and 7.8 mm Hg (95% CI, 5.6-10.0 mm Hg; P less than .001), respectively.

Patients who discontinued CPAP also experienced a significant increase in apnea-hypopnea index, from 2.8/h to 33.2/h, while those who continued using CPAP, on average, experienced only a 0.3/h increase in apnea-hypopnea index from baseline.

“One clinical implication is that if you do not need to stop CPAP for obstructive sleep apnea, do not stop it. This study also suggests the importance of monitoring your blood pressure in a home setting, under usual conditions,” summed up Robert Kloner, MD, PhD, director of the Huntington Medical Research Institutes Cardiovascular Research Lab, Pasadena, Calif., who was not involved in the study.

Previous studies of CPAP, such as the SAVE study published in the New England Journal of Medicine in September ( N Engl J Med. 2016;375:919-31 ), often find little or no connection between CPAP therapy and cardiovascular outcomes. That is probably because of inadequate adherence to CPAP therapy. “That’s always been the bane of sleep apnea studies,” said Krishna M. Sundar, MD, FCCP, who also did not participate in the study.

The current work got around the problem by looking at patients who had already established use of CPAP. “This is a very good study,” said Dr. Sundar, who is the medical director of the Sleep-Wake Center at the University of Utah, Salt Lake City.

The study was funded by the Swiss National Science Foundation and the University of Zürich. The analysis’ authors and the outside experts quoted in this story reported no financial disclosures.

chestphysician@frontlinemedcom.com

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