Among patients with obstructive sleep apnea and hypertension that requires three or more medications to control, continuous positive airway pressure treatment for 12 weeks resulted in a decrease in 24-hour average and diastolic blood pressure and an improvement in the nocturnal blood pressure pattern, compared with patients who did not receive CPAP, according to a Spanish study.
Systemic hypertension is one of the most treatable cardiovascular risk factors, according to background information in the study, which was published in the Dec. 11 issue of the Journal of the American Medical Association. Researchers noted 12% to 27% of all hypertensive patients require at least three antihypertensive drugs for adequate blood pressure control and are considered to have resistant hypertension, meaning they are almost 50% more likely to experience a cardiovascular event than hypertensive patients without resistant hypertension.
The incidence of resistant hypertension is expected to increase, the authors noted.
Recent studies have shown that obstructive sleep apnea may contribute to poor control of blood pressure and that more than 70% of resistant hypertension patients have OSA. Continuous positive airway pressure is the treatment of choice for severe or symptomatic OSA.
A meta-analysis suggests that CPAP treatment reduces blood pressure levels to a clinically meaningful degree, but whether this positive effect is more pronounced in patients with resistant hypertension is unclear because studies on this issue are scarce and based on single-center approaches, the authors wrote.
Methodology and results
Miguel-Angel Martinez-Garcia, MD, PhD, of the Hospital Universitario y Politecnico La Fe, Valencia, Spain, and colleagues assessed the effect of CPAP treatment on blood pressure levels and nocturnal blood pressure patterns of 194 patients with resistant hypertension and OSA. The trial was conducted in 24 teaching hospitals in Spain, with data collected from June 2009 to October 2011. The patients randomly were assigned to receive CPAP or no CPAP while maintaining usual blood pressure control medication.
When the changes in blood pressure during the study period were compared between study groups by intention-to-treat, the CPAP group achieved a 3.1 mm Hg greater decrease in 24-hour average blood pressure and 3.2 mm Hg greater decrease in 24-hour diastolic blood pressure. The difference in change in 24-hour systolic blood pressure was not statistically significant compared with the control group.
In addition, the percentage of patients displaying a nocturnal blood pressure dipper pattern (a decrease of at least 10% in the average night-time blood pressure compared with the average daytime blood pressure) at the 12-week follow-up was greater in the CPAP group than in the control group (35.9% vs. 21.6%). There was a positive correlation between hours of CPAP use and the decrease in 24-hour average blood pressure.
Further research is warranted to assess longer-term health outcomes, the authors wrote.
Study abstract: http://jama.jamanetwork.com/article.aspx?articleid=1788459