Higher-risk patients benefit more in BP reduction from CPAP
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Patients with low oxygen saturation, more severe sleep apnea and higher baseline BP achieved the greatest reductions in BP after use of continuous positive airway pressure, according to data published in Hypertension.
As Healio previously reported, in an intention-to-treat analysis, patients in the HIPARCO trial with obstructive sleep apnea (OSA) and treatment-resistant hypertension who received continuous positive airway pressure (CPAP) for 12 weeks had reduced mean BP and diastolic BP compared with those who did not; however, CPAP did not affect systolic BP.
“The effects of a treatment can vary depending on several different factors. The prior identification of the clinical phenotypes of responders, based on patients’ baseline characteristics, could therefore help clinicians tailor their treatment and practice precision medicine,” Miguel-Angel Martínez-García, MD, PhD, of the Hospital Universitario y Politécnico La Fe in Valencia, Spain, and Martino F. Pengo, MD, PhD, of the IRCCS Istituto Auxologico Italiano in Milan, wrote. “So, the aim of this study was to identify potential clinical phenotypes of responders among patients with resistant hypertension with OSA and good adherence to CPAP.”
For this post hoc analysis of the HIPARCO trial, a BP responsive reduction was defined as a drop of 5 mm Hg or more in 24-hour-systolic BP, 4 mm Hg or more in 24-hour diastolic BP, 4 mm Hg or more in nocturnal systolic BP and 2 mm Hg or more in nocturnal diastolic BP. Researchers also evaluated predictors of change from a nondipper/riser pattern to a dipper BP pattern.
This analysis included 71 HIPARCO participants (mean age, 58 years) who showed good adherence to CPAP, defined as average daily usage of at least 4 hours per day.
Variables of interest included age, sex, obesity, baseline BP, number of antihypertensive drugs, previous CV events, Epworth Sleepiness Scale of more than 10, presence of severe OSA and nighttime spent with an oxygen saturation below 90%.
Factors associated with BP lowering
According to the study, oxygen saturation below 90% was the only variable associated with all BP responsive factors:
- 24-hour systolic BP (OR = 1.06; 95% CI, 1.02-1.1; P = .014);
- 24-hour diastolic BP (OR = 1.04; 95% CI, 1.02-1.3; P = .022);
- nocturnal systolic BP (OR = 1.06; 95% CI, 1.01-1.1; P = .022);
- nocturnal diastolic BP (OR = 1.04; 95% CI, 1-1.1; P =.045); and
- change in BP nocturnal pattern (OR = 1.06; 95% CI, 1.03-1.1; P = .036).
Baseline BP values were associated only with 24-hour systolic BP (OR = 1.12; 95% CI, 1.1-1.3; P = .002) and 24-hour diastolic BP reduction (OR = 1.06; 95% CI, 1-1.3; P = .017).
The presence of severe OSA was associated with changes in nocturnal systolic BP (OR = 3.4; 95% CI, 1.27-5.6; P = .042), nocturnal diastolic BP (OR = 6.33; 95% CI, 2.1-7.6; P = .019) and the recovery of a dipper nocturnal pattern (OR = 5.27; 95% CI, 2.4-8.3; P = .012).
“It is important to note that baseline BP levels were independently associated with better response to CPAP in 24-hour BP values in our study,” the researchers wrote. “Some authors have claimed that this circumstance could be explained by a regression to the mean statistical effect. In our study, we adjusted all the results for the baseline BP values, thereby reducing the impact of this statistical effect.”
Further need for screening
“As a novel aspect of our study, the fact that the presence of severe OSA (apnea/hypopnea index 30 events per hour) was associated only with greater improvements in nocturnal BP ... and nocturnal BP pattern,” the researchers wrote. “Since both these parameters are closely associated with cardiovascular complications, this finding highlights still further the need to screen patients with resistant hypertension for OSA, as CPAP treatment can indeed provide cardiovascular protection.”
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