SAN FRANCISCO– A 24-week program combining weight-loss efforts with continuous positive airway pressure produced significantly greater reductions in systolic blood pressure in obese patients with obstructive sleep apnea, compared with either intervention alone, a study of 181 adults found.
In an intent-to-treat analysis, all three groups reduced systolic pressures to a statistically similar extent, compared with baseline – decreases of approximately 8 mm Hg in the combination group and 4 mm Hg with either monotherapy. Among 136 patients who adhered to therapy by completing the trial, however, systolic blood pressure decreased by a mean of 14 mm Hg in the 62 patients randomized to the combination of weight-loss efforts and continuous positive airway pressure (CPAP), a significantly greater decrease than the reductions of approximately 7 mm Hg in 61 patients randomized to weight-loss efforts alone and 3 mm Hg in 58 patients who got CPAP alone.
Dr. Julio A. Chirinos
A 14 mm Hg–drop in systolic blood pressure is an "important reduction" with potentially significant clinical benefits in obese patients with obstructive sleep apnea, Dr. Julio A. Chirinos said at the annual meeting of the American College of Cardiology.
Previous observational studies have shown strong associations in obesity, obstructive sleep apnea, and hypertension but have not been able to assess whether there is any incremental blood pressure benefit to combining treatments for obesity and sleep apnea.
Dr. Chirinos and his associates conducted an ancillary analysis of data from the Cardiovascular Consequences of Obstructive Sleep Apnea trial, which focused primarily on the treatments’ effects on C-reactive protein levels. The study randomized adults with at least moderate obesity and moderate to severe obstructive sleep apnea and C-reactive protein levels greater than 1 mg/L to the three intervention groups. Baseline characteristics were similar among groups. Approximately 41% of patients were hypertensive at baseline.
In the per-protocol analysis of patients who adhered to therapy, the decreases in systolic blood pressure, compared with baseline, were statistically significant in the combination and weight-loss groups but not the CPAP group, reported Dr. Chirinos of the University of Pennsylvania, Philadelphia.
Body weight and body mass index decreased significantly in the weight-loss and combination groups compared with baseline but did not change significantly in the CPAP group. Patients in the weight-loss and combination groups dropped approximately 7 kg in the intent-to-treat analysis and 10-11 kg in the per-protocol analysis. Body mass index decreased by a mean of two to three points in the intent-to-treat analysis and by approximately four points among those who adhered to therapy. No details were provided about the specifics of the weight-loss efforts.
Mean arterial pressure decreased significantly in all three groups, compared with baseline, in both intent-to-treat and per-protocol analyses, but fell significantly more in the combination group, compared with monotherapy, in the per-protocol analysis. Among patients adherent to treatment, mean arterial pressure decreased by more than 10 mm Hg in the combination group, compared with approximately 4 mm Hg–declines with either monotherapy.
Only combination therapy significantly reduced brachial pulse pressure, compared with baseline (by approximately 3 mm Hg), in the intent-to-treat analysis. In the per-protocol analysis, brachial pulse pressure dropped significantly, compared with baseline, in the combination group (a 6 mm Hg decrease) and the weight-loss group (a 4 mm Hg–decrease) but not in the CPAP group.
Brachial pulse pressure decreased significantly with combination therapy in the intent-to-treat analysis but not with either treatment alone. Mean brachial pulse pressure in the per-protocol analysis decreased significantly with combination therapy (a 6 mm Hg–reduction) or weight-loss therapy (a 4 mm Hg–decrease) but increased in the CPAP group.
Carotid-radial pulse pressure amplification measurements did not change significantly from baseline in any group, suggesting that the study’s results were not brought about by missing some changes in central pressure that were not being picked up by brachial measurements, Dr. Chirinos said.
In general, approximately 50% of people with obstructive sleep apnea have hypertension, and around 30% of hypertensive patients have obstructive sleep apnea, he said.
The findings are limited by the study’s strict criteria for patient inclusion or exclusion, its lack of arterial blood pressure monitoring, the use of noninvasive estimates of central pressure measurements, and its duration of only 6 months. The study used carotid tonometry to measure central pulse pressure.
The study excluded patients with blood pressures greater than 160/95 mm Hg, those with predominantly central sleep apnea, patients using supplemental oxygen, and anyone in a high-risk occupation or with a record of dangerous driving. Also excluded were patients with confounders of systemic inflammation, sustained arrhythmia, unstable cardiopulmonary disease, severe restless leg syndrome or chronic pain causing frequent night awakenings, pregnancy, severe depression or other serious medical or psychological conditions that might compromise their safety in the study, and prior CPAP within 8 weeks of the study.