Patients who have high blood pressure that is resistant to treatment as well as obstructive sleep apnea (OSA) face a significant complication, as the more severe their OSA, the higher their blood pressure, according to researchers at the Hospital Universitari Arnau de Vilanova in Lleida, Spain.
The study examined 284 patients between the ages of 18 and 75 who were treated at hospitals in Spain, Singapore, and Brazil for resistant hypertension (RH). Of all patients with high blood pressure, those with RH, which requires three or more drugs to control, are at greatest risk for a heart attack or other cardiovascular event.
“We believe that OSA plays an important role in the pathogenesis and prognosis of patients with resistant hypertension,” said senior author Mireia Dalmases Cleries, MD, a pulmonologist and sleep researcher at the hospital. “Our study shows a dose-response association between OSA severity and blood pressure, especially during the nighttime period.”
According to the study:
- 83.5% of patients with RH had OSA, including 31.7% with mild OSA, 25.7% with moderate OSA, and 31.5% with severe OSA
- OSA was slightly more likely in men than women, 86.3% versus 76%, though men were twice as likely to have severe OSA
- As the severity of OSA increased, ambulatory blood pressure increased, particularly at night, with average nighttime ambulatory blood pressure 5.72 mmHg higher in those with severe OSA compared to those without OSA
High blood pressure at night is a stronger predictor of cardiovascular risk than those whose blood pressure is high during the day, the researchers report. The study was not a randomized, controlled trial, though, so the authors say that it cannot prove cause and effect. Also, only patients with RH were included, so the study’s findings cannot be generalized to other patients with high blood pressure.
These findings were derived from an ancillary study of the SARAH project, which is evaluating the impact of OSA and continuous positive airway pressure (CPAP) on cardiovascular outcomes over five years of follow-up in what the researchers expect to be the largest group of participants with RH and a sleep assessment.
Even before the results of SARAH are known, Dalmases Cleries said that “considering the high prevalence of OSA in resistant hypertensive subjects and findings from previous studies which show that treating OSA with CPAP can lower blood pressure, clinicians should consider performing a sleep study in patients with resistant hypertension.”
The study, “Prevalence, Characteristics, and Association of Obstructive Sleep Apnea With Blood Pressure Control in Patients With Resistant Hypertension,” was published by the Annals of the American Thoracic Society.