Most patients with resistant hypertension have obstructive sleep apnoea (OSA) and the degree of hypertension is greater with more severe OSA, research has shown. Authors of the study,* published today in the Annals of the American Thoracic Society, said doctors should consider performing a sleep study in people with resistant hypertension after they found that almost a third of people with resistant hypertension had severe OSA.
As an ancillary study of the SARAH project – which is evaluating the impact of OSA and continuous positive airway pressure (CPAP), the gold standard for OSA treatment, on cardiovascular outcomes over five years’ follow-up – the team studied 284 men and women aged 18-75 years who were being treated for resistant hypertension in hospitals in Spain, Singapore and Brazil. They reported that:
- 83.5% of patients with resistant hypertension 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 in women: 86.3% vs. 76%; but men were twice as likely as women to have severe OSA.
- As the severity of OSA increased, ambulatory blood pressure increased, particularly at night. The average night-time ambulatory blood pressure was 5.72mmHg higher in people with severe OSA compared with those without OSA.
The study authors pointed out that people with resistant hypertension – which requires at least three different drugs to control – are at the greatest risk for myocardial infarction or other cardiovascular event among all patients with hypertension. And they pointed out that compared with daytime hypertension, night-time hypertension is a stronger predictor of cardiovascular risk.
They said that because their study is not a randomised, controlled trial it cannot prove cause and effect; and because only patients with resistant hypertension were included in the study, their findings cannot be generalised to other patients with high blood pressure.
They commented: “We believe that OSA plays an important role in the pathogenesis and prognosis of patients with resistant hypertension. Our study shows a dose-response association between OSA severity and blood pressure, especially during the night-time period.”
Ans they recommended: “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.”
* Sapiña-Beltrán E, Torres G, Benitez I, et al. Prevalence, characteristics and association of obstructive sleep apnea with blood pressure control in patients with resistant hypertension. Annals of the American Thoracic Society, published online 13 September 2019.