The Prevalence, Characteristics and Association of Obstructive Sleep Apnea with Blood Pressure Control in Patients with Resistant Hypertension
It has been observed that OSA is associated with resistant hypertension (RH), but there are surprisingly few studies on the characteristics of OSA in patients with RH. This multicenter, prospective cohort study by Sapina-Beltran et al. was recently published ahead of print in the Annals of ATS. The authors aimed to describe the prevalence of OSA in patients with RH, as well as assess for an association between blood pressure (BP) control and OSA.
The study included 284 patients ages 18-75 years old, with RH confirmed on 24-hour ambulatory blood pressure monitoring (ABPM). RH was defined as those with a BP above goal despite the use of three optimally dosed antihypertensive medications, or those requiring more than three antihypertensives including a diuretic. Additionally, hypertension could not be secondary to other causes. Uncontrolled RH was defined as an average 24-hour BP ≥130/80. All patients underwent sleep testing. Apnea-hypopnea index (AHI) (hypopneas scored by ≥4% desaturation or arousal) was used to group patients as non-OSA (AHI <5 events/hour), mild (AHI 5-14.9 events/hour), moderate (AHI 15-29.9 events/hour), or severe (AHI ≥30 events/hour) OSA. Patients on CPAP therapy were excluded. The study was conducted at centers in Spain, Brazil and Singapore.
Subjects included in the trial were mostly male (71.8%) and obese (median BMI 31.1 kg/m2) with a median age of 64 years old. The overall prevalence of OSA in this cohort with RH was 83.5%, 26.1% of whom had severe OSA. Those with severe OSA had an increased average 24-hour ABPM as compared to non-OSA subjects (adjusted mean difference 4.73 mmHg; 95% CI 0.71, 8.76). The largest difference was observed on average nighttime BP measurements (adjusted mean difference 5.72 mmHg; 95% CI 1.08, 10.35). The authors reported 2.7-fold odds of nocturnal hypertension with severe OSA as compared to the group without OSA (adjusted OR 2.7; 95%CI 1.15, 6.43). Furthermore, a statistically significant dose-response relationship was found between increasing average 24-hour ABPM and OSA severity (p value for trend = 0.014). Lastly, the authors found increased odds of severe OSA among participants with uncontrolled RH as compared to those with controlled RH though this association was not statistically significant (adjusted OR 1.69; 95% CI 0.97, 2.99).
This large multicenter international study adds to the existing evidence demonstrating high prevalence of comorbid RH and OSA. Though this study was cross-sectional, the dose-response relationship between increasing BP and OSA severity may suggest causality.
