From the Journals

Untreated OSA linked to resistant hypertension in black patients



Untreated moderate or severe obstructive sleep apnea (OSA) was associated with greater odds of resistant hypertension in black patients, according to findings published in Circulation.

In an analysis of 664 patients with hypertension, those with moderate to severe OSA had twofold higher odds of resistant hypertension, compared with those with no or mild OSA (odds ratio, 2.04; 95% confidence interval, 1.14-3.67), reported Dayna A. Johnson, PhD, of the Division of Sleep and Circadian Disorders at Brigham and Women’s Hospital, Boston, and coauthors.

Participants were enrolled in the JHSS, an ancillary trial conducted during December 2012 – May 2016 as part of the Jackson Heart Study, a longitudinal study of 5,306 black adults aged 21-95 years in Jackson, Miss. Patients included in the analysis had hypertension (defined as high blood pressure, use of antihypertensive medication, or self-reported diagnosis). Those without a valid in-home sleep apnea test and with missing data on hypertension, measured blood pressure, or use of antihypertensive medications and diuretics were excluded from analysis.

Sleep apnea was assessed using measures of nasal pressure, thoracic and abdominal inductance plethysmography, finger pulse oximetry, body position, and electrocardiography with a validated Type 3 home sleep apnea device. Obstructive apneas were identified as a flat or nearly flat amplitude of the nasal pressure signal for greater than 10 seconds, accompanied by respiratory effort on the abdominal or thoracic inductance plethysmography bands. Severity was defined by the standard Respiratory Event Index (REI) categories: fewer than 5 events (unaffected), greater than or equal to 5 events to fewer than 15 events (mild), greater than or equal to 15 events to fewer than 30 events (moderate), and greater than or equal to 30 events (severe), the authors reported.

High blood pressure (BP) was defined as systolic BP greater than or equal to 130 mm Hg or diastolic BP greater than or equal to 80 mm Hg. Controlled hypertension was defined as systolic BP less than 130 mmHg and diastolic BP less than 80 mm Hg.

Uncontrolled BP was defined as high BP with use of one or two classes of antihypertensive medications; resistant hypertension was defined as having high BP while on greater than or equal to three classes of antihypertensive medications with one being a diuretic or as using of greater than four classes of antihypertensive medications regardless of BP control, Dr. Johnson and colleagues reported.

A total of 25.7% of hypertension patients had moderate or severe OSA, though only 6% of these patients had an OSA diagnosis from a physician. In addition, 48.2% of patients had uncontrolled hypertension, and 14.5% had resistant hypertension.

Moderate or severe OSA was associated with nearly twofold higher unadjusted odds of resistant hypertension (OR, 1.92; 95% CI, 1.15-3.20). In adjusted models, moderate or severe OSA and nocturnal hypoxemia were not associated with uncontrolled hypertension but were associated with resistant hypertension (OR, 2.04; 95% CI, 1.14-3.67; OR, 1.25; 95% CI, 1.01-1.55, respectively).

Compared with no OSA, severe OSA was associated with more than three times higher odds of resistant hypertension (OR, 3.50; 95% CI, 1.54-7.91). This association was even higher after adjustment for covariates (OR, 3.58; 95% CI, 1.39-9.19).

“These data suggest that untreated OSA may contribute to the high burden of resistant hypertension in blacks,” Dr. Johnson and coauthors wrote. “Future studies should test whether diagnosis and treatment of OSA may be interventions for improving BP control” and reducing this burden, they added.

“These findings are particularly important given that most adults with OSA are undiagnosed and untreated.”

The study was funded by grants from the National Heart, Lung, and Blood Institute. One of the authors reported receiving funding from Amgen. No other disclosures were reported.

SOURCE: Johnson D et al. Circulation. 2018. doi: 10.1161/CIRCULATIONAHA.118.036675.

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