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USPSTF: Ambulatory BP should be used to confirm elevated office BP
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Current evidence supports the use of ambulatory BP monitoring as the reference standard for confirming elevated office BP screening results, according to a review conducted for the US Preventive Services Task Force.
The review also concluded that people with BP in the high-normal range, older people, those with above-normal BMI and black adults are at greater risk for hypertension upon re-screening within 6 years compared with other populations.
The reviewers for the US Preventive Services Task Force (USPSTF) examined direct evidence of the benefits and harms for BP screening, diagnostic accuracy of office BP measurement, prediction of CV events by BP method and diagnostic accuracy of nonoffice measurement, and re-screening interval.
Margaret A. Piper, PhD, MPH, from Kaiser Permanente Center for Health Research, Portland, Ore., and colleagues found one trial that concluded that BP screening was associated with fewer annual composite CV-related hospitalizations (rate ratio=0.91; 95% CI, 0.86-0.97).
The group found four studies that examined whether automated oscillometric office BP measurement predicted results in reference to manual sphygmomanometry. Three studies that defined elevated BP as systolic BP ≥140 mm Hg or diastolic BP ≥90 mm Hg reported sensitivities of 51% to 68% for automated oscillometric office BP measurement; one study defining elevated BP as systolic BP ≥160 mm Hg or diastolic BP ≥95 mm Hg reported a 91% sensitivity.
Ambulatory BP monitoring predicted events
Piper and colleagues reviewed 11 studies to evaluate the predictive value of ambulatory BP monitoring for long-term CV events after adjustment for office BP measurement. They found that each 10-mm Hg increment in 24-hour systolic ambulatory BP was consistently and significantly associated with increased risk for fatal and nonfatal stroke in four studies, with HRs ranging from 1.28 to 1.4, and for increased risk for fatal and nonfatal CV events in five studies, with HRs ranging from 1.11 to 1.42. One study reported a nonsignificant increased risk for fatal and nonfatal CV events, and one reported that ambulatory BP measurement predicted CV mortality in a model that included office BP measurement (P<.001).
The reviewers did not find any differences in HRs by different ambulatory BP monitoring protocols.
Five studies that evaluated the predictive value of home BP monitoring yielded significant associations with increased risk for CV and mortality outcomes, with HRs ranging from 1.17 to 1.39, according to the reviewers.
Across 24 studies, the percentage of patients with an elevated BP at screening who were hypertensive on confirmatory testing by ambulatory BP monitoring or home BP monitoring ranged from 35% to 95%, Piper and colleagues wrote.
When the reviewers examined harms of screening for high BP, four studies reported no effect on quality of life or psychological distress among those who were hypertensive or prehypertensive; four studies reported sleep disturbances, discomfort and restrictions in daily activities when using an ambulatory BP monitoring device; and one study reported that those previously unaware of their hypertension status had increased absenteeism and illness after diagnosis.
Hypertension incidence varied
Forty studies of hypertension incidence after re-screening had wide estimates of incidence at each re-screening interval, ranging from 2.2% to 4.4% at 1 year to 2.1% to 28.4% at 5 years, Piper and colleagues wrote.
The incidence of hypertension was higher with increasing age, increasing baseline BP and increasing weight. It was also greater for men compared with women and for black adults compared with other races and ethnicities. The report documented no difference in hypertension incidence based on smoking status.
“Initially elevated BP measured by office-based methods is best confirmed by [ambulatory BP monitoring] to avoid potential overdiagnosis of isolated clinic hypertension and the potential harms of unnecessary treatment,” Piper and colleagues wrote. “Time and resources might be better directed toward improved measurement accuracy and timely measurement in higher-risk persons rather than measurement of all persons at every office visit.”
Disclosure: The reviewers report receiving grants from the Agency for Healthcare Research and Quality and the National Heart, Lung and Blood Institute.
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