FROM ANNALS OF INTERNAL MEDICINE
Physicians should use ambulatory blood pressure screening to confirm elevated office measurements before diagnosing hypertension, according to a draft recommendation from the U.S. Preventive Services Task Force.
Because high blood pressure affects nearly a third of U.S. adults, the USPSTF recommends screening all adults for high blood pressure, based on good evidence that screening and treatment reduce cardiovascular events with few major harms.
However, blood pressure fluctuates with emotion, stress, pain, physical activity, medications, and even the presence of health care providers. So, the USPSTF issued a draft, A-level recommendation to use ambulatory or home blood pressure monitoring following an initial elevated screening to confirm a diagnosis of hypertension, except when initiating therapy immediately is medically necessary.
Patients with blood pressure at or above 180/110 mm Hg or evidence of end-organ damage should begin drug therapy immediately. In addition, patients diagnosed with secondary hypertension do not need ambulatory monitoring confirmation.
The USPSTF recommendations are based on a meta-analysis published Dec. 22 (Ann. Intern. Med. 2014: [ doi10.7326/M14-1539 ]. Although the evidence for ambulatory screening confirmation was of good quality, the evidence base is less robust for home monitoring, the task force noted.
“Our evidence review shows that overdiagnosis of hypertension from unconfirmed office-based screening could result in unnecessary treatment in a substantial number of persons,” reported Margaret A. Piper, Ph.D., of Kaiser Permanente Center for Health Research, Portland, Ore., and her associates in the study. “Ambulatory BP monitoring provides multiple measurements over time in a nonmedical setting, which potentially avoids measurement error, regression to the mean, and misdiagnosis of isolated clinic hypertension, and is best correlated with long-term outcomes.”
Dr. Piper’s team searched for good- and fair-quality studies in MEDLINE, PubMed, the Cochrane Central Register of Controlled Trials and CINAHL through August 2014, yielding 1 trial for the benefits of screening, 7 studies on the diagnostic accuracy of office blood pressure measurement, 11 studies on the diagnostic accuracy of ambulatory blood pressure measurement, 27 studies on using ambulatory screenings to confirm hypertension, 4 studies on harms of screening, and 40 studies on rescreening intervals and hypertension incidence in those with normal blood pressure.
The meta-analysis showed that 5%-65% of patients were not diagnosed with hypertension following ambulatory blood pressure monitoring after an initially elevated office screening measurement.
The USPSTF draft recommendation also noted past epidemiological evidence that 15%-30% of those diagnosed with hypertension may actually have lower blood pressure when not in a medical setting.
The meta-analysis also found that the risk of fatal and nonfatal stroke and cardiovascular events was “consistently and significantly associated with” elevated systolic ambulatory blood pressure, regardless of the measurements in an office.
The primary harms of screening identified in the study were greater absenteeism from work and greater illness episodes after diagnosis, as well as sleep disturbances, discomfort, and daily activity restrictions because of the ambulatory device.
On the basis of the evidence from the meta-analysis, the USPSTF recommended annual screenings for adults age 40 years and older and those at high risk for hypertension, including African Americans, those who are overweight or obese, and those with a normally high blood pressure (130-139/85-89 mm Hg). Screenings should occur every 3-5 years for those age 18-39 years with no risk factors and a normal blood pressure.
Target blood pressure should remain below 140/90 mm Hg for adults younger than 60 years, and below 150/90 mm Hg for adults 60 years or older with neither diabetes nor chronic kidney disease, according to guidelines from the Eighth Joint National Committee on Prevention, Detection, Evaluation and Treatment of High Blood Pressure.
The U.S. Agency for Healthcare Research and Quality funded the meta-analysis. The authors had no relevant disclosures.