ILLUSTRATIVE CASE
A 45-year-old woman with no chronic medical illness presents to your office for her annual physical examination. After a medical assistant (MA) applies an automatic BP cuff to the patient’s left arm, the BP reading is 155/92 mm Hg. The MA then rechecks the BP, and this time it reads 160/98 mm Hg. The MA performs a manual BP reading, which is 158/90 mm Hg (left arm) and 162/100 mm Hg (right arm). The patient denies any headache, visual changes, chest pain, or difficulty breathing and tells the MA that her BP is always high during a doctor visit. You are wondering if she has hypertension or if is this the white-coat effect.
Depending on the definition of hypertension, its prevalence among US adults 18 years or older varies from 46%, based on the American College of Cardiology guideline (≥ 130/80 mm Hg), to 29%, based on the Eighth Joint National Committee (JNC-8) guideline (≥ 140/90 mm Hg for adults ages 18–59 years and ≥ 150/90 mm Hg for adults ≥ 60 years without diabetes and/or chronic kidney disease).2,3
According to JNC-8, the prevalence is similar among men (30.2%) and women (27.7%) and increases with age: 18 to 39 years, 7.5%; 40 to 59 years, 33.2%; and ≥ 60 years, 63.1%.3,4 When ranked by risk-attributable disability-adjusted life-years (DALYs), high systolic blood pressure (SBP) is the leading risk factor, accounting for 10.4 million deaths and 218 million DALYs globally in 2017.5 National medical costs associated with hypertension are estimated to account for about $131 billion in annual health care expenditures, averaged over 12 years from 2003 to 2014.6
When performed correctly, the auscultatory method using a mercury sphygmomanometer correlates well with simultaneous intra-arterial BP and was considered the gold standard for office-based measurements for many years.7,8 However, significant observer-related differences in auditory acuity and terminal digit rounding are sources of inaccurate measurement. White-coat hypertension cannot be detected with this method—another significant limitation. The inaccuracy of office-based BP readings leads to concerns about hypertension being inappropriately diagnosed in patients or delays in diagnosis occurring.9
A proposed solution to this problem is measurement using an oscillometric sphygmomanometer. This device uses a pressure transducer to assess the oscillations of pressure in a cuff during gradual deflation; it provides accurate BP measurements when fully automated and programmed to complete several BP measurements at appropriate intervals while the patient rests alone in a quiet room.10
The accuracy of this new method was tested in a 2009 cohort study of 309 patients referred to an ambulatory blood pressure (ABP) monitoring unit at an academic hospital for diagnosis or management of hypertension.11 The study compared mean awake ABP, which continuously measures patients’ BP throughout the day, manual sphygmomanometer readings taken by the patient’s own physician, and an automated office blood pressure (AOBP) device called BpTRU (an automated oscillometric sphygmomanometer) while the patient rested alone in the exam room.11 The awake ABP is a federally approved standard for the diagnosis of white-coat hypertension.12 In this study, the white-coat response was negated with the use of the automated BpTRU device.11
A 2019 meta-analysis that included 26 studies (N = 7116) comparing AOBP with other BP measurement techniques concluded that the use of automated oscillometric BP readings is more accurate for diagnosing hypertension and assists in negating the white-coat hypertension effect.9
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