Should All Patients Have Ambulatory Blood Pressure Monitoring Performed to Validate the Diagnosis of Hypertension?

Hypertension affects approximately 30% of the US adult population, making it the most common condition diagnosed during outpatient office visits. Hypertension is a major risk factor for cardiovascular disease, stroke, and chronic kidney disease. The United States Preventive Services Task Force (USPSTF) has a draft recommending the use of ambulatory blood pressure (BP) monitoring (ABPM) in adults to confirm the diagnosis of hypertension except in cases where immediate initiation of therapy is required.1 This recommendation is based on a systematic review by Piper and colleagues2 that was performed for the USPSTF to assess the benefits and harms of screening for hypertension in adults and to summarize the evidence on rescreening intervals and diagnostic and predictive accuracy of different BP methods for cardiovascular events. The main findings of the systematic review include the following: (1) there is good evidence that screening for and treatment of hypertension in adults substantially decreases the incidence of cardiovascular events and is not harmful, and the net benefit of screening is substantial; (2) neither manual nor automated measurement of office BP was superior to the other; (3) 15% to 30% of patients thought to have hypertension may have lower BP outside of the office setting and disadvantages for diagnosing hypertension only in the office setting include measurement errors, the limited number of measurements that it is convenient to make in the office, and increased risk of isolated systolic hypertension/white‐coat hypertension; (4) studies vary but 5% to 65% of patients with elevated office BP were not diagnosed with hypertension after they had ABPM performed; (5) increased systolic BP as measured by ambulatory monitoring was significantly associated with increased risk for fatal and nonfatal stroke and cardiovascular events independent of the office BP measurements; (6) in patients who had isolated clinic hypertension/white‐coat hypertension and normotension confirmed on ABPM, cardiovascular outcomes were similar to those who were normotensive at screening; and (7) patients with high‐normal BP (130–139/85–89 mm Hg), those were overweight or obese, and African Americans had a two‐fold increased incidence of hypertension on rescreening within 6 years than those without these risk factors.

Based on these findings, the preliminary draft of the USPSTF1 recommends that ABPM be the reference standard used to confirm the diagnosis of hypertension in all adults aside from those with secondary causes of hypertension and those in whom immediate initiation of drug therapy is indicated (those with BP >180/110 mm Hg or evidence of target organ damage). They also recommend annual screening for adults 40 years and older and those at increased risk for high BP, which includes those with high‐normal BP (130–139/85–89 mm Hg), those who are overweight or obese, and African Americans. Adults aged 18 to 39 years with normal BP (<130/85 mm Hg) and no other risk factors should be rescreened every 3 to 5 years. If BP is elevated at rescreening, the diagnosis should be confirmed with ABPM.

The rationale behind using ABPM to confirm the diagnosis of hypertension is to avoid misdiagnosing and overtreatment of patients with white‐coat hypertension. The Canadian Hypertension Education Program has recommended using ABPM to diagnose hypertension since 2005.3 The National Institute for Health and Care Excellence (NICE) guidelines in the United Kingdom recommend that if office BP is 140/90 mm Hg or higher, ABPM should be performed to confirm the diagnosis of hypertension.4 They stated that this strategy would improve the accuracy of the diagnosis and would be cost‐effective, prevent treatment of patients with white‐coat hypertension, and result in cost savings for the National Health System. There are no current data available yet to assess the impact of implementing these guidelines.

There are major issues implementing this recommendation in the United States. Firstly, ambulatory BP devices are costly (approximately $2500) and are not currently widely available. Performing ABPM is poorly reimbursed frequently in the range of $50 to $100 and only for the indication of white‐coat hypertension. The current reimbursement is inadequate to offset the costs of personnel and supplies to perform and the time spent to review and interpret the ABPM study. If this recommendation is implemented, this would force insurers to re‐evaluate the reimbursement of this procedure but would not automatically guarantee payment.

Another option is to consider the use of fully automated office BP (AOBP) measurements. There are a number of devices available that provide fully automated oscillometric sphygmomanometers designed for professional use that are capable of taking multiple BP readings with the patient resting alone in a quiet room or sequestered in a quiet location in the waiting room area.5 These devices typically discard the first reading and then take three to five automated readings with 1‐minute intervals. This methodology maintains the role of office BP readings in the diagnosis and management of hypertension but allows an automated measurement with the patient resting quietly alone. A review of the studies evaluating AOBP indicates that it provides BP values that correlate well with daytime ABPM and home BP readings. AOBP also appears to correlate well with target organ damage.6

The recommendation by the USPSTF is still in draft form and subject to revision. It has focused attention on the issues of BP measurement in the office setting and it appears that we could be doing a better job at diagnosing hypertension correctly, avoiding excessive costs from testing and medication when little benefit is to be expected to be derived in patients with white‐coat hypertension. However, it is important to recall that patients with white‐coat hypertension are at increased risk for becoming hypertensive in the future and do require long‐term follow‐up.