Compared with office-based BP measurements, ABPM has a stronger positive correlation with clinical CVD outcomes and HTN-related organ damage.1 ABPM has the advantage of being able to provide a large number of measurements over the course of a patient’s daily activities, including sleep. It is useful to evaluate for a wide spectrum of hypertensive or hypotensive patterns, including nocturnal, postprandial, and drug-related patterns. ABPM also is used to assess for white-coat HTN and masked HTN.1
Among these BP phenotypes, an estimated 15% to 30% of adults in the United States exhibit white-coat HTN.1 Most evidence suggests that white-coat HTN confers similar cardiovascular risk as normotension, and it therefore does not require treatment.35 Confirming this diagnosis saves the individual and the health care system the cost of unnecessary diagnosis and treatment.
A home monitor that assesses sleep BP is available in some US markets, with data showing its sleep measurements are similar to those obtained with ambulatory BP monitoring.
One cost-effectiveness study using ABPM for annual screening with subsequent treatment for those confirmed to be hypertensive found that ABPM reduced treatment-years by correctly identifying white-coat HTN, and also delayed treatment for those who would eventually develop HTN with advancing age.36 The estimates in savings were 3% to 14% for total cost of care for hypertension and 10% to 23% reduction in treatment days.36 An Australian study showed similar cost reductions.37 A more recent analysis demonstrated that compared with clinic BP measurement alone, incorporation of ABPM is associated with lifetime cost-savings ranging from $77 to $5013, depending on the age and sex of the patients modeled.38
ABPM can also be used to rule out white-coat effect in patients being evaluated for resistant HTN. Several studies demonstrate that among patients with apparent resistant HTN, approximately one-third have controlled BP when assessed by ABPM.39-41 Thus, it is recommended to conduct an out-of-office BP assessment in patients with apparent resistant HTN prior to adding another medication.41Twelve percent of US adults have masked HTN.42 As described earlier, these patients, unrecognized without out-of-office BP assessment, are twice as likely to experience a CVD event compared with normotensive patients.1,42,43
ABPM nuts and bolts
ABPM devices are typically worn for 24 hours and with little interruption to daily routines. Prior to BP capture, the device will alert the patient to ensure the patient’s arm can be held still while the BP measurement is being captured.44 At the completion of 24 hours, specific software uses the stored data to calculate the BP and heart rate averages, as well as minimums and maximums throughout the monitoring period. Clinical decision-making should be driven by the average BP measurements during times of sleep and wakefulness.1,14,44FIGURE 3 is an example of output from an ABPM session. TABLE 31,44 offers a comparison of HBPM and ABPM.
Limitations of ABPM
While ABPM has been designed to be almost effortless to use, some may find it inconvenient to wear. The repeated cuff inflations can cause discomfort or bruising, and the device can interfere with sleep.45 Inconsistent or incorrect wear of ABPM can diminish the quality of BP measurements, which can potentially affect interpretation and subsequent clinical decision-making. Therefore, consider the likelihood of correct and complete usage before ordering ABPM for your patient. Such deliberation is particularly relevant when there is concern for BP phenotypes such as nocturnal nondipping (failure of BP to fall appropriately during sleep) and postprandial HTN and hypotension.
Conduct out-of-office BP assessment of apparent resistant hypertension before adding another medication.
Trained personnel are needed to oversee coordination of the ABPM service within the clinic and to educate patients about proper wear. Additionally, ABPM has not been widely used in US clinical practices to date, in part because this diagnostic strategy is not favorably reimbursed. Based on geographic region, Medicare currently pays between $56 and $122 per 24-hour ABPM session, and only for suspected white-coat HTN.38Discrepancies remain between commercial and Medicaid/Medicare coverage.44
