More Precise and Unbiased Blood Pressure Measures: Automatic Office Blood Pressure

Elevated blood pressure (BP) is an important and modifiable risk factor for stroke and coronary heart disease. The risk assessment for cardiovascular disease and treatment of hypertension is largely based on solitary brachial cuff BP reading obtained in clinical settings. Currently, ambulatory BP monitor (ABPM) remains the golden standard of hypertension diagnosis and treatment. However, the ABPM measure is not only costly and is not widely available in some countries, especially in the USA1 because it is poorly reimbursed by third-party payers. In this issue, the brief report by Juraschek et al.2 provides us with more evidence for a more cost-effective method to measure BP, the unattended automatic office BP (AOBP). They conducted a 3-day investigation to compare the BP levels and hypertension prevalence by exploiting 24-hour ABPM, 2 manual clinic-based BP measurements (over 2 visits), and an AOBP measurement (single visit). In their report, the BP levels and hypertension prevalence evaluated with AOBP were comparable to that measured with wake-time 24-hour ABPM.2 With reference to daytime ABPM readings, the performance of 2 manual clinical-based BP was more imprecise and biased. The average of 2 manual BPs was significantly higher than wake-time ABPM with mean difference of 5.5 mm Hg (P < 0.001) for systolic BP and 2.7 mm Hg (P = 0.002) for diastolic BP and had a significantly higher hypertension prevalence (systolic BP ≥ 140 mm Hg or diastolic BP ≥ 90 mm Hg) (49.5% vs. 27.2% for ABPM, P < 0.001). However, the AOBP measurements did not differ from ABPM (mean difference 1.6 mm Hg for systolic BP (P = 0.21) and −0.5 mm Hg for diastolic BP (P = 0.62)) and had similar hypertension prevalence to ABPM (31.1% vs. 27.2% for ABPM, P = 0.57). Studies have been supporting that the AOBP, without the attendance of a health professional for measurement, could avoid white coat effect.3 However, studies suggested that there was only a small difference between attended and unattended office BP measurements either at baseline or during follow-up4; yet, other studies have suggested the human presence (attended) has a substantive impact on the obtained BP measurement.5 In fact, the white coat effect may be caused by the poor adherence to the standard BP measurement protocol rather than by the patient’s interaction with a health care professional wearing a white coat. In other words, the rigorous implementation of a standard BP measurement protocol may reduce the observed white coat effect. More studies are required to address this issue. A systematic review and meta-analysis has also suggested that, for subjects with suspected hypertension, AOBP measurement should replace the BP recordings by nurses and physicians in routine clinical practice.3 Besides, Boonyasai et al. also addressed that some barriers for the implementation of AOBP in primary care may result from knowledge, attitudes, and external factors.6 Training the medical personnel to correctly use AOBP is one of the imperative approaches to conquer these corresponding barriers. The implementation of AOBP with a standard BP measurement protocol (5-minute rest, seated position with appropriate-size cuff on their bare arm, arm at heart level, back supported, legs uncrossed, and feet not dangling) is essential to obtain more precise BP measurements. In other words, the AOBP device with standard protocol obtains the average from multiple BP readings is substantively more accurate than office BP. For the barriers relating to attitude, providing more scientific evidences to clinic practices, which AOBP reduces the misclassification of hypertension, may help motivate them to implement the standard AOBP measurement protocol.6 Nonetheless, the standard process of AOBP measurements is time costed and the clinical managers and personnel may have resistance to accept the change of practice. For these external barriers, the integration of the standard AOBP protocol into the routine clinical workflow can be started by improving the office environment for an easier implementation of AOBP.6 Furthermore, Moore et al. compared AOBP against 24-hour ABPM and found that averaging the results of 2 of 3 BP readings yielded optimal results.7 In the report by Juraschek et al., averaged AOBP of second and third had the least difference from the wake-time ABPM. These results suggested that the improvement in AOBP accuracy could be possibly achieved by discarding the first measurement of the AOBP. The body of evidence including this study by Juraschek et al.2 supports the use of AOBP in primary care, which can improve the accuracy of clinical BP measurement against wake-time ABPM. The author declared no conflict of interest.