The optimal use of automated office blood pressure measurement in clinical practice

Abstract

This evidence‐based article endorses the use of automated office blood pressure (AOBP). AOBP is the most favorable office blood pressure (BP) measuring technique as it provides accurate readings with 3‐15 mm Hg lower values than the casual conventional office measurements with auscultatory or semi‐automated oscillometric devices and relates closely to awake ABP readings. The AOBP technique seems to be superior to conventional office BP in predicting hypertension‐mediated organ damage and appears to be equally reliable to awake ABP in the prediction of cardiovascular (CV) disease. AOBP readings should be obtained either unattended, with the patient alone in the examination room, or attended with the presence of personnel in the room but with no talking to the patient, although this recommendation is not frequently followed in routine clinical practice. To optimize office BP readings, the type of device, the rest period before AOBP measurements (preceding rest), and the time intervals between measurements were evaluated. As AOBP readings have the advantage of removing many confounding factors, the authors propose to perform measurements with a preceding rest in all patients at the initial visit; if AOBP readings remain <130 mm Hg in subsequent visits, measurements could be accepted, otherwise, if are higher, patients should be evaluated by out‐of‐office BP measurements.

1. INTRODUCTION

Office blood pressure (BP) measurements have a central role in screening for the presence of hypertension. Nonetheless, conventional office BP readings by an auscultatory or oscillometric device may lead to misclassification of BP and inappropriate treatment. During the previous decades, automated office BP (AOBP) technique has been developed.1 This technique uses a fully automated oscillometric device that records multiple BP readings with the patient resting in the examination room. The device does not require activation by the patient, thus allaying patient anxiety. Furthermore, as patient is being left alone in the examination room or separated from others in a waiting area and not near to office staff, AOBP technique has been shown to reduce or eliminate the “white coat effect.” Thus, AOBP produces values up to 3‐15 mm Hg lower than those obtained from casual conventional office BP measurements without waiting time, which are closely related to those provided by awake ambulatory blood pressure (ABP).2, 3 Multiple causes of inaccurate BP measurement in clinical practice exist and could be attributed to the conventional office BP measurement methods. These are categorized into patient‐related, procedure‐related, equipment‐related, or more common observer‐related.4 The validity of AOBP against the other conventional methods is further supported by the CAMBO trial (Conventional Versus Automated Measurement of BP in the Office) where AOBP was compared with auscultatory office BP in routine clinical practice in hypertensive subjects in 5 cities in eastern Canada. Its results revealed that, at the first office visit, the difference in systolic BP values between AOBP and awake ABP was smaller compared with the systolic BP values between auscultatory office and the mean awake ABP by 2.3 mm Hg and 6.5 mm Hg, for AOBP and auscultatory technique, respectively.5 Meanwhile when conventional clinic measurements, using oscillometric or auscultatory technique, were taken carefully following a standardized BP measurement procedure, similar BP values were recorded.6 Moreover, it has been shown that the unattended AOBP readings have a stronger association with subclinical CV disease and organ damage, including left ventricular hypertrophy.7 It has been recently shown that attended or unattended AOBP is equally correlated to left ventricular mass as well as carotid artery intima‐media thickness and plaque formation.8 The AOBP technique is also a more reliable modality than manual office for determining BP in patients with chronic kidney disease (CKD)9 and seems to correlate closer to awake ABP in hypertensive subjects with microalbuminuria.10 Considering the current shift away from manual BP measurement and the recommendation to obtain multiple BP readings at a single visit, the new AHA statement suggests that AOBP may be preferred for use in clinical practice.11 AOBP has also been recognized by the 2018 ESC/ESH Guidelines as the technique that improves the reproducibility of BP measurement in the doctor's office.12 In addition, the AOBP technique seems to be a superior office BP measurement method by the position statement of the European Society of Hypertension working group on BP monitoring and variability, but deserves further investigation.13 This method is also recommended by the Canadian Hypertension Education Program as the preferable technique for office BP measurement.14 The Systolic Blood Pressure Intervention Trial (SPRINT), which involved a high‐risk population with a clinic systolic BP ≥130 mm Hg without diabetes mellitus or history of stroke, used AOBP to measure BP.15 The critics in the study questioned whether the results could be applied to clinical practice.16 However, it has been suggested that SPRINT’s BP measurement protocol adheres to traditional research methods more closely than techniques used in real‐world settings.17 Despite the superiority of AOBP against the more traditional methods of recording BP during an office visit, physicians are reluctant to adopt this technique because of the uncertainty about its advantages.18 The aim of the present opinion article is to optimize the use of AOBP in clinical practice providing the necessary evidence to support this view.

2. FACTORS THAT INFLUENCE AOBP MEASUREMENTS ARE THE FOLLOWING

2.1. Device type

Available fully automated devices are listed at http://www.dableducational.org/ and in the British and Irish Hypertension Society (https://bihsoc.org/bpmonitors/) (ie, BpTRU, Microlife WatchBP Office, Omron HEM 907, Omron HEM 705CP).19 Other BP devices that have been used to perform automated measurements in published studies are the following:

1. the BP monitor CB‐1805‐B Biox20

2. the Dinamap pro‐Care6

3. the Omron M10IT21

4. the Task Force Monitor CNS (this monitor performs beat‐to‐beat BP monitoring but it has also been used to perform automated measurements).22

5. the Omron 9000Ai,23 and

6. the Omron HEM 7080 IC.24

After the abrogation of the BpTRU devices manufacture, the most commonly used fully automated BP monitors are the Omron HEM 907 and the Microlife WatchBP office, both of which have been repeatedly validated in many studies.25, 26, 27, 28

The Omron HEM 907 device, used in the SPRINT, provides single, double, or three measurements before displaying the average, after 0, 3, 5, or 10 minutes of rest. Similarly, the Microlife WatchBP Office gives the opportunity to select the time‐period of rest before measurements and the possibility to obtain BP measurement in one arm or in both arms simultaneously, by using two upper arm cuffs.29 Neither of the two aforementioned devices discards the first BP reading, in contrast to the abrogated BpTRU which yielded a total of six readings. The Omron HEM 907 is not recommended in end‐stage renal disease before and after hemodialysis, and it has been specifically validated for use in the elderly without atrial fibrillation or frequent ectopic beats.30 The Microlife Watch BP Office has been shown to predict equal to awake ABP, left ventricular mass index, urine albumin excretion, and occurrence of CV events.7, 9, 31 Future studies are needed to validate the use of these monitors in severely obese patients.32 Their use among patients diagnosed with atrial fibrillation is still under question, and further studies are needed in this group. If financial considerations dictate, a home recorder which performs 3 readings after a single activation without any delay could possibly be used for AOBP assessment. Some validated home BP devices such as the Omron HEM 7080‐IC33 with cost less than 100€ can offset the high cost of AOBP monitors (over 500€), and they should be better than an attended AOBP which risks conversation in the real world.

2.2. Observer presence or absence (attended vs unattended AOBP)

The principle of AOBP modality requires the patient to rest alone in a quiet room during the whole procedure of BP measurement to avoid the white coat effect.2 However, recent data suggest that unattended AOBP has no clear advantage over attended AOBP, provided that the latter is taken with an automated device and there is no talking.34 Specifically, the recent publication of Johnson et al, a post hoc analysis from SPRINT data, highlighted the aforementioned issue questioning how AOBP measurements were accomplished in the SPRINT, attended or unattended, and how the way of measuring affects outcome in terms of BP levels and CV disease risk.34 It is suggested that similar BP levels and CV disease risk reduction were observed in the intensive group participants regardless of whether the BP measurement technique used was attended or unattended. It should be mentioned that data from SPRINT are prospective and are from a carefully performed research study. Recently, AOBP readings have been shown to yield similar values when BP measurements were taken with or without medical staff. These readings were devoid of order effect and were comparable with awake ABP rather than conventional office values.35 The unattended office BP, however, is a guarantee that talking will be strictly avoided. On the other hand, recent data suggest that unattended AOBP cannot be used as an alternative to out‐of‐the‐office measurements, such as home BP.36 In a Spanish ABP registry, duplicate attended automated office BPs in 27,211 hypertensives were 25/11 mm Hg higher than the awake ABP for the systolic and diastolic BP, respectively.37 In any case, attended or unattended, obtained AOBP data close to the diagnostic thresholds should be evaluated very carefully in order to diagnose hypertension, since higher AOBP values may indicate the need to consider treatment.38

2.3. Rest period before BP measurement (preceding rest)

The BpTRU device is programmed to perform readings without a preceding rest, because of the five readings recorded.39 However, it is unclear whether the preceding rest period is always required. Studies of the two most commonly used devices, Omron HEM‐907XL and Microlife WatchBP Office, have been performed with the resting period due to fewer number of measurements performed compared to the BpTRU device.39 However, Colella et al, who used Omron HEM‐907XL with 0 and 5 minutes of preceding rest, concluded that when BP is in the lower normal range, AOBP recorded without rest had closer to the awake ABP values compared to readings taken after 5 minutes of rest.40 In another study, added rest before AOBP measurement did not result in a significant difference compared with standard AOBP measurement in comparison with awake ABP. Interestingly, another study with higher number of hypertensive patients also showed that when mean systolic AOBP values with or without preceding rest were ≥130 mm Hg, lower awake ABP values were obtained. In contrast, when systolic AOBP values with or without preceding rest were <130 mm Hg awake ABP yielded higher BP. Researchers suggested that AOBP may even be taken without preceding rest when systolic BP is <130 mm Hg and performed with preceding 5 minutes of rest period when BP values are above this threshold.41 It has been showed that although in SPRINT ABP ancillary study all values were higher than or at best equal to AOBP in both groups, the possibility of masked uncontrolled AOBP remains scatter as it has been showed that the prevalence of masked hypertension is low (4%) when all 3 visits for diagnosis were used.42 It should be mentioned that all methods for office BP produce lower mean values than the awake ABP at a systolic office BP <130 mm Hg. We do not as yet know the optimum method for recording office BP, although AOBP without rest and perhaps compared to the 24‐hour ABP and not the awake ABP may be the best method. Regarding the diastolic BP, in the range of 80 to 89 mm Hg, it is reasonable to screen for the presence of white coat hypertension using either daytime ABP or home BP monitoring prior to diagnosis of hypertension.18

2.4. Time intervals between BP measurements

There is little evidence concerning the time interval between the BP readings. BpTRU devices produce similar BP values regardless of whether the elapse time between the interval is 1 or 2 minutes.43 In another comparative study between BpTRU and Omron HEM 907, similar BP values were obtained when the elapse time was 1 minute.26 Of note, the elapse time between BpTRU readings is 1 minute from the start of one reading to the start of the next one, whereas with Omron HEM 907 and Microlife WatchBP Office the elapse time begins from the end of a reading till the start of the next one, suggesting that five readings with the BpTRU take about the same time as three readings with the other two types of devices.44 It has been previously mentioned that BpTRU device is not commercially available, and thus, the only fully automated devices remain the Omron HEM 907 XL and the Microlife Watch BP Office.

Interestingly, the recent meta‐analysis of Roerecke et al17 clearly shows that AOBP readings are similar to awake ABP readings. The authors recommend that “AOBP should now be the preferred method for recording BP in routine clinical practice to identify patients with possible hypertension,” followed by 24‐hour ABP or home measurements, to confirm the diagnosis of hypertension. This was further reinforced by the meta‐analysis of Pappacogli et al45

3. CONCLUSION

In everyday clinical practice, the preferred method for office BP measurement should be the AOBP technique as it provides BP values very close to the awake ABP because it is devoid of the “white coat effect.” AOBP readings should be performed with 5 minutes of preceding rest in every patient initially. When systolic BP is <130 mm Hg in repeated office visits, then the individual's BP is considered to be in the normal range. When AOBP readings remain in the hypertensive range of ≥130 or ≥140 mm Hg, according to the ACC/AHA and the ESC/ESH Guidelines, respectively, the diagnosis of hypertension should be confirmed by using out‐of‐office BP measurements, home BP monitoring, or ABP.

In conclusion, AOBP readings should be performed with 5 minutes of preceding rest in every patient, initially. When systolic BP is <130 mm Hg in repeated office visits, then the individual's BP is considered to be in the normal range, and AOBP may even be performed without a rest period in subsequent office visits.

CONFLICT OF INTEREST

None.

AUTHOR CONTRIBUTIONS

Emmanuel A. Andreadis, the corresponding author, is responsible for the design of the study, the preparation of the draft, and the completion of the whole manuscript. Charalampia V. Geladari participated in writing the draft. All authors critically edited the manuscript. All authors read and approved the manuscript.

Andreadis EA, Geladari CV, Angelopoulos ET. The optimal use of automated office blood pressure measurement in clinical practice. J Clin Hypertens. 2020;22:555–559. 10.1111/jch.13837