The great myth of office blood pressure measurement

Clinical practice guidelines have traditionally recommended manual blood pressure (BP) measurement in the office setting as the standard method for diagnosing hypertension. In reality, manual BP in routine clinical practice is relatively inaccurate, over-diagnoses hypertension by provoking office-induced increases in BP and correlates poorly with both the awake ambulatory BP and target organ damage. The most recent guidelines recommend 24-h ambulatory BP and home BP for diagnosing hypertension. The advent of automated office BP (AOBP) represents a third alternative to conventional manual BP measurement, one that maintains the role of office BP readings in the diagnosis and management of hypertension. AOBP has three basic principles: multiple readings taken using a fully automated sphygmomanometer with the patient resting quietly alone. AOBP eliminates office-induced hypertension such that the cut-point for a normal AOBP is the same as for the awake ambulatory BP and home BP. As compared to routine manual office BP, AOBP provides more accurate BP readings, is more consistent during repeated office visits and in different settings and correlates better with both the awake ambulatory BP and target organ damage. The advantages of AOBP over manual BP measurement support its use in routine clinical practice.     

The conventional versus automated measurement of blood pressure in the office (CAMBO) trial: masked hypertension sub-study

OBJECTIVES:: To determine the prevalence of masked hypertension [normal office blood pressure (BP) with high awake ambulatory BP] using automated office BP (AOBP) or conventional manual office BP (MOBP) measurement in routine clinical practice. METHODS:: The prevalence of masked hypertension was evaluated on three consecutive visits during a median 6 months period in patients with systolic hypertension randomized to management with AOBP (n?=?140) or continued conventional MOBP (n?=?112) in routine primary care practice. AOBP was recorded using the automated BpTRU device with the patient resting alone in a quiet examining room. All patients underwent 24-h ambulatory BP monitoring. RESULTS:: The prevalence of masked hypertension on any one of three visits calculated using only SBP varied between 12 and 17% in the AOBP group compared with 19 and 22 % in the MOBP group. Masked hypertension was present on both of the first two visits in 7 and 12% and on all three visits in 6 and 7% of AOBP and MOBP patients, respectively. The prevalence for masked hypertension based upon both SBP and DBP was similar being 11-15% for AOBP and 19-20% for MOBP patients on single visits, but decreased to 6 and 10% when readings from the first two visits were used and to 4 and 6% when all three visits were used for the AOBP and MOBP groups, respectively. CONCLUSION:: The prevalence of masked hypertension is lower with AOBP compared with MOBP. The number of patients with masked hypertension decreases if the criteria for having this condition need to be met on multiple visits.     

Why use automated office blood pressure measurements in clinical practice?

Automated office blood pressure (AOBP) measurement with the patient resting alone in a quiet examining room can eliminate the white-coat effect associated with conventional readings taken by manual sphygmomanometer. The key to reducing the white-coat response appears to be multiple blood pressure (BP) readings taken in a non-observer office setting, thus eliminating any interaction that could provoke an office-induced increase in BP. Furthermore, AOBP readings have shown a higher correlation with the mean awake ambulatory BP compared with BP readings recorded in routine clinical practice. Although there is a paucity of studies connecting AOBP with organ damage, AOBP values were recently found to be equally associated with left ventricular mass index as those of ambulatory BP. This concludes that in contrast to routine manual office BP, AOBP readings compare favourably with 24-hour ambulatory BP measurements in the appraisal of cardiac remodelling and, as such, could be complementary to ambulatory readings in a way similar to home BP measurements.     

Comparison of awake ambulatory blood pressure and automated office blood pressure using linear regression analysis in untreated patients in routine clinical practice

The recent American hypertension guidelines recommended a threshold of 130/80 mmHg to define hypertension on the basis of office, home or ambulatory blood pressure (BP). Despite recognizing the potential advantages of automated office (AO)BP, the recommendations only considered conventional office BP, without providing supporting evidence and without taking into account the well documented difference between office BP recorded in research studies versus routine clinical practice, the latter being about 10/7 mmHg higher. Accordingly, we examined the relationship between AOBP and awake ambulatory BP, which the guidelines considered to be a better predictor of future cardiovascular risk than office BP. AOBP readings and 24‐hour ambulatory BP recordings were obtained in 514 untreated patients referred for ambulatory BP monitoring in routine clinical practice. The relationship between mean AOBP and mean awake ambulatory BP was examined using linear regression analysis with and without adjustment for age and sex. Special attention was given to the thresholds of 130/80 and 135/85 mmHg, the latter value being the recognized threshold for defining hypertension using awake ambulatory BP, home BP and AOBP in other guidelines. The mean adjusted AOBP of 130/80 and 135/85 mmHg corresponded to mean awake ambulatory BP values of 132.1/81.5 and 134.4/84.6 mmHg, respectively. These findings support the use of AOBP as the method of choice for determining office BP in routine clinical practice, regardless of which of the two thresholds are used for diagnosing hypertension, with an AOBP of 135/85 mmHg being somewhat closer to the corresponding value for awake ambulatory BP.     

BpTRUth: Do automated blood pressure monitors outperform mercury?

Manual measurement of blood pressure (BP) in the office (MOBP) is inferior in accuracy when compared with ambulatory BP measurements (ABPM) since it misses white coat and masked effects on BP. BpTRU, an automated office BP device (AOBP), has been reported to reduce white coat effect. We performed a retrospective review of the diagnostic accuracy of MOBP (taken by a trained nurse in clinical hypertension) and AOBP using the Bland-Altman method in hypertensive patients referred to a Renal Hypertension Clinic. In 329 hypertensive patients, the 95% limits of agreement between systolic AOBP and ABPM were ?31 mm Hg to 33 mm Hg and for MOBP and ABPM were ?27.8 mm Hg to 37.4 mm Hg. The bias between systolic MOBP and systolic ABPM was 4.9 mm Hg (95% confidence interval, 3.0–6.6 mm Hg) whereas the bias between the systolic AOBP and the systolic ABPM was ?3.2 (95% confidence interval, ?1.3 to ?5.0). AOBP did not improve treatment relevant classification errors compared with MOBP (28% vs. 23%; P = .052). Our data support findings by others showing that AOBP improves, but does not eliminate, white coat effect. The increased detection of white coat effect appears related to systematic downward bias by BpTRU. As a result, detection of masked effect is undermined by BpTRU.     

Comparability of Automated Office Blood Pressure to Daytime 24-Hour Ambulatory Blood Pressure

Background

Clinical practice guidelines endorse automated office blood pressure (AOBP) measurement as the preferred in-office measurement modality. However, recent data indicate that this method may underestimate daytime ambulatory BP. The objective of this study was to further assess the comparability of mean AOBP and daytime ambulatory BP in clinical practice.

Eliminating the Human Factor in Office Blood Pressure Measurement

Factors related to the physician/nurse and patient and their interaction are potential sources of error in manual office blood pressure (MOBP). The use of automated sphygmomanometers to record blood pressure (BP) with the patient alone reduces measurement error and minimizes anxiety‐related increases in BP, thus eliminating the “white‐coat” response. Comparative studies have shown the cut‐point for a normal automated office BP (AOBP), awake ambulatory BP, and home BP (<135/85 mmHg) to be similar, providing the patient does not rest for a prolonged period before the first AOBP reading, as recommended for MOBP measurement. AOBP should now replace MOBP in routine clinical practice.     

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

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.     

Performance of the automated BpTRU measurement device in the assessment of white-coat hypertension and white-coat effect

OBJECTIVES: BpTRU (VSM MedTech Ltd, Vancouver, Canada) is an automated oscillometric device that provides serial blood pressure measurements in an office setting in the absence of a healthcare professional. We sought to determine whether the white-coat effect is reduced by a blood pressure measurement protocol using BpTRU compared with casual office measurements. Secondarily, we also sought to determine whether a blood pressure measurement protocol using BpTRU reduced white-coat hypertension compared with the casual office measurements, and reduced white-coat effect and white-coat hypertension compared with blood pressure obtained by a research nurse. METHODS: Blood pressure was measured in 107 adult hypertensive patients referred for ambulatory blood pressure monitoring using an ambulatory blood pressure monitor, a standardized protocol by a trained research nurse, and a protocol using BpTRU (five readings over 25 min, using the 5-min blood pressure measurement interval setting). Casual office blood pressure was also recorded in the family physicians' offices. Using the mean daytime ambulatory blood pressure as the reference standard, the proportion of patients with white-coat effect and white-coat hypertension were determined for measurements obtained by BpTRU, the research nurse, and the family physicians' offices. RESULTS: Casual office blood pressure measurements demonstrated a white-coat effect in 39 (36.4%) patients; seven (6.5%) patients demonstrated a white-coat effect using BpTRU (P<0.0001). White-coat hypertension was also less common using BpTRU than with the casual office readings (13 vs. 1 patient, P<0.0001). White-coat effect was also reduced with BpTRU compared with the research nurse measurements. Unfortunately, percentage agreement for the diagnosis of hypertension between the protocol using BpTRU and the reference standard was only 48%. This resulted in substantial misclassification of hypertension by the BpTRU measurement protocol. CONCLUSIONS: Although BpTRU reduces white-coat effect and white-coat hypertension, blood pressure is underestimated by the device, leading to misclassification of hypertension. BpTRU, when set at 5-min blood pressure measurement intervals, should not be used in clinical practice.     

Canadian hypertension society guidelines for ambulatory blood pressure monitoring

The Canadian Hypertension Society has developed guidelines for the use of ambulatory blood pressure (BP) monitoring in clinical practice. Published articles with the best available levels of evidence were used to support the following recommendations:Physicians should only use ambulatory BP monitoring devices that have been validated independently using established protocols.A decision to withhold drug therapy based upon the ambulatory BP should take into account normal values for 24-h and awake ambulatory BP.Based upon studies on prognosis and a clinical trial based upon BP control as an outcome, ambulatory BP monitoring should be considered for untreated patients whenever an office-induced increase in BP is suspected.Ambulatory BP monitoring should be considered for treated patients suspected of having an office-induced increase in BP, including individuals with apparent resistance to drug therapy, symptoms suggestive of hypotension, and fluctuating office BP readings.Based upon studies on prognosis, changes in nocturnal BP should be taken into account in any decision to withhold drug therapy based upon the ambulatory BP.Further studies are required to determine whether the clinical benefit of antihypertensive therapy is more closely related to ambulatory or office BP.     

Use of an automated blood pressure recording device,the BpTRU,to reduce the "white coat effect" in routine practice

BACKGROUND: Patients often exhibit higher blood pressure (BP) readings in the doctor's office, a phenomenon known as the white coat effect. This study examines the presence of a physician in the examining room as a possible factor in provoking a white coat effect. METHODS: Blood pressure measurements taken by an automated BP recording device, the BpTRU (VSM MedTech Ltd., Vancouver, BC, Canada) with the patient alone in the examining room, were compared with the following: (1) BP taken by the patient's family physician; (2) BP taken on the first visit to a hypertension specialist; (3) BP measured by a trained research technician and (4) the mean awake ambulatory BP (ABP). The BpTRU and trained research technician readings were taken outside of the office (treatment) setting in an ABP research unit. RESULTS: Blood pressure readings (mm Hg, mean +/- SEM) taken by the BpTRU (155 +/- 5/88 +/- 2) tended to be lower than for the family physician (166 +/- 4/89 +/- 3) and the hypertension specialist (174 +/- 5/92 +/- 2; P <.001). However, BP taken by the trained research technician (158 +/- 4/90 +/- 2) was similar to the value obtained by the BpTRU. The mean awake ABP was lower (P < 0.01) than the other four BP values. CONCLUSIONS: Use of an automated BP recording device outside of the office (treatment) setting can partly eliminate the white coat effect. A similar finding was observed with readings taken by a trained research technician under similar conditions. Referral of patients to nonoffice settings for automated BP recordings may provide a more accurate estimate of a patient's BP status, with partial elimination of the white coat effect associated with readings taken by a physician.     

Blood pressure measurement: Should technique define targets?

Accurate assessment of blood pressure (BP) is the cornerstone of hypertension management. The objectives of this study were to quantify the effect of medical personnel presence during BP measurement by automated oscillometric BP (AOBP) and to compare resting office BP by AOBP to daytime average BP by 24‐h ambulatory BP monitoring (ABPM). This study is a prospective randomized cross‐over trial, conducted in a referral population. Patients underwent measurements of casual and resting office BP by AOBP. Resting BP was measured as either unattended (patient alone in the room during resting and measurements) or as partially attended (nurse present in the room during measurements) immediately prior to and after 24‐h ABPM. The primary outcome was the effect of unattended 5‐min rest preceding AOBP assessment as the difference between casual and resting BP measured by the Omron HEM 907XL. Ninety patients consented and 78 completed the study. The mean difference between the casual and Omron unattended systolic BP was 7.0 mm Hg (95% confidence interval [CI] 4.5, 9.5). There was no significant difference between partially attended and unattended resting office systolic BP. Resting office BP (attended and partially attended) underestimated daytime systolic BP load from 24‐h ABPM. The presence or absence of medical personnel does not impact casual office BP which is higher than resting office AOBP. The requirement for unattended rest may be dropped if logistically challenging. Casual and resting office BP readings by AOBP do not capture the complexity of information provided by the 24‐h ABPM.     

Comparison between an automated and manual sphygmomanometer in a population survey

BACKGROUND: An automated sphygmomanometer, the BpTRU, was used in a blood pressure (BP) survey of 2,551 residents in the province of Ontario. Automated BP readings were compared with measurements taken by a mercury sphygmomanometer under standardized conditions in a random 10% sample. METHODS: BP was recorded in 238 individuals in random order using both a standard mercury device and an automated BP recorder, the BpTRU. All subjects rested for 5 min prior to the first BP reading, which was then discarded. The mean of the next three readings was obtained using the mercury device whereas the BpTRU was set to record a mean of five readings taken at 1 min intervals with subjects resting alone in a quiet room. RESULTS: The mean s.d. BP with the automated device was 115 +/- 16/71 +/- 10 mm Hg compared to 118 +/- 16/74 +/- 10 mm Hg for the manual BP (P < 0.001). A systolic BP > or = 140 mm Hg was present for 16 automated and 19 manual readings. Similarly, the diastolic BP was > or = 90 mm Hg for 9 automated and 14 manual readings. Linear regression analysis showed that automated BP was a significant (P < 0.001) predictor of both manual systolic and diastolic BP. CONCLUSION: Conventional manual BP readings can be replaced by readings taken using a validated, automated BP recorder in population surveys. The slightly lower readings obtained with the BpTRU device (in the context of reduced observer-subject interaction) may be a more accurate estimate of BP status.     

Automated measurement of blood pressure in routine clinical practice

In recent years, automated devices have been developed to record blood pressure (BP) accurately in the home and during usual daily activities. Clinical outcome studies have clearly shown home BP and 24-hour ambulatory BP to be significantly better predictors of future cardiovascular events compared with BP recorded in the office setting using mercury sphygmomanometry. It is also now possible to measure office BP with the patient resting quietly alone in the examining room using an automated device. Studies in routine clinical practice using this approach have demonstrated that automated office BP can eliminate most of the white coat effect seen with manual BP measurement. The automated office BP also correlates significantly better than does the routine office BP with the 24-hour ambulatory BP, the gold standard for predicting risk of future cardiovascular events. Sufficient evidence now exists to consider incorporating automated office BP into an algorithm for diagnosing hypertension.     

Automated office blood pressure measurements obtained with and without preceding rest are associated with awake ambulatory blood pressure

Automated office blood pressure (AOBP) measurement, attended or unattended, eliminates the white coat effect (WCE) showing a strong association with awake ambulatory blood pressure (ABP). This study examined the difference in AOBP readings, with and without 5 minutes of rest prior to three readings recorded at 1‐min intervals. Cross‐sectional data from 100 randomized selected hypertensives, 61 men and 39 women, with a mean age of 52.2 ± 10.8 years, 82% treated, were analyzed. The mean systolic AOBP values without preceding rest were 127.0 ± 18.2 mm Hg, and the mean systolic AOBP values with 5 minutes of preceding rest were 125.7 ± 17.9 mm Hg (P = .05). A significant order effect was observed for the mean systolic BP values when AOBP without 5 minutes of preceding rest was performed as the first measurement (130.0 ± 17.7 vs 126.5 ± 16.2, P = .008). When we used a target systolic AOBP ≥ 130 mm Hg, awake ABP yielded lower readings, while at a target systolic AOBP value of < 130 mm Hg higher awake ABP values were obtained. Our findings indicate that systolic AOBP can be initially checked without any preceding rest and if readings are normal can be accepted. Otherwise, when AOBP is ≥ 130 mm Hg, measurements should be rechecked with 5 minutes of rest.     

Home blood pressure is as reliable as ambulatory blood pressure in predicting target-organ damage in hypertension

BACKGROUND: Our objective was to assess the value of home blood pressure (BP) monitoring in comparison to office BP measurements and ambulatory monitoring in predicting hypertension-induced target-organ damage. METHODS: Sixty-eight untreated patients with hypertension with at least two routine prestudy office visits were included (mean age, 48.6 +/- 9.1 [SD] years; 50 men). Office BP was measured in two study visits, home BP was measured for 6 workdays, and ambulatory BP was monitored for 24 h. All BP measurements were obtained using validated electronic devices. Target-organ damage was assessed by measuring the echocardiographic left-ventricular mass index (LVMI), urinary albumin excretion rate (AER) in two overnight urine collections, and carotid-femoral pulse-wave velocity (PWV) (Complior device; Colson, Garges-les-Gonesse, Paris, France). RESULTS: The correlation coefficients of LVMI with office BP were 0.24/0.15 (systolic/diastolic), with home BP 0.35/0.21 (systolic, P < .01), and with 24-h ambulatory BP 0.23/0.19, awake 0.21/0.16, and asleep 0.28/0.26 (asleep, both P < .05). The correlation coefficients of AER with office BP were 0.24/0.31 (diastolic, P < .05), with home BP 0.28/0.26 (both P < .05), and with 24-h ambulatory BP 0.25/0.24, awake 0.24/0.25 (diastolic, P < .05), and asleep 0.26/0.18 (systolic, P < .05). There was a trend for negative correlations between PWV and diastolic BP measurements (not significant). In multiple-regression models assessing independent predictors of each of the three indices of target-organ damage, systolic home BP and age were the only independent predictors of increased LVMI that reached borderline statistical significance. CONCLUSIONS: These data suggest that home BP is as reliable as ambulatory monitoring in predicting hypertension-induced target-organ damage, and is superior to carefully taken office measurements.     

Unattended automated office blood pressure measurement: Time efficiency and barriers to implementation/utilization

Unattended automated office blood pressure (BP) measurement (u‐AOBP) improves office BP measurement accuracy and reduces white‐coat BP elevation, but there are reservations about its time efficiency in primary care. We used time‐stamp methodology to measure u‐AOBP procedure times performed without a rest period in 130 patients during routine clinic visits to three primary care clinics with 2.5‐4.9 years u‐AOBP experience. We documented the clinical activities of 30 medical assistants during the u‐AOBP procedures. We also assessed MA and clinician satisfaction and knowledge about u‐AOBP performance and interpretation. Median u‐AOBP procedure time was <5 minutes, and MAs engaged in productive clinical activities during 83% of the procedures. Ninety‐three percent of MAs and 100% of clinicians in the clinics agreed that u‐AOBP is an efficient method to improve hypertension management. Barriers to effective u‐AOBP implementation and ongoing utilization included initial difficulty incorporating u‐AOBP into clinic workflow and medical staff knowledge deficiencies concerning correct u‐AOBP performance and interpretation despite prior training and experience with the procedure. Intensive u‐AOBP education and training programs are needed to facilitate effective u‐AOBP implementation into primary care. The time required to perform u‐AOBP can be utilized productively by staff.     

Clinical decision-making in hypertension using an automated (BpTRU) measurement device

Mercury sphygmomanometers are being removed from clinical practice in the United States due to environmental concerns about mercury toxicity. Accurate blood pressure measurement is central to high-quality hypertension management. In this study of 106 patients, the BpTRU(TM) device was compared to nurse blood pressure measurements that complied with all the JNC VII/American Heart Association guidelines in evaluation of a random casual blood pressure. The intermethod difference in systolic blood pressure was +1.8+/-5.1 mmHg, and for diastolic blood pressure it was 4.8+/-5.1 mmHg (both P<0.001). For the primary study end point of clinical decision-making, there was 92% (97/106) agreement between the hypertension nurse specialist and the BpTRU (kappa 0.8280, 95% confidence interval, 0.721-0.9350). The oscillometric blood pressure measurement with the BpTRU is recommended as a replacement for poorly performed auscultatory blood pressure measurement in clinical practice.     

Étude PASTIS : pression artérielle sans intervention de soignant. Évaluation d’une mesure de la pression artérielle automatisée en cabinet

ObjectiveThe evaluation of automated office blood pressure (AOBP) measurement compared to 24-hour ambulatory BP monitoring (ABPM), Home BP measurement and manual BP.Patients and methodologyA total of 123 hypertensive patients were included. Overall, 68 completed the 4 measurement: Manual BP in the office (Omron 705 CP 3 measurements), ABPM (Spacelab of 96 measurement/per 24 hours), Home BP (18 measurement during 3 days), AOBP using the SPRINT methodology: lying patient, isolated with an automatic measurement (Dinamap) every minutes during 8 minutes (average of the last 3 measurement). Twenty-two out of 123 patients (26%) did not complete the Home BP measurement.ResultsThe average of AOBP measurement using SPRINT is 132 ± 12/69 ± 9 mmHg, of ABPM 134 ± 13/79 ± 9, of Home BP: 135 ± 13/70 ± 13 and of manual BP: 138 ± 13/72 ± 11 mmHg The Bland & Altman method highlight that the AOBP, the ABPM and home BP measurement are 3 substitutable methods. The confidence interval is smaller between the ABPM and the AOBP than with the home BP.ConclusionThe automated office blood pressure, as the Home BP measurement, can be considered a reliable substitute for the ABPM, when the later is not accessible, and when a repeated therapeutic evaluation is needed, or when the home BP measurement is not done. These results encourage us to use it more frequently as the Canadian Hypertension Education Program recommend it.     

Ambulatory Blood Pressure Monitoring as an Investigative Tool for Characterizing Resistant Hypertension and Its Rational Treatment

Ambulatory blood pressure (BP) monitoring has matured into a useful methodology that obtains automated measurements of brachial artery BP during a 24-hour period. Cardiovascular outcomes in the treated patient with hypertension are often better predicted by ambulatory BP than by office pressures. Consensus guidelines have advocated lower goals of treated office BP in the majority of patients with hypertension; guidelines for the goal of ambulatory BP are needed as well. Recently, prospective cohort studies have shown that individuals whose clinic pressure is relatively normal but whose 24-hour BP is elevated are more likely to have a cardiovascular event than individuals with both normal clinic BP and ambulatory BP. Along with the knowledge gained from analyses of higher-risk hypertension patients, recommendations can now be made for how to use ambulatory BP monitoring in clinical practice. For example, ambulatory BP monitoring may be useful in verifying 24-hour control in high-risk patients whose office BP appears to be normal at rest or during the peak effect time of their antihypertensive agents. Evidence is mounting from studies that support the use of ambulatory BP monitoring in patients with resistant hypertension at the time of diagnosis and following clinically guided therapy.