Eliminating the Human Factor in Office Blood Pressure Measurement

Abstract

The letter of Hiremath and colleagues 1 provides an opportunity to clarify several aspects of automated office blood pressure (AOBP) measurement and to address the concerns they have raised. The basic principles of AOBP include multiple readings taken with a fully automated device with the patient resting quietly alone. As Hiremath and colleagues have noted, AOBP is now explicitly identified as an alternative to manual office blood pressure (MOBP) in various guidelines, including the British National Institute for Health and Clinical Excellence [NICE] report, 2 which recommended that MOBP not be used to diagnose hypertension. Numerous studies have documented the superiority of AOBP over MOBP in terms of accuracy and validity, including the elimination of the white-coat effect.It is unfortunate that Hiremath and colleagues dismiss the evidence supporting the use of AOBP while defending the findings in their recent study 3 in an attempt to discredit AOBP. They make several claims that are invalid. They persist with their belief that an AOBP reading should be preceded by a period of rest, despite at least 10 studies reporting similar values for AOBP and awake ambulatory BP (AABP) without any rest before readings. 4 They quote the findings from a single study reported by Lalonde and colleagues at a scientific meeting to support their position. However, this study used the same sequential, before and after design to compare MOBP with AOBP readings and their respective relationship to the AABP. In both instances, AOBP was preceded by several MOBP readings and 5 minutes of rest. As expected, the mean AOBP values were lower than the AABP, in contrast to the 10 studies mentioned above. As stated in my commentary, when comparing two different methods of blood pressure (BP) measurement, the sequence of recording the readings should be randomized, otherwise the second readings-regardless of the technique usedwill tend to be lower.Hiremath and colleagues also incorrectly imply that inclusion of AOBP in various guidelines is accompanied by a recommendation for a 5-minute period of rest. They seem unaware that our own Canadian (Canadian Hypertension Education Program [CHEP]) guidelines since 2011 specifically state that there should be "no specified period of rest" before AOBP readings are taken. 5The statement by Hiremath and colleagues that I continue "to promote AOBP as a surrogate for daytime ABPM" is incorrect. None of the articles from our group has ever stated that AOBP can substitute (the dictionary meaning of "surrogate") for ABPM. As indicated in my commentary, "ambulatory BP. . .has a pre-eminent position in the guidelines" and ABPM is "considered to be a gold standard for predicting future cardiovascular risk in relation to BP status."Hiremath and colleagues also state that "it is curious that Dr Myers has chosen to ignore the wide limits of agreement between AOBP and ABPM." Given that I was the first person to describe the confidence limits of AOBP using Bland-Altman analysis and have reported this analysis for AO...

Reply to Dr Myers' Commentary on the Use of Automated Blood Pressure Machines in Office Blood Pressure Measurements

“…1 Dr Myers suggests that the absence of resting for AOBP readings in the Conventional Versus Automated Measurement of Blood Pressure in the Office (CAMBO) trial 2 accounts for the discrepancy between those results and our data. 3 Indeed, a recent study by Nikolic and colleagues 4 reported that office BP does decrease with resting time (by À4.1 mm Hg from 5 to 10 minutes).…”

“…We reviewed the commentary 1 by Dr Myers wherein he suggests that casual automated office blood pressure (AOBP) should replace resting manual office blood pressure (MOBP), and that casual readings taken with AOBP are similar to awake ambulatory blood pressure monitoring (ABPM). 1 Dr Myers suggests that the absence of resting for AOBP readings in the Conventional Versus Automated Measurement of Blood Pressure in the Office (CAMBO) trial 2 accounts for the discrepancy between those results and our data.…”

“…We therefore find it curious that Dr Myers has chosen to ignore the wide limits of agreement between AOBP and ABPM as assessed by Bland-Altman analysis and continues to promote AOBP as a surrogate for daytime ABPM. 1 While clearly not a surrogate for ABPM when subjected to rigorous statistical testing, AOBP is endorsed by a number of national professional organizations in their guidelines for the diagnosis and management of office hypertension. According to these guidelines (National Institute for Health and Clinical Excellence [NICE], 7 European Society of Hypertension [ESH], 8 and Canadian Hypertension Education Program [CHEP], 9 to name just a few), AOBP should be measured in a similar manner as MOBP.…”

Systolic Blood Pressure Intervention Trial (SPRINT) and Target Systolic Blood Pressure in Future Hypertension Guidelines

“…14 The automated office BP protocol with 5 minutes of rest leads to SBP 6.9 mm Hg lower than daytime ambulatory values, 15,16 which matches the difference between automated office SBP and daytime ambulatory SBP with SPRINT intensive treatment.…”

“…In fact, BP values in NHANES participants likely would have been significantly lower if measured using SPRINT methods. [14][15][16][17]27,28 Third, unlike SPRINT, our NHANES analysis did not include individuals with untreated SBP 130 to 139, because the Seventh Joint National Committee defined hypertension in untreated adults as an SBP ≥140 during 2003-2013, 29 which includes the time period of our NHANES analysis. Adults with diabetes mellitus comprised the largest group of patients with an SBP <140 (goal <130), 29 and they were excluded from SPRINT.…”