Research ArticleOriginal ResearchA

A Novel Approach to Office Blood Pressure Measurement: 30-Minute Office Blood Pressure vs Daytime Ambulatory Blood Pressure

Mark C. van der Wel, Iris E. Buunk, Chris van Weel, Theo A. B. M. Thien and J. Carel Bakx
The Annals of Family Medicine March 2011, 9 (2) 128-135; DOI: https://doi.org/10.1370/afm.1211

Article Figures & Data

Figures

  • Figure 1
    Figure 1

    Course of mean systolic blood pressure during 30 minutes of measurement.

    Note: Error bars represent 95% confidence intervals of the standard error of the mean.

  • Figure 2a
    Figure 2a

    Bland-Altman plot of difference in mean arterial pressure between 30-minute OBPM and daytime ABPM against mean mean arterial pressure.

    ABPM = 24-hour ambulatory blood pressure monitoring; MAP = mean arterial pressure; OBPM = office blood pressure measurement.

  • Figure 2b
    Figure 2b

    Bland-Altman plot of difference in systolic blood pressure between 30-minute OBPM and daytime ABPM against mean systolic blood pressure.

    ABPM = 24-hour ambulatory blood pressure monitoring; OBPM = office blood pressure measurement.

  • Figure 2c
    Figure 2c

    Bland-Altman plot of difference in diastolic blood pressure between 30-minute OBPM and daytime ABPM against mean diastolic blood pressure.

    ABPM = 24-hour ambulatory blood pressure monitoring; OBPM = office blood pressure measurement.

Tables

  • Table 1

    Characteristics of Study Population

    VariableValue
    Population studied, No.84
    Age, mean (SD), y57 (13.9)
    Sex, %
     Female61
     Male39
    Body mass index, mean (SD)26.5 (4.3)
    Smoker, %17
    Antihypertensive medication, %
     Yes51
     No49
    Reason of referral for 24-hr ABPM, %
     Suspected white-coat hypertension45
     Diagnosis of hypertension38
     Treatment evaluation12
     Other5

    • ABPM = 24-hour ambulatory blood pressure monitoring.

  • Table 2

    Blood Pressure Levels for Daytime ABPM and 30-Minute OBPM

    Measurement30-min OBPM (SD)Daytime ABPM (SD)Δ 30-min OBPM–ABPM (95% CI)SDD
    Mean arterial pressure, mm Hg104 (12)103 (11)2 (0 to 3)a7
    Systolic blood pressure, mm Hg141 (17)141 (14)0 (−2 to 2)10
    Diastolic blood pressure, mm Hg84 (11)82 (11)2 (0 to 3)b6

    • ABPM = ambulatory blood pressure monitoring; CI = confidence interval; OBPM = office blood pressure measurement; SDD = standard deviation of the difference of the mean.

    • Note: Because of rounding, figures may not add up correctly.

    • ↵a P=.03.

    • ↵b P=.008.

  • Table 3

    Comparison of Patients Classified by Hypertension Subtypes Between 30-Minute OBPM and Daytime ABPM

    Subtype30-min OBPM No.Daytime ABPM No.
    Normotensive1815
    White-coat hypertension1313
    Masked hypertension14
    Sustained hypertension5252

    • ABPM = ambulatory blood pressure monitoring; OBPM = office blood pressure measurement.

    • Note: There were 87% of patients similarly classified by both 30-minute OBPM and daytime ABPM.

Additional Files

  • The Article in Brief

    A Novel Approach to Office Blood Pressure Measurement: 30-Minute Office Blood Pressure vs Daytime Ambulatory Blood Pressure

    Mark C. Van der Wel , and colleagues

    Background Office blood pressure measurement can be inaccurate as a result of white-coat effect (in which patients have high blood pressure in a clinical setting but not in other settings, perhaps resulting from anxiety) or other biases. Twenty-four hour blood pressure monitoring is often more accurate, but can be costly, difficult to implement, and not suitable for all patients. This study examined a new method of measuring office blood pressure through a series of automated measurements taken with the patient sitting alone in a quiet room.

    What This Study Found Sitting for 30 minutes in a quiet room with automated blood pressure measurements is as useful in detecting white-coat hypertension as is 24-hour continuous blood pressure monitoring.

    Implications

    • The authors conclude that the automated 30-minute blood pressure measurement technique is a valid, useful, office-based alternative to 24-hour blood pressure monitoring, allowing physicians to overcome such problems as observer bias and the white-coat effect, while saving patients from the hassle of 24-hour monitoring.

  • Annals Journal Club:

    Mar/Apr 2011

    Guided Care

    The Annals of Family Medicine encourages readers to develop a learning community of those seeking to improve health care and health through enhanced primary care. You can participate by conducting a RADICAL journal club and sharing the results of your discussions in the Annals online discussion for the featured articles. RADICAL is an acronym for Read, Ask, Discuss, Inquire, Collaborate, Act, and Learn. The word radical also indicates the need to engage diverse participants in thinking critically about important issues affecting primary care and then acting on those discussions.1

    How it Works

    In each issue, the Annals selects an article or articles and provides discussion tips and questions. We encourage you to take a RADICAL approach to these materials and to post a summary of your conversation in our online discussion. (Open the article online and click on "TRACK Comments: Submit a response.") You can find discussion questions and more information online at: http://www.AnnFamMed.org/AJC/.

    CURRENT SELECTION

    Article for Discussion

    • van der Wel MC, Buunk IE, van Weel C, Thien TABM, Bakx JC. A novel approach to office blood pressure measurement: 30-minute office blood pressure vs daytime ambulatory blood pressure. Ann Fam Med. 2011;9(2):128-135.

    Discussion Tips

    Sometimes, for patients for whom regular, in-office, blood pressure readings seem unreliable, we resort to 24 hours of ambulatory blood pressure measurement. This study examines a novel use of this ambulatory blood pressure measurement technology, comparing full daytime ambulatory monitoring with 30 minutes of in-office blood pressure monitoring.

    Discussion Questions

    • What question(s) are addressed by this article?
    • How does this study advance beyond previous research and clinical practice on this topic?
    • How strong is the study design for answering the question?
    • To what degree can the findings be accounted for by:
    1. How patients were selected, excluded, or lost to follow-up?
    2. How the main variables were measured?
    3. Confounding (false attribution of causality because 2 variables discovered to be associated actually are associated with a 3rd factor)?
    4. Chance?
  • What are the main study findings?
  • Do any of the data help you to better understand the phenomenon of white-coat hypertension?
  • How comparable is the study sample to similar patients in your practice? What is your judgment about the transportability of the findings?
  • How might this study change your practice?
  • For which patients might you use regular in-office blood pressure measurement? 30-minute measurement? 24-hour or daytime ambulatory monitoring?
  • How might this new method be incorporated into your practice? Are any of the differences in how you might implement this technology and how it was tested in this study problematic?
  • What important researchable questions remain?

    • References

    1. Stange KC, Miller WL, McLellan LA, et al. Annals journal club: It�s time to get RADICAL. Ann Fam Med. 2006;4(3):196-197. http://annfammed.org/cgi/content/full/4/3/196.
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