Research ArticleOriginal ResearchA

Comparing the Effects of White Coat Hypertension and Sustained Hypertension on Mortality in a UK Primary Care Setting

Martin G. Dawes, Gillian Bartlett, Andrew J. Coats and Edmund Juszczak
The Annals of Family Medicine September 2008, 6 (5) 390-396; DOI: https://doi.org/10.1370/afm.865

Article Figures & Data

Tables

  • Table 1.

    Baseline Demographic and Clinical Characteristics by Blood Pressure Category

    CharacteristicWhite Coat Hypertension (n=1,117)Sustained Hypertension (n=4,065)PValue
    Age, mean (SD), years53.1 (13.2)57.9 (12.1)<.001
    Male, No. (%)355 (31.8)1,981 (48.7)<.001
    Taking antihypertensive medication, No. (%)388 (34.7)1,287 (31.7).052
    Current smoker or exsmoker, No. (%)501 (44.8)1,959 (48.2).048
  • Table 2.

    Clinic and Ambulatory Blood Pressure by Blood Pressure Category

    MeasureWhite Coat Hypertension (n=1,117)Sustained Hypertension (n=4,065)Mean Difference (95% CI) [PValue]
    CI = confidence interval.
    Note: Values are expressed as mean (SD) or mean difference (SD).
    Systolic blood pressure, mm Hg
        Clinic159.5 (13.1)168.8 (15.6)9.2 (8.2–10.2) [<.001]
        Ambulatory126.9 (6.8)156.3 (14.9)29.4 (28.5–30.3) [<.001]
        Clinic minus ambulatory32.6 (14.5)12.4 (16.7)–
    Diastolic blood pressure, mm Hg
        Clinic94.5 (7.5)96.6 (8.3)2.1 (1.6–2.7) [<.001]
        Ambulatory83.2 (8.0)92.3 (10.2)9.2 (8.5–9.8) [<.001]
        Clinic minus ambulatory11.3 (8.9)4.3 (9.5)–
  • Table 3.

    Crude All-Cause Mortality Rate per 1,000 Years of Follow-up (95% Confidence Interval) by Blood Pressure Category

    CharacteristicWhite Coat Hypertension (n=1,117)Sustained Hypertension (n=4,065)
    Total population4.4 (3.1–6.0)10.2 (9.1–11.4)
        Sex
            Male5.0 (2.9–8.6)11.8 (10.2–13.8)
            Female4.1 (2.7–6.1)8.6 (7.3–10.2)
    Antihypertensive medication
        Yes6.3 (3.9–9.9)16.3 (13.9–19.2)
        No3.3 (2.1–5.3)7.4 (6.3–8.7)
    Smoking status
        Nonsmoker2.9 (1.7–4.9)9.3 (7.9–10.9)
        Smoker or exsmoker6.5 (4.3–9.8)11.2 (9.6–13.2)
    Age-group, years
        <500.9 (0.3–2.9)1.9 (1.2–3.2)
        50–593.3 (1.6–6.6)4.1 (3.0–5.7)
        60–697.7 (4.6–12.8)14.0 (11.6–16.8)
        ≥7014.9 (8.0–27.8)29.4 (24.8–34.8)
  • Table 4.

    Risks of All-Cause and Cardiovascular Mortality According to Characteristics

    All-Cause Mortality (n=355 Deaths)Cardiovascular Mortality (n =169 Deaths)
    CharacteristicHR95% CIPValueHR95% CIPValue
    HR = hazard ratio; CI = confidence interval.
    a Crude/unadjusted hazard ratio (estimated using univariate Cox regression model) for white coat hypertension vs sustained hypertension.
    b Adjusted hazard ratios (estimated using multivariate Cox regression model). Values were adjusted for blood pressure category, sex, age (continuous), smoking, antihypertensive medication use, and clustering at the practice level. Reference groups were as follows: blood pressure category: sustained hypertension; sex: female; smoking: never smokers; and antihypertensive medication use: taking medication.
    White coat hypertension
        Crudea0.430.30–0.60<.0010.430.29–0.63<.001
        Adjustedb0.640.42–0.97.040.630.39–1.02.058
    Male sexb1.661.34–2.06<.0011.951.47–2.59<.001
    Age (5-year increments)b1.611.52–1.71<.0011.631.50–1.77<.001
    Smoker or exsmokerb1.391.16–1.67<.0011.250.95–1.64.12
    Not taking antihypertensive medicationb0.750.61–0.93.0080.720.56–0.94.01

Additional Files

  • The Article in Brief

    Comparing the Effects of White Coat Hypertension and Sustained Hypertension on Mortality in a UK Primary Care Setting

    Martin G. Dawes , and colleagues

    Background Blood pressure measurements are of major importance, but they can be unreliable. Some patients have normal blood pressure when measured over time through a process called ambulatory blood pressure monitoring but high blood pressure when measured in the doctor's office (referred to as white coat hypertension). This study examines death rates in patients with white coat hypertension and compares them with those whose blood pressure is high in both the clinic and through ambulatory blood pressure monitoring.

    What This Study Found White coat hypertension carries significantly less risk of death than if the patient has high blood pressure in both the clinic and when measured by ambulatory blood pressure monitoring.

    Implications

    • The authors suggest the medical community consider whether to stop using office blood pressure measurements for routine screening and diagnosing high blood pressure.
    • Research is needed to evaluate how much risk can be reduced in patients with white coat hypertension who are treated with blood pressure-lowering therapy.

  • Annals Journal Club Selection:

    Sep/Oct 2008

    The Annals Journal Club is designed to encourage a learning community of those seeking to improve health care and health through enhanced primary care. Additional information is available on the Journal Club home page.

    The Annals of Family Medicine encourages readers to develop the 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

    Article for Discussion

    • Dawes MG, Bartlett G, Coats AJ, Juszczak E. Comparing the effects of white coat hypertension and sustained hypertension on mortality in a UK primary care setting. Ann Fam Med.2008;6(5):390-396.

    Discussion Tips

    This article describes a practice-based cohort study comparing outcomes among patients with white coat hypertension or sustained hypertension. It is amenable to a usual journal club discussion using the questions below as a starting point.

    Discussion Questions

    • What question is addressed by the article? Why does it matter? How does the question fit with what already is known 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 participants were selected? The exclusion criteria and drop outs? Are any biases likely to be important?
    2. How blood pressures and outcomes were measured?
    3. Confounding (false attribution of causality because two variables discovered to be associated actually are associated with a 3rd factor)?
    4. How information was interpreted?
    5. Chance?2
  • What are the main findings?
  • How transportable are the findings to your clinical setting?
  • How might you interpret these findings in light of a recent "call to action" to incorporate routine home blood pressure monitoring into clinical care?3
  • What might patients think of these findings? How does this study affect what you recommend to patients?
  • What are some next steps for applying the findings or answering other questions that this study raises?

    • Reference

    1. Stange KC, Miller WL, McLellan LA, et al. Annals journal club: It�s time to get RADICAL. Ann Fam Med. 2006;4:196-197. http://annfammed.org/cgi/content/full/4/3/196.
    2. Zyzanski SJ, Flocke SA, Dickinson LM. On the nature and analysis of clustered data. Ann Fam Med. 2004;2(3):199-200.
    3. Pickering TG, Miller NH, Ogedegbe G, Krakoff LR, Artinian NT, Goff D. Call to action on use and reimbursement for home blood pressure monitoring: a joint scientific statement from the American Heart Association, American Society of Hypertension, and Preventive Cardiovascular Nurses Association. J Cardiovasc Nurs. 2008;23(4):299-323.
Back to top

In this issue

Print
Download PDF
Article Alerts
Email Article
Citation Tools
Get Permissions

Jump to section

Subjects