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Current study
White Coat Hypertension
in General Practice
November 2002
Contents
1.
Introduction
White coat hypertension
is common. The prevalence is about 20% among those with persistent elevation
of clinic blood pressure. The incidence of target organ damage or cardiovascular
morbidity and mortality is significantly less when comparing white coat
hypertension with established hypertension.
24-hour ambulatory
blood pressure monitoring is the most frequent tool to measure the white
coat effects. It is recommended by the British hypertension society guidelines
and the Canadian hypertension society guidelines. Definition of white
coat hypertension is an elevated daytime clinic blood pressure to >=
140/90 mmHg; while the daytime ambulatory blood pressure remains normal,
i.e. <135/85 mmHg.
2.
Impact
For service:
Patients confirmed
white coat hypertension can exempt from unnecessary treatment and the
'label' of the chronic incurable disease; while patients with genuine
HT can comply better with treatment.
Clients with white
coat hypertension will be followed up at longer interval and advised on
home blood pressure monitor. Repeated ambulatory BP monitoring will be
arranged in years' time.
For surveys and
studies:
Case reviews can be
conducted to identify the characteristics of clients with white coat hypertension.
The demographic data
of patients will be collected, including social classes and psychological
diagnoses e.g. anxiety.
3.
Aims
To identify patients
potentially suffering from white coat hypertension using validated ambulatory
blood pressure monitors (ABPM). (TM-2420 model; validated by both US Association
for the Advancement of Medical Instrumentation and British Hypertension
Society.)
To conduct surveys
and studies on the epidemiology, course and outcomes of patients with
white coat hypertension, where local/ overseas data is lacking.
4.
Procedures
Selection of subjects:
- Repeated clinic
BP >= 140/90 while home BP (BP outside clinic) < 140/90
- Patients should
not be on anti-hypertensive treatment
- Must not be on
NSAIDs, sympathomimetics, liquorice at time of monitoring.
- For those who have
acute intercurrent illnesses, acute stressful events and unstable psychiatric
conditions, ABPM should be delayed.
- Hormones, steroids,
anxiolytics and anti-depressants may all affect BP. If initiation of
those drugs is deemed necessary, the subjects should be excluded. Stable
patients on long-term treatment of these medicine should NOT be excluded.
- Subjects with target
organ damage should be excluded.
Prior arrangement
should be made with doctor(s) responsible for ABPM.
Ambulatory BP monitors
were available in NTK Family Medicine Center and the three Families Clinics.
The explanation, set up and removal of monitor will be performed at the
clinic where the patient attended.
Interpretation of
the results was done by the Ambulatory BP team.
5.
Results
| 1. |
Up to October
2002, 157 clients fulfilling the above-mentioned criteria were selected
to measure 24-hour blood pressure by the ABPM. |
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| 2. |
73 of patients
(46.5%) were male and 84 (53.5%) were female clients. |
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| 3. |
The overall mean
age was 52.1 years. Mean age of male was 52.6 years while mean age
of female was 51.7 years. |
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| 4. |
32 of them (20.4%)
were diagnosed to have white coat hypertension. |
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| 5. |
8 (25%) of the
white coat hypertensives were male and 24 (75%) were female clients.
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| 6. |
The mean age
of white coat hypertensives was 57.7 years. Mean age of male was 62
years while mean age of female was 56.2 years. |
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| 7. |
The age ranged
from 42 to 74 years. The median was 60 years. |
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| 8. |
The educational
levels varied from no formal education to University level. |
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| 9. |
The occupation
included housewife, professionals like teachers and nurses, clerical
staff and manager grades. |
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| 10. |
11 (34.4%) of
the white coat hypertensives had the diagnosis of anxiety/ anxiety
symptoms in the records. |
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| 11. |
The actual number
of patients with anxiety/ anxiety symptoms was expected to be more,
if active and formal assessments were made. |
6.
Interpretations
| 1. |
20.4% of clinically
suspected white coats were diagnosed to have white coat hypertension
by 24-hour ABPM. |
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| 2. |
75% of the white
coat hypertensives were female clients. The mean ages of male and
female clients were comparable. |
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| 3. |
No relationship
was noted between different age groups and white coat effects. |
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| 4. |
No relationship
was noted between educational level and white coat effects. |
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| 5. |
No relationship
was noted between social class and white coat effects. |
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| 6. |
About 35% of
the white coat hypertensives were noted to have anxiety/ anxiety symptoms
in their records. The figure was likely to be under-estimated. |
7.
References
| 1. |
Use and interpretation
of ambulatory blood pressure monitoring: recommendations of the British
Hypertension Society
BMJ 22 April 2000; 320:1128-34 |
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| 2. |
National High
Blood Pressure Education Program Working Group Report on Ambulatory
Blood Pressure Monitoring
Archives of Internal Medicine 1990; 150:2270-80 |
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| 3. |
Management of
Hypertension after Ambulatory Blood Pressure Monitoring
Annals of Internal Medicine 1993; 118:833-837 |
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| 4. |
Ambulatory Blood
Pressure Monitoring and Blood Pressure Self-Measurement in the Diagnosis
and Management of Hypertension
Annals of Internal Medicine 1993; 118:867-882 |
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| 5. |
Automated Ambulatory
Blood Pressure Devices and Self-Measured Blood Pressure Monitoring
Devices: Their Role in the Diagnosis and Management of Hypertension
Annals of Internal Medicine 1993; 118:889-892 |
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| 6. |
Are occupational
stress levels predictive of ambulatory blood pessure in British GPs?
An exploratory study
Family Practice 2001; 18:92-94 |
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| 7. |
Measurement of
blood pressure: an evidence based review
BMJ 2001; 322:908-11 |
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| 8. |
ABC of hypertension:
Blood pressure measurement
BMJ 5 May 2001; vol.322: 1110-1114 |
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