Journal of Human Hypertension (2000) 14, 355–358
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ORIGINAL ARTICLE
Difference in blood pressure, but not in
heart rate, between measurements
performed at a health centre and at a
hospital by one and the same physician
I Enström1, K Pennert2 and L H Lindholm3
1
Kävlinge Health Centre, Kävlinge, Sweden; 2Clinical Data Care in Lund AB, Sweden; 3Department of
Family Medicine, Umeå University Hospital, Sweden
Background: Blood pressure (BP) has been found to
vary between examiners, for example it is often higher
when measured by a physician than by a nurse. Whether
the location for the physician-measured BP is also a
source of variation has, however, not been studied.
Hence, we found it of interest to find out if the location
used for examination was of any significance.
Objective: To explore if BP and/or heart rate measured
in the same subjects by the same general practitioner
in the health centre and at the hospital, differed.
Method: Twenty-five hypertensive and 25 age-matched
normotensive middle-aged men had their office BP and
heart rate recorded by one and the same female general
practitioner (IE) who was well known to them, at both
the health centre before ambulatory BP equipment was
attached to the subject and at the clinical physiological
department before an exercise test. The hypertensive
patients performed an exercise test and ambulatory BP
was measured before and after being treated.
Results: The hypertensive patients’ office BP was lower
at the health centre than at the hospital, both when they
were untreated and after they were treated. The difference (systolic/diastolic (s.d.)) was 9.4/6.0 (7.4/2.7)
mm Hg (P ⬍ 0.001 for systolic and diastolic BP), when
they were untreated. Corresponding figures when they
were treated were 5.4/4.0 (9.4/4.7) mm Hg, a significant
difference in diastolic BP (P ⬍ 0.001). The normotensive
subjects also had a lower office BP at the health centre
than at the hospital. The difference (systolic/diastolic
(s.d.) was 1.8/5.3 (7.0/5.0) mm Hg (P ⬍ 0.001 for diastolic
BP). Heart rate did not differ between recordings in the
health centre and in the hospital, either in the hypertensives or in the normotensives.
Conclusion: Office BP differed significantly between
measurements performed in the health centre and at the
hospital. Hence, being examined at a hospital seemed
to be a stronger stimuli in most patients than to be
examined in a health centre. When diagnosing or evaluating treatment in hypertension, this may have implications.
Journal of Human Hypertension (2000) 14, 355–358
Keywords: blood pressure; hypertensives; normotensives; health centre; hospital
Introduction
It has been shown that the usual procedure for measuring blood pressure (BP) by a doctor is commonly
associated with rises in systolic and diastolic BP.1
The error of overestimation of BP inherent in cuff
BP measurement by a physician has been found not
to be avoided even by repeat visits over a short
time.2 This phenomenon has been defined as a
white-coat effect.3 In view of this we found it of
interest to elucidate if other factors such as the place
for the BP examination also had an influence on the
BP. Therefore, we analysed data from a former study
where office BP had been measured in a health
centre and at a university hospital in the same subjects by one and the same general practitioner who
Correspondence: Inger Enström, Kävlinge Health Centre, 244 31
Kävlinge, Sweden
Received 13 September 1999; revised and accepted 29 February
2000
was well known to them. The subjects were both
hypertensives and normotensives. We wanted to
elucidate whether BP values and/or heart rate measured in the health centre differed from those measured in a hospital.
Subjects and methods
Twenty-five previously untreated male hypertensives, found in a BP screening project in a municipality in southern Sweden,4 took part in a randomised cross-over study comparing 50 mg atenolol and
20 mg enalapril.5 Their mean age was 52.1 (range
40–65) years. A prerequisite for inclusion in that
study was a diastolic BP ⭓95 mm Hg (mean of two
recordings after 5 min supine bed rest) at three separate visits. The 16-week study was separated into
four 4-week treatment periods where each of the two
double-blind active treatment periods were preceded by a single-blind placebo period. At the end
of each 4-week treatment period BP was recorded at
Difference in BP, but not HR, measured at a health centre
I Enström et al
356
rest, during 24-h continuous monitoring and during
dynamic and isometric exercise. The ambulatory BP
equipment was attached to the patient at Kävlinge
Health Centre and the exercise test took place at the
Clinical Physiological Department, Lund University
Hospital. Both these examinations were preceded by
a 5-min supine bed rest BP measurement (two
recordings).
The 25 age-matched male normotensives, who
were found in the same screening project,4 had a
screening diastolic BP of ⬍90 mm Hg. They performed ambulatory BP and exercise test once.
Identical mercury manometers and cuffs were
used for the resting BPs. Diastolic BP was phase V
and was measured to the nearest 2 mm Hg. Deflation
was performed by pressing the knob that automatically and smoothly deflates the air. The same female
general practitioner (IE) working at the health
centre, measured resting BP and heart rate, applied
the ambulatory BP equipment, supervised the exercise test and instructed the participants.
Statistical methods
Standard statistics such as mean, standard deviation, minimum and maximum, were used to summarise and present the data. Differences in BP and
heart rate recorded at the health centre and at the
hospital were tested by the use of a Student’s onesample t-test. All tests were two-tailed and P-values
less than 0.05 regarded as statistically significant.
All analyses were performed using the statistical
package SAS version 6.11 running under Windows
95.
Figure 1 Hypertensives—untreated. Comparison between BP
readings at the health centre and at the hospital.
Results
The hypertensives office BP was lower at the health
centre than at the hospital, both as untreated and
treated. When untreated 21 of the 25 patients had
higher systolic BP and all 25 had higher diastolic
BP at the hospital (Figure 1) and when treated the
corresponding figures were 19 for systolic and 21 for
diastolic BP (Figure 2). The difference was statistically significant both for systolic and diastolic BP
when they were untreated and for diastolic BP when
they were treated (Table 1). The normotensives also
had lower office BP at the health centre than at the
hospital. Sixteen had higher systolic and 22 higher
diastolic BP at the hospital (Figure 3). The difference
for diastolic BP was statistically significant (Table
1). Heart rate did not differ between recordings in
the health centre and the hospital in either the
hypertensives or in the normotensives (Table 1).
Discussion
We found that office BP measured by the same general practitioner in the same subjects was lower at
the health centre than at the hospital, both in the
hypertensives and in the normotensives. The difference was statistically significant for diastolic BP. In
the hypertensive patients, when untreated, systolic
BP also differed significantly between measurements at the hospital and at the health centre. Heart
Journal of Human Hypertension
Figure 2 Hypertensives—treated. Comparison between BP readings at the health centre and at the hospital.
rate, however, did not differ between the places
used for examination, either in the hypertensives or
in the normotensives.
The principle of the ‘law of the initial value’, indicates that the higher the baseline level of any variable, the higher the increase obtained following a
certain stimulus. Hence, a high average of all BP
readings is associated with greater pressure variability.6 However, Mancia et al2 in a study of physician-measured office BP found that the magnitude
of the intersubject variability is independent of the
patient’s baseline BP.2 In concordance with that
Difference in BP, but not HR, measured at a health centre
I Enström et al
357
Table 1 Blood pressure (mm Hg) and heart rate (beats/min) at the health centre and at the hospital
Health centre
(mean)
Hospital
Health centre/hospital
P-value
(s.d.)
(mean)
(s.d.)
(mean)
(s.d.)
Hypertensives—untreated
Systolic BP
153.1
Diastolic BP
99.8
Heart rate
72.8
14.1
4.0
7.6
162.4
105.8
72.5
15.1
4.7
10.7
−9.4
−6.0
0.3
7.4
2.7
6.3
⬍0.001
⬍0.001
⬎0.40
Hypertensives—treated
Systolic BP
142.9
Diastolic BP
92.0
Heart rate
67.1
15.3
5.4
7.7
148.3
96.0
65.1
15.0
6.1
12.2
−5.4
−4.0
2.0
9.4
4.7
8.0
0.0085
⬍0.001
0.2245
Normotensives
Systolic BP
Diastolic BP
Heart rate
13.0
7.0
8.3
132.8
83.8
69.5
12.5
5.2
10.3
−2.3
−5.6
−1.8
7.1
5.1
9.0
0.1133
⬍0.001
0.3180
130.4
78.3
67.7
visiting a female physician may be less stressful
since patients of either sex with psychological problems are more likely to consult women doctors.10 It
has been shown that during the first three visits BP
decreases, but thereafter no systematic change can
be found.11 Our subjects had their BP measurements
in the health centre performed before the measurements in the hospital. So it seemed that having BP
measured in the hospital was a stronger stimuli in
most subjects than having it measured at the health
centre. Even when repeated in the hypertensives (as
treated) BP remained at a higher level in the hospital. Of course it cannot be excluded that the subject’s
being aware that they should perform an exercise
test at the hospital might be a stress factor, but it
seems unlikely that an exercise test should be more
stressful than to be fitted with an ambulatory BP
monitor, which was the case when they visited the
health centre.
Conclusion
Figure 3 Normotensives. Comparison between BP readings at the
health centre and at the hospital.
study we also found a great intersubject variability.
In our study it was not even necessarily those with
the highest BPs who had the greatest difference
between their office BPs. This, however, does not
exclude the fact that when expressed as a percentage
change from baseline, the variation coefficients are
similar in the different stages of arterial hypertension.7 The reason for the discordance between the
rule and the fact may well be that seeing a doctor or
visiting a hospital is a stronger stimuli in some subjects than in others. The white-coat effect may also
vary from country to country, eg, a study indicates
that American patients find their doctors less exciting than do Italians.8 Systolic BP has also been
found to be significantly greater in female patients
when it is measured by male observers, although
this effect seems to dissipate on repeated measurements.9 There is also evidence that indicates that
Office BP differed significantly between measurements performed at the health centre and at the hospital. Hence, being examined at a hospital seemed
to be a stronger stimuli in most patients than to be
examined in the health centre. When diagnosing or
evaluating treatment in hypertension, this may
have implications.
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