802
Comparison of Probability of Stroke Between
the Copenhagen City Heart Study and
the Framingham Study
Thomas Truelsen, MB; Ewa Lindenstrtfm, MD; Gudrun Boysen, DMSc
Downloaded from http://stroke.ahajournals.org/ by guest on July 12, 2017
Background and Purpose We wished to test the validity of a
stroke probability point system from the Framingham Study
for a sample of the population of Copenhagen, Denmark. In
the Framingham cohort, the regression model of Cox established the effect on stroke of the following factors: age, systolic
blood pressure, the use of antihypertensive therapy, diabetes
mellitus, cigarette smoking, prior cardiovascular disease, atrial
fibrillation, and left ventricular hypertrophy. Derived from this
model, stroke probabilities were computed for each sex based
on a point system. The authors claimed that a physician can
use this system for individual stroke prediction.
Methods The Copenhagen City Heart Study is a prospective survey of 19 698 women and men aged 20 years or older
invited to two cardiovascular examinations at 5-year intervals.
The baseline examination included 3015 men and 3501 women
aged 55 to 84 years; 474 stroke events occurred during 10 years
of follow-up. In both cohorts initial cases of stroke and
transient ischemic attack recorded during 10 years of follow-up
were used. We used the statistical model from the Framingham Study to establish a corresponding stroke probability
point system using data from the Copenhagen City Heart
Study population. We then compared the effects of the relevant risk factors, their combinations, and the corresponding
stroke probabilities. We also assessed stroke events during 10
years of follow-up in several subgroups of the Copenhagen
population with different combinations of risk factors.
Results For the Copenhagen City Heart Study population
some of the risk factors (diabetes mellitus, cigarette smoking,
atrial fibrillation, and left ventricular hypertrophy) had regres-
sion coefficients different from those of the Framingham Study
population. Consequently, the probability of stroke for persons presenting these risk factors and their combinations
varied between the two studies. For some other risk factors
(age, blood pressure, and cardiovascular disease), no major
differences were found. The recorded frequency of stroke
events in subgroups of the Copenhagen population was compatible with the estimated probability intervals of stroke from
the Copenhagen City Heart Study and with those from the
Framingham Study, but these intervals were very large.
Conclusions The majority of risk factors for stroke identified by the Framingham Study also had a significant effect in
the Copenhagen City Heart Study population. The differences
found could be due partly to different definitions of these
factors used by the two studies. Although estimated stroke
probabilities based on point systems from the Copenhagen
City Heart Study and the Framingham Study were similar, the
points scored in the two systems did not always correspond to
the same combination of risk factors. Such systems can be used
for estimating stroke probability in a given population, provided that the statistical confidence limits are known and the
definitions of risk factors are compatible. However, because of
the large statistical uncertainty, a prognostic index should not
be applied for individual prediction unless it is used as an
indicator of high relative risk associated with the simultaneous
presence of several risk factors. (Stroke. 1994;25:802-807.)
I
stroke risk profile was published7 based on the FS
cohort, in which the regression model of Cox was used
to establish the effect on stroke of several risk factors.
Derived from this model, stroke probabilities were
computed for each sex based on a point system. The
authors claimed that a physician can use this system for
individual stroke prediction. We wanted to test the
validity of this point system for the CCHS population.
n Denmark, as well as in the United States, stroke
is the third leading cause of death. Its incidence
has shown no decreasing trend in the last decades.1 The Copenhagen City Heart Study (CCHS),
initiated in 1976, is one of the major prospective cardiovascular surveys in our country permitting studies of
incidence and risk factors of cerebrovascular disease. 26
The effects of risk factors for stroke in our studies were
often discussed with reference to the Framingham
Study (FS), which is considered by us to be a pioneer
cardiovascular survey and is based on a population that
is comparable to ours from racial, demographic, and
socioeconomic perspectives. Recently an article on
Received October 7, 1993; final revision received December 8,
1993; accepted January 10, 1994.
From the Department of Neurology, Hvidovre Hospital, the
Copenhagen City Heart Study (E.L., G.B.), and Copenhagen
University (T.T.), Denmark.
Correspondence to Ewa Lindenstrom, MD, Department of
Neurology, afs 433, Hvidovre Hospital, Kettegard A116 30, 2650
Hvidovre, Denmark.
Key Words • clinical trials
prognosis • risk factors
Denmark • epidemiology
Subjects and Methods
The point system for the prediction of stroke in the FS
cohort was based on 472 initial stroke events that occurred
during 10 years of follow-up in 2372 men and 3362 women. It
used the Cox regression model, relating the chosen risk factors
to stroke risk.7 The stroke probability was calculated as
P= l-[S(t)]B, where S(t) is a survival function for time t and was
determined for 10 years as 0.9044 for men and 0.9353 for
women. B equals e A , where A is a difference between the
mean and individual sum of products of regression coefficients
and corresponding levels of risk factors. The following stroke
types were included: brain infarction, transient ischemic attack, cerebral embolus, and intracerebral and subarachnoid
Truelsen et al
Probability of Stroke
803
TABLE 1. Distribution of Risk Factors for Stroke in Framingham Study and Copenhagen City Heart
Study Populations
FS
CCHS
Risk Factor
Men
Women
Men
Women
Age, y (mean)
65.4
66.1
62.9
62.2
139.3
142.8
145.5
142.7
Diabetes, %
10.6
7.9
3.4
1.6
Smoking, %
33.8
26.4
67.4
51.8
CVD, %
22.2
14.2
15.5
9.1
AF, %
2.8
2.2
1.2
1.0
LVH, %
3.5
2.9
20.6
11.3
16.1
25.0
8.4
11.1
SBP, mm Hg (mean)
HTN Rx, %
FS indicates Framingham Study; CCHS, Copenhagen City Heart Study; SBP, systolic blood pressure; CVD,
cardiovascular disease; AF, atrial fibrillation; LVH, left ventricular hypertrophy; and HTN Rx, antihypertensive therapy.
Downloaded from http://stroke.ahajournals.org/ by guest on July 12, 2017
hemorrhage. We used the statistical model from the FS7 to
develop a corresponding stroke probability point system using
the data from the CCHS population, based on identical
selection of risk factors, ie, age, systolic blood pressure (SBP),
the use of antihypertensive therapy, diabetes mellitus, cigarette smoking, prior cardiovascular disease, atrial fibrillation,
and left ventricular hypertrophy. The risk factors in our
population were defined in the following way: SBP was determined by using a London School of Hygiene sphygmomanometer, with the person in sitting position after 5 minutes of rest.
The blood pressure was determined once. The interobservation variation was tested and found not significant. Current
antihypertensive therapy, current cigarette smoking, and
known diabetes mellitus were included as yes/no variables and
recorded from the questionnaire. Atrial fibrillation and left
ventricular hypertrophy were determined from the electrocardiogram (ECG) using the Minnesota code. Cardiovascular
disease included either earlier myocardial infarction or present angina pectoris or intermittent claudication recorded from
the questionnaire and, for myocardial infarction, also from the
ECG. The stroke subtypes recorded in the CCHS population
were the same as in the FS, except subarachnoid hemorrhage.
Then we compared the effects of these risk factors and their
combinations and the corresponding stroke probabilities between the two studies. We also calculated the stroke events
during 10 years of follow-up in several subgroups of the
Copenhagen population with different combinations of risk
factors.
The CCHS is a prospective survey of 19 698 women and men
aged 20 years or older invited to two cardiovascular examinations at 5-year intervals, in 1976 to 1978 and 1981 to 1983. The
study population, sampling procedures, and classification of
cerebrovascular events were described earlier.12 Cerebrovascular events were recorded until December 31, 1988. For the
present analysis we considered 10-year follow-up from examination 1. The events were recorded at the second examination
and from hospital records and death certificates. At baseline
3015 men and 3501 women aged 55 to 84 years were eligible for
risk factor analysis.
Results
During the 10-year period 474 initial stroke events
occurred in CCHS: 286 in 3015 men and 188 in 3501
women. The mean values for the selected risk factors
from the CCHS and the FS populations are shown in
Table 1. The corresponding regression coefficients are
shown in Table 2. In this subset of the CCHS population
the effects of atrial fibrillation (/><.93) or cigarette
smoking (P<.17) in men and the effect of left ventric-
ular hypertrophy (P<.99) in women were not statistically significant. In the FS these three risk factors had
significant effects, and a significant interaction between
SBP and antihypertensive therapy was found in women,
whereas in the CCHS there was no significant interaction in either sex.
Based on the regression coefficients shown in Table 2,
we created a point system and calculated the corresponding probabilities for developing stroke or transient
ischemic attack during a 10-year period. The function
S(t) for t=10 years was 0.946 for women and 0.905 for
men. The M function (sum of products of regression
coefficients and frequencies of risk factors in the CCHS
population; Tables 1 and 2) was 5.7046 for women and
6.8122 for men. Stroke probability for men and women
and corresponding relative risks (RR) are shown in
Tables 3 and 4, respectively.
It can be seen that the regression coefficients varied
between the two systems, particularly for diabetes,
smoking, left ventricular hypertrophy, and atrial fibrillation. Consequently, the corresponding points and
probabilities of developing stroke varied for combinations including these risk factors,7 which can also be
seen from the four following examples. For each of
these examples, only the chosen risk factors were present; all the other factors were absent.
Example 1: A 65-year-old man with an SBP of 165
mm Hg who has diabetes, left ventricular hypertrophy,
cardiovascular disease, and atrial fibrillation and receives antihypertensive therapy. According to the
CCHS he scores 28 points, and his 10-year probability
of developing stroke is 68.3% (95% confidence interval
[CI], 0% to 86%). According to the FS he scores 26
points, and his 10-year probability of developing stroke
is 68.4%.
Example 2: A 65-year-old man with an SBP of 165
mm Hg who has atrial fibrillation and left ventricular
hypertrophy. According to the CCHS he scores 14
points, and his 10-year probability of developing stroke
is 15.0% (95% CI, 0% to 27%). According to the FS he
scores 19 points, and his 10-year probability of developing stroke is 32.9%.
Example 3: A 71-year-old woman with an SBP of 145
mm Hg who smokes and has cardiovascular disease.
According to the CCHS she scores 15 points, and her
804
Stroke Vol 25, No 4 April 1994
TABLE 2. Cox Regression Coefficients for Stroke Risk Factors in the Framingham Study
and the Copenhagen City Heart Study
FS
CCHS (SE)
Risk Factor
Men
Women
Age
.0505
.0657
SBP
HTNRx
SBP * HTN Rx
Diabetes
Smoking
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CVD
AF
.0140
.3263
.0
.3384
.5147
.5195
.6061
.0197
2.5432
-.0134
.5442
.5294
.4326
1.1497
Men
Women
.06977
.04900
(.00949)
(.01187)
.01433
.01660
(.00252)
(.00302)
.50267
.43321
(.16772)
(.18420)
.0
.0
(0)
(.0)
.79161
1.19602
(.22420)
(.32962)
.17598
.30620
(.12632)
(.14999)
.53374
.45635
(.14549)
(.20681)
.05359
2.07702
(.50749)
LVH
.8415
.8488
.27856
(.32295)
-.00111
(.13617)
(.21067)
FS indicates Framingham Study; CCHS, Copenhagen City Heart Study; SBP, systolic blood
pressure; HTN Rx, antihypertensive therapy; SBP * HTN Rx, interaction between SBP and HTN Rx;
CVD, cardiovascular disease; AF, atrial fibrillation; and LVH, left ventricular hypertrophy.
10-year probability of developing stroke is 11.8% (95%
CI, 6.3% to 16.4%). According to the FS she scores 15
points, and her 10-year probability of developing stroke
is 16.0%.
Example 4: A 71-year-old woman with an SBP of 145
mm Hg who has atrial fibrillation and cardiovascular
disease. According to the CCHS she scores 27 points,
and her 10-year probability of developing stroke is
51.9% (95% CI, 19.6% to 70.3%). According to the FS
she scores 18 points, and her 10-year probability of
developing stroke is 27.0%.
The examples above show how the values of the
prognostic index varied between the two studies, depending on the risk factors included. To control the
validity of the prognostic indexes from the two studies,
we selected four subgroups of the CCHS population
with different combinations of risk factors and assessed
the stroke events that occurred during a 10-year followup. Then we compared the true stroke frequencies with
corresponding estimated probabilities based on t h e
point systems from the two studies. In the following four
groups only the chosen factors were present.
Group A comprised men aged 63 to 68 years with SBP
between 140 and 160 mm Hg who were smokers. In the
CCHS cohort 135 men complied with these criteria; 14
(10.4%) developed stroke or transient ischemic attack
during the 10-year period. The corresponding estimated
probabilities of stroke would be 7.8% to 13.2% (9 to 13
points) according to the CCHS and 9.7% to 12.9% (10
to 12 points) according to the FS.
Group B comprised men aged 63 to 70 years with SBP
between 140 and 170 mm Hg who were smokers and had
left ventricular hypertrophy. In the CCHS cohort, 4 of
46 eligible men (8.7%) developed stroke in 10 years.
The corresponding estimated probabilities of stroke
would be 10.2% to 21.9% (11 to 17 points) according to
the CCHS and 14.8% to 25.5% (13 to 17 points)
according to the FS.
Group C comprised women aged 55 to 74 years with
SBP between 95 and 200 mm Hg who were smokers and
had left ventricular hypertrophy. In the CCHS cohort, 6
of 140 eligible women (4.3%) developed stroke in 10
years. The corresponding estimated probabilities of
stroke would be 1.8% to 20.2% (2 to 19 points) according to the CCHS and 3.5% to 57.0% (7 to 23 points)
according to the FS.
Group D comprised women aged 63 to 70 years with
SBP between 140 and 170 mm Hg who were smokers
and were receiving antihypertensive therapy. In the
CCHS cohort, 3 of 29 eligible women (10.3%) developed stroke in 10 years. The corresponding estimated
probabilities of stroke would be 7.8% to 17.7% (12 to 18
points) according to the CCHS and 9.2% to 22.8% (12
to 17 points) according to the FS.
Discussion
Although detailed analysis of the CCHS and FS
populations was not the subject of this article, there
seemed to be no major differences concerning their
composition, and both samples have approximately the
same size. However, the regression coefficients for
Truelsen et al Probability of Stroke
TABLE 3.
805
Probability of Initial Stroke/TIA for Men Aged 55-84 Years Based on the Copenhagen City Heart Study
Points
0
1
2
3
4
5
57-58
59-60
61-62
63-64
65-66
7
69-70
9
55-56
6
67-68
8
Age, y
Risk Factor
71-72
73-74
SBP, mm Hg
95-104
105-114
115-124
125-134
135-144
145-154
155-164
165-174
175-184
185-194
AF
No/Yes
Smoking
No
LVH
No
Yes
Yes
HTN Rx
No
Yes
CVD
No
Yes
Diabetes
No
Yes
Probability of Developing Stroke for Men Within a 10-Year Period
Points
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Prob, %
(RR)
Points
Prob, %
(RR)
Points
Prob, %
(RR)
1
2.6
(1.2)
11
10.2
(4.7)
21
35.1
(18.9)
2
3.0
(1.3)
12
11.6
(5.4)
22
39.2
(21.8)
3
3.4
(1.5)
13
13.2
(6.2)
23
43.5
(25.0)
24
4
4.0
(1.8)
14
15.0
(7.1)
48.2
(28.8)
5
4.5
(2.0)
15
17.1
(8.2)
25
53.0
(33.1)
6
5.2
(2.3)
16
19.4
(9.4)
26
58.0
(38.1)
7
5.9
(2.7)
17
21.9
(10.8)
27
63.1
(43.8)
8
6.8
(3.1)
18
24.7
(12.4)
28
68.3
(50.4)
9
7.8
(3.5)
19
27.9
(14.3)
29
73.3
(58.0)
10
8.9
(4.1)
20
31.3
(16.4)
30
78.1
(66.7)
SBP indicates systolic blood pressure; AF, atrial fibrillation; LVH, left ventricular hypertrophy; HTN Rx, antihypertensive therapy; CVD,
cardiovascular disease; Prob, estimated probability of stroke within 10 years; and RR, relative risk.
In upper table, to calculate total amount of points, the points corresponding to each risk factor present should be added; eg, a man
70 years old who smokes and has diabetes and an SBP of 165 mm Hg scores 7 + 1 + 6 + 7 , ie, 21 points.
In lower table, the average RR for men aged 55-84 years in the Copenhagen City Heart Study was 2.7.
antihypertensive therapy in women, cigarette smokers,
and those with diabetes, atrial fibrillation, and left
ventricular hypertrophy were very different in the two
studies (Table 2). In the FS population diabetes was
nearly three times as frequent as in ours (Table 1). At
the same time we found a much higher regression
coefficient for diabetes than did the FS. The explanation
for these discrepancies could be that we denned this
factor as self-reported diabetes, recorded from the
questionnaire, whereas the FS definition of diabetes
included casual blood glucose of 150 mg/100 mL or
more at the two biennial examinations or history of
abnormal glucose tolerance test or treatment for diabetes.8 Consequently, the number of persons with mild
and borderline diabetes may be underestimated in our
study, thereby explaining the relatively important effect
of this disease on stroke risk in our population.
Cigarette smoking had a greater effect on stroke risk
in the FS population than in ours. Moreover, in our
study this effect was not significant in men in the chosen
age group. We had previously reported that smoking
was a significant risk factor for stroke in the population
aged 35 years and older, but its effect decreased with
age.5 The proportions of smokers were also very different: 33.8% and 26.4% in the FS and 67.4% and 51.8%
in the CCHS for men and women, respectively (Table
1). Possible differences in smoking habits, such as
quantity of cigarettes and inhaling, might also influence
the effect of smoking on stroke, but these data were not
included in the present analysis.
In both populations atrial fibrillation was associated
with elevated stroke risk, and this effect was greater in
women than in men. In contrast, the corresponding
regression coefficients in our population were nearly
two times higher in women and eight times lower (and
not significant) in men than in the FS population. The
proportions of men and women with atrial fibrillation
were two times higher in the FS population. Paroxysmal
atrial fibrillation was not likely to be diagnosed during
one ECG recording in the CCHS, whereas ECGs from
two biennial examinations in the FS might include a
greater proportion of this condition. The effect of atrial
fibrillation on stroke was also assessed in other prospective studies. The Whitehall Study, based on a cohort of
19 018 men aged 40 to 69 years, found atrial fibrillation
in 2.4% of patients, with the RR of stroke associated
with this condition being 6.9 (CI, 3.0 to 13.5).9 In the
British Regional Heart Study, based on 7727 men, the
frequency of atrial fibrillation was 0.6% and the RR 2.3
(95% CI, 0.1 to 12.7).10 Both the proportion and effects
of atrial fibrillation vary a great deal from one study to
another, probably because of the low prevalence of this
806
Stroke Vol 25, No 4 April 1994
TABLE 4. Probability of Initial Stroke/Transient Ischemic Attack for Women Aged 55-84 Years Based on the
Copenhagen City Heart Study
Points
Risk Factor
0
1
4
3
2
5
7
6
8
9
Age, y
55-57
58-60
61-63
64-66
67-69
70-72
73-75
76-78
79-81
82-84
SBP, mm Hg
95-103
104-112
113-121
122-130
131-139
140-148
149-157
158-166
167-175
176-184
LVH
No/Yes
Smoking
No
14
Yes
HTNRx
No
Yes
CVD
No
Yes
Diabetes
No
AF
No
Yes
Yes
Probability of Developing Stroke for Women Within a 10-Year Period
Prob, %
(RR)
Points
Prob, %
(RR)
Points
Prob, %
1.6
(1.2)
11
6.7
(5.8)
21
26.1
(28.5)
2
1.8
(1.4)
12
7.8
(6.7)
22
29.6
(33.1)
3
2.1
(1.6)
13
8.9
(7.8)
23
33.4
(42.5)
(9.0)
24
37.5
(49.4)
Points
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1
(RR)
4
2.5
(1.8)
14
5
2.8
(2.1)
15
11.8
(10.5)
25
42.0
(57.4)
(12,2)
26
46.8
(66.7)
10.3
6
3.3
(2.5)
16
13.5
7
3.8
(2.9)
17
15.5
(15.6)
27
51.9
(77.5)
8
4.4
(3.3)
18
17.7
(18.2)
28
57.2
(90.0)
9
5.1
(3.9)
19
20.2
(21.1)
29
62.5
(115.6)
10
5.8
(4.5)
20
23.0
(24.5)
30
67.9
(134.3)
SBP indicates systolic blood pressure; LVH, left ventricular hypertrophy; HTN Rx, antihypertensive therapy; CVD, cardiovascular
disease; AF, atrial fibrillation; Prob, estimated probability of stroke within 10 years; and RR, relative risk.
In upper table, to calculate total amount of points, the points corresponding to each risk factor present should be added; eg, a woman
70 years old who smokes and has diabetes and an SBP of 165 mm Hg scores 5 + 2 + 8 + 7 , ie, 22 points.
In lower table, the average RR for women aged 55-84 years in the Copenhagen City Heart Study was 2.5.
condition. In our study four of the 33 men with atrial
fibrillation developed subsequent stroke. Statistical
analyses based on so few cases often give inconclusive
results. Left ventricular hypertrophy was diagnosed
from the ECG in both studies. However, in the CCHS
its definition was based only on R and S wave potentials,
whereas in the FS it required the simultaneous presence
of a depressed ST segment or flattened to inverted T
waves. Thus, the definition in the FS was more restrictive and selected persons with more severe left ventricular hypertrophy than our definition, which explains
why this condition was nearly six times more frequent in
the CCHS than in the FS population and why its effect
on stroke risk was much smaller in the CCHS than in
the FS population. Thus, despite a lack of apparent
social, racial, and demographic differences, both the
distribution and the effect of several stroke risk factors
varied between these two populations. The majority of
these differences might be explained by discrepancies in
definitions of risk factors. The prognostic index based
on combinations of these risk factors varied correspondingly, so that the point system established in the FS
could not be directly applied to our population, which
we also have illustrated in some examples of risk factor
combinations. In examples 2 and 4 the estimated prob-
ability of stroke based on the FS was different from
ours, and in example 2 it was outside our 95% CI.
However, in examples 1 and 3 the stroke probability was
similar.
We found that the real frequencies of stroke events
assessed in four subgroups of the CCHS cohort (A
through D) were compatible with the corresponding
estimated probability intervals based on the CCHS and
with those based on the FS. However, these intervals
were so large that they would hide even quite large
discrepancies between the estimated stroke probabilities and the observed stroke frequencies.
The issue of statistical uncertainty was not discussed
by FS authors,7 and the SE corresponding to the different regression coefficient was not presented. Our experience shows that the SE values can be quite large, even
for significant risk factors (Table 2). Consequently, the
probability of stroke for persons presenting different
combinations of risk factors will be subject to great
uncertainty, as shown in examples 1 through 4. In
example 1 the probability of developing stroke during
10 years was 68.3%, but the 95% CI was 0% to 86%. For
that reason a prognostic index would have no great
validity for individual prediction unless it is used only as
an indicator of high relative risk for persons with
Truelsen et al Probability of Stroke
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combinations of several risk factors. However, the latter
possibility should also be interpreted with caution.
Although the information that one's risk is several times
higher than average may motivate the patient to attempt
reasonable risk factor modification, the risk reduction
obtained cannot be derived directly from the stroke
probability table. Cessation of smoking might not automatically reduce the stroke risk to the level of nonsmokers, and it is reasonable to suppose that, during a certain
time at least, being a previous smoker will be associated
with somewhat higher stroke risk than being a nonsmoker. The stroke probability system could, on the
other hand, be used for stroke prediction in a given
population if the CIs are known and provided that the
patient population is representative of the population
for which the point system has been established. A
practitioner knowing the distribution of risk factors
discussed above in his patient population could, according to such a point system, predict how many events will
occur in this population during, for example, 10 years.
Of course, it is of paramount importance that the risk
factor definitions used by a practitioner be compatible
with those used to establish the point system.
In summary, the majority of risk factors for stroke
identified by the FS also had a significant effect in the
CCHS population, with the differences partly due to
different definitions. However, the results of this analysis illustrate a basic problem of the epidemiologic
method. On the basis of observation in one population
it can be possible, to some extent, to predict events in a
comparable population but not in a single individual.
Ack nowledgments
This study was supported by health insurance funds No.
11/272-90 and No. 11/203-92; the Danish Medical Research
807
Council (No. 12-0807-1); the Foundation of Henry Hansen,
member of the Stock Exchange, and his wife Karla Hansen,
nee Westergaard; and the Danish Heart Foundation. We are
indebted to the statistician Jorgen Nyboe, MSc, and to Gorm
Jensen, DMSc, and Peter Schnohr, MD, who, together with
J0rgen Nyboe and Merete Appleyard, RTL, chief secretary of
the CCHS, initiated and conducted the CCHS. We also thank
Merete Appleyard for her assistance with data processing.
References
1. Lindenstrom E, Boysen G, Nyboe J, Appleyard M. Incidence rates
of stroke in Copenhagen, 1976-1988. Stroke. 1992;23:28-32.
2. Appleyard M, ed. The Copenhagen City Heart Study: Osterbroundersogelsen: a book of tables with data from the first examination (1976-78) and a five year follow-up (1981-83). Scand J Soc
Med. 1989;170(suppl 41):l-160.
3. Boysen G, Nyboe J, Appleyard M, Soelberg Sorensen P, Boas J,
Sommier F, Jensen G, Schnohr P. Stroke incidence and risk factors
for stroke in Copenhagen. Stroke. 1988;19:1345-1353.
4. Lindenstrom E, Boysen G, Nyboe J. Life-style factors and stroke
risk, I: basic demographic and social factors. Neuroepidemiology.
1993;12:37-42.
5. Lindenstrom E, Boysen G, Nyboe J. Life-style factors and stroke
risk, II: life-style factors. Neuroepidemiology. 1993;12:43-50.
6. Lindenstrom E, Boysen G, Nyboe J. Lifestyle factors and risk of
cerebrovascular disease in women: the Copenhagen City Heart
Study. Stroke. 1993;24:1468-1472.
7. Wolf PA, D'Agostino RB, Belanger AJ, Kannel WB. Probability of
stroke: a risk profile from the Framingham Study. Stroke. 1991 ;22:
312-318.
8. Shurtleff D. Some characteristics related to the incidence of cardiovascular disease and death: Framingham Study 18-year
follow-up. In: Kannel WB, Gordon T, eds. The Framingham Study:
Section 30. Washington, DC: US Government Printing Office;
1974. US Dept of Health, Education, and Welfare publication NIH
74-599.
9. Reid DD, Brett GZ, Hamilton PJS, Jarrett RJ, Keen H, Rose G.
Cardiorespiratory disease and diabetes among middle-aged male
civil servants. Lancet. 1974;l:469-473.
10. Rose G, Baxter PJ, Reid DD, McCartney P. Prevalence and
prognosis of electrocardiographic findings in middle-aged men. Br
Heart J. 1978;40:636-643.
Comparison of probability of stroke between the Copenhagen City Heart Study and the
Framingham Study.
T Truelsen, E Lindenstrøm and G Boysen
Stroke. 1994;25:802-807
doi: 10.1161/01.STR.25.4.802
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