Venous Thromboembolism and Other Venous Disease
in the Tecumseh Community Health Study
By WILLIAM W. COON, M.D., PARK W. WILLIS, III, M.D., AND JACOB B. KELLER, M.P.H.
SUMMARY
The prevalence and incidence of venous thromboembolism and other venous disease has been
determined as part of a longitudinal study of health and disease in a Michigan community. When
these data are extrapolated to 1970 U.S. census figures, a rough estimate of annual incidence of
clinically recognized deep venous fhrombosis is over 250,000 cases while that of superficial thrombophlebitis is over 123,000. An estimated 24 million US citizens have "significant" varicose veins
while 6 to 7 million have stasis changes in the skin of the legs and 400,000 to 500,000 have or have
had a varicose ulcer. The relatively high frequency of these conditions in the adult population of
Tecumseh, Michigan, indicates that they represent several of the more common medical problems
encountered by the practicing physician.
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Additional Indexing Words:
Epidemiology
Venous disease
Pulmonary embolism
Thrombophlebitis
LITTLE INFORMATION is available concerning
the frequency of development and prevalence
of venous thromboembolism and other interrelated
venous conditions in the US population. Published
estimates have been derived from data obtained
from diagnoses of hospitalized patients. While
figures extracted from a hospital population may
provide a reasonable estimate of the frequency of
recognized fatal pulmonary embolism, they probably represent a gross underestimate of the
prevalence of deep and superficial venous thrombosis and nonfatal pulmonary embolism and provide
no reliable approximation of the frequency of
varicose veins, stasis skin changes, or varicose
ulcers. The Tecumseh Community Health Study
has provided the milieu required to determine the
frequency of appearance of these conditions in a
segment of the US population.
Varicose veins
Methods
The Tecumseh Community Health Study (TCHS) is
a longitudinal study of a total community, initiated in
1957 to determine epidemiological factors influencing
health and disease in Tecumseh, a city in southeastern
Michigan.1 2 The community under study includes both
the town and its surrounding rural area. During
1959-1960 88% (8,641 persons) of the total population
of all ages participated in the first cycle of clinical
examinations involving complete medical history, physical examination, and various laboratory tests. In
1962-1965 residents of Tecumseh, as well as persons
examined in the first cycle who had moved to nearby
areas, were again invited to participate in a second
similar series of examinations. The second phase of the
study (TCHS II) included 9,226 persons. A third cycle
of examinations was carried out in 1967-1969 in 6,012
persons (TCHS III). During TCHS II and III
questions were added to the medical questionnaire
specifically regarding a prior history of phlebitis and
related conditions. At TCHS II supplemental questions
regarding dates of occurrence, precipitating events,
symptoms, and treatment were asked of those persons
reporting a history of phlebitis or "leg vein clot." This
supplemental information covered all such conditions
regardless of when they occurred. In addition, the
original medical interview contained questions concerning pain in the legs or chest, shortness of breath,
hemoptysis, and leg swelling. Physical examinations
were performed by physicians from the teaching staff of
the University of Michigan Medical School and the
TCHS medical staff.
Except for the history of varicose ulcer which had
subsequently healed, the diagnoses of varicose veins,
stasis skin change, and active varicose ulcer were made
from data recorded at physical examination (TCHS
From the Departments of Surgery, Medicine (Division of
Cardiology) and Epidemiology and the Center for Research
in Diseases of the Heart, Circulation and Related Disorders,
University of Michigan, Ann Arbor, Michigan.
Supported by a Program Project Grant (HL 09814) from
the National Heart and Lung Institute, National Institutes of
Health, Bethesda, Maryland, and by the Michigan Heart
Association.
Address for reprints: William W. Coon, M. D., Department of Surgery, University of Michigan Medical Center,
1405 East Ann Street, Ann Arbor, Michigan 48104.
Received April 30, 1973; revision accepted for publication
June 4, 1973.
Circulation, Volume XLVIII, October 1973
Venous thrombosis
839
840
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II). Varicose veins were detected by examination in the
standing position and were coded as to relative severity
as 1, 2, 3+. The other physical findings pertinent to
this study were edema, stasis changes in the skin of the
legs, an active varicose ulcer, or the scar of a healed
ulcer adjacent to the medial malleolus. All diagnoses
were separately reviewed by a TCHS senior physician
before final coding.
In the course of this analysis records of all subjects
with a diagnosis of venous thromboembolism or other
pertinent venous disease (varicose ulcer, stasis dermatitis) or with evidence by physical examination of
unilateral or asymmetrical bilateral edema or varicose
veins were individually reviewed. From this review the
study group was defined. The great majority of cases of
venous thrombosis and pulmonary embolism was
identified on the basis of a report by the subject that
such a diagnosis had been made at the time of the
episode by his personal physician. Additional episodes,
found during review of records, were included only if
they met the following criteria: 1) pulmonary embolism: sudden onset of dyspnea and pleuritic chest pain
or hemoptysis in conjunction with an event (trauma,
operation, etc.) known to be associated with a high
frequency of development of pulmonary embolism;
fever minimal or absent; 2) deep venous thrombosis of
the leg: pain or tenderness and edema of the leg which
necessitated bed rest or anticoagulant therapy; in
addition, included in this group were subjects who were
found at physical examination to have evidence of
postphlebitic sequelae which historically developed
shortly after an operation or leg trauma; these instances
of "cryptic venous thrombosis" represent 11% of the
total number of diagnoses of deep venous thrombosis;
3) superficial venous thrombosis: palpable subcutaneous cord and/or increased heat restricted to a limited
area of the leg or thigh and not accompanied by
significant edema or followed by postphlebitic sequelae.
The diagnosis of stasis skin change was retained only if
the examining physician recorded the presence of
increased pigmentation, fibrosis, induration, or atrophy
of skin at or adjacent to the medial malleolus.
Because of the greater detail of the questionnaire in
the second series of examinations, the population seen
at that time is used as the base for most of the analyses
described in this report. However, for incidence
analyses, persons seen at any pair of examinations are
included since it was felt that the questions at the
second and third examination would identify those
persons who had experienced an event prior to the first
examination. For persons who participated in all three
examination series, the interval from the first to the third
examination is used. Subjects less than ten years old are
excluded from all analyses because no children in this
category were found to have venous thromboembolism
or other venous disease.
Thromboembolic events which occurred prior to the
second series of examinations are used to calculate
several sets of rates. Events are classified into age
ranges according to age at occurrence. Person-years at
risk for developing disease are calculated for each age
range by assigning one person-year to the appropriate
ranges for each year an individual has lived. Risk of
COON, WILLIS, KELLER
developing disease
relating number of
is assessed
retrospectively by
events in an age range to the
number of person-years at risk. This analysis is referred
to in the tables as "thromboembolic events by age at
occurrence." Rates are expressed as number of events
per 10,000 persons per year. In the calculation of rates
for first events, persons who have had an event are
removed from risk at that time and subsequent events
are not counted. When calculating rates for all events,
they are not removed from risk and all events are
counted.
Risk of a thromboembolic event during pregnancy or
in the postpartum period is also evaluated. Events
which occurred during or after pregnancy are classified
by age at termination of pregnancy and related agespecifically to the total number of pregnancies.
The number of individuals who have experienced an
event, classified by age at examination, is related agespecifically to the number of people examined. This
measure is called cumulative prevalence.
Results
Tables 1 and 2 record data concerning "first" and
C"all" venous thromboembolic events by sex and age
at the time of the event for persons examined in the
second examination series. The category of pulmonary embolism includes individuals with or without
accompanying signs of deep venous thrombosis.
The group with deep venous thrombosis includes
only those persons without symptoms or signs of
pulmonary embolism. Here and in table 3 the true
frequency of superficial thrombophlebitis is probably much higher than that recorded since many
episodes of this relatively minor problem may have
been forgotten by the subjects.
The higher frequency of deep venous thrombosis
and pulmonary embolism in young women can be
attributed, in part, to the added risks of thromboembolism during pregnancy and the puerperium.
One half of first events (46 of 89) in women below
age 40 were associated with pregnancy. Table 3
presents an estimate of the frequency of venous
thrombosis in relation to pregnancy and the
postpartum period. Since only three episodes of
pulmonary embolism were diagnosed, these events
are incorporated in the rates for deep thrombosis.
An event was recognized once in approximately
every 200 pregnancies. Although there is an
apparent increase in rate of deep venous thrombosis
with increasing age, the differences are not
statistically significant; a larger sample might have
shown a valid difference since Inman and Vessey3
have reported a higher rate of puerperal thromboembolic deaths in women aged 35-44 as compared
to younger women. When separate rates were calculated for ordinal number of pregnancy, no inCirculation, Volume XLVIII, October 1973
VENOUS DISEASE IN A MICHIGAN COMMUNITY
841
Table 1
First Thromboembolic Events by Age at Occurrence, Sex, and Type of Event
Sex
Males
Females
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crease
Age
at
occurrence
Personyears
at risk
10-19
20-29
30-39
4049
50-59
60-69
70-79
80-89
27,127
20,313
14,902
8,635
4,449
1,827
550
72
10-19
20-29
30-39
40-49
50-59
60-69
70-79
80-89
29,943
22,503
15,800
9,206
5,068
2,507
897
169
Pulmonary
embolism
No. per
10,000
per year
No.
0
1
2
0
0.5
1.3
2.3
4.5
0
0
0
2
2
0
0
0
2
5
3
3
3
0.7
2.2
1.9
3.3
5.9
4.0
11.1
0
1
1
0
Deep venous
thrombosis
No. per
10,000
per year
No.
0
3
2
11
6
5
1
0
7
41
31
20
10
5
1
1
0
1.5
1.3
12.7
13.5
27.3
18.2
0
2.3
18.2
19.6
21.7
19.7
19.9
11.1
59.2
Superficial
venous thrombosis
No. per
10,000
per year
No.
1
0
0.4
0.5
1.3
6.9
4.5
16.4
18.2
0
0
7
8
7
3
3
2
0
0
3.1
5.1
7.6
5.9
12.0
22.3
0
1
1
2
6
2
3
be either deep venous thrombosis or pulmonary
embolism are included. As one might expect, the
risk of recurrence is many times higher than the risk
of a first event. A recurrence was recognized about
once in every 11 to once in every 50 persons per
year, depending on age and sex. The rates of
recurrence of superficial venous thrombosis (not
shown in the table) were 89 (female) to 90 (male)
in rate with increasing number of preg-
nancies could be demonstrated.
Table 4 lists the number of recurrent thromboembolic events; rates of recurrence are calculated for
those individuals having a known prior deep venous
thrombosis or pulmonary embolism. The size of the
sample did not permit a more extensive breakdown
by age. All recurrent events which were thought to
Table 2
All Thromboembolic Events by Age At Occurrence, Sex, and Type of Event
Pulmonary
embolism
Age
Sex
Males
at
occurrence
10-19
20-29
30-39
4049
50-59
60-69
70-79
Females
Personyears
at risk
27,139
20,356
14,986
No.
0
0
0
1
2
2
3
2
1.5
1.3
13
14.8
1,929
601
2
2
0
0
80-89
82
0
0
10-19
29,974
22,803
2
0.7
3.1
3.7
5.2
20-29
30-39
40-49
50 59
60-69
70-79
80-89
4,547
16,384
9,692
5,450
2,692
988
174
Circulation, Volame XLVIII, October 1973
No.
venous
No. per
10,000
per year
0
0.5
1.3
2.3
4.4
10.4
8,769
Superficial
Deep venous
thrombosis
No. per
10,000
per year
7
6
5
6
11.0
1
1
10.1
0
0
3.7
No.
1
1
10
22.0
8
3
2
41.5
49.9
3
7
5
3
2
243.9
0
7
43
46
30
20
6
1
1
2.3
18.9
28.1
31.0
36.7
22.3
thrombosis
No. per
10,000
per year
0.4
0.5
2.0
8.0
11.0
15.6
33.3
0
0
0
9
3.9
7.9
13.4
14.7
10.1
13
13
8
12
2
20.2
57.5
0
0
44.6
COON, WILLIS, KELLER
842
Table 3
All Thromboembolic Events During or After Pregnancy by Age at Termination of Pregnancy
and Type of Event
Pulmonary embolism or
deep venous thrombosis
Age
at termination
of pregnancy
1000
pregnancies
No.
preg.
711
4
11
5.6
3.7
6.9
7.8
9.2
7.3
5.9
16-19
20-24
25-29
30-34
35-39
4044
2936
2322
1284
542
137
7932
Total
10,000 persons per year for those age 45 or
under and 150 (male) to 191 (female) for those
over age 45.
Tables 5 and 6 show the incidence of first and
recurrent thromboembolic events between examinations. For most respondents this is the interval
between the first and third examination series, but
for some the interval is first to second or second to
third examination. The rates presented are computed on the basis of person-years at risk between
examinations. The number of affected individuals
was insufficient to calculate risk by ten-year age
groups. When comparable rates from the retrospective data (tables 1, 2, and 4) are compared with
those from the estimates of incidence (tables 5 and
6), the incidence figures are somewhat higher. This
difference would be expected if one assumes that
some events in the past may have been forgotten. If
this assumption is true, the higher estimates of risk
from the incidence tables may be closer to actual.
Three subjects interviewed and examined at
TCHS II who subsequently died had a clinical
diagnosis of pulmonary embolism as the cause of
death; autopsy was performed in one of these
individuals and confirmed the diagnosis.
Table 7 records the cumulative prevalence of
venous thromboembolism and the prevalence of
per
Superficial
venous
No. per
Number
of
16
10
5
1
47
thrombosis
No. per
1000
No.
preg.
0
0
1
5
0.3
2.2
1
0.8
0
0
0
0
7
0.9
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other vein-related disease for persons examined in
the second examination series. The group with "no
venous disease" is the segment of the population
who by history and physical examination had none
of the listed conditions. The diagnosis of "any
varicose veins" included all subjects in whom
prominent superficial veins were noted in the lower
extremities at either the first or second examination.
In order to separate from this all-inclusive category
those individuals with varicosities which might be
of greater clinical significance, the frequency of
varicose veins recorded as 2+ or greater (moderate
or severe) is listed separately. Only two of the 13
individuals with historical or physical evidence of a
varicose ulcer had an active ulcer at the time of
examinations. Approximately 10% of men and 20% of
women with varicose veins had evidence of edema
at physical examination. The frequency of edema
was somewhat higher in the group with 2+ or
greater varicose veins (16%) when compared to the
sample with 1+ varicose veins (9%). Edema was
present in about 1/5 of males and 1/3 of females
with stasis changes in the skin of the legs.
Prevalence of varicose veins and stasis skin
changes was calculated for women age 40 and over
in relation to number of pregnancies experienced
(0, 1,
7, 8+). The results are not shown.
.
.
.
Table 4
Recurrence of Deep Venous Thrombosis and Pulmonary Embolism Among Persons with a
Prior Event by Age at Recurrence and Sex
Age
at
recurrence
Personyears
at risk
No.
Males
under 46
46 or older
Females
under 46
46 or older
431
158
2184
463
9
14
74
22
Sex
No. per
10,000
per year
209
886
339
475
Circulation, Volume XLVIII, October 1973
VENOUS DISEASE IN A MICHIGAN COMMUNITY
843
Table 5
Incidence of First Events Among Persons Free of Thromboembolic Disease at Initial Examination, By Age
at Initial Examination, Sex, and Type of Event
Pulmonary
embolism
Sex
Males
Females
Deep venous
thrombosis
Age
at
occurrence
Personyears
at risk
No.
per year
No.
No. per
10,000
per year
under 46
46 or older
under 46
46 or older
20,582
4,104
21,606
4,468
3
3
3
3
1.5
7.3
1.4
6.7
9
9
32
12
4.4
21.9
14.8
26.9
No per
10,000
Although
we had presumed that the frequency of
appearance of these conditions might increase
with increasing number of pregnancies, no signifidifferences were found.
The presence of varicose veins or other possible
postphlebitic sequelae (edema, stasis changes,
varicose ulcer) was separately assessed in the 151
subjects with a diagnosis of deep venous thrombosis
or pulmonary embolism. Thirty-six (24%) had
edema; in three, edema was the only finding.
Varicose veins were present in 103 (68%) and were
the only condition present (except for edema in
some) in 74. Twenty-seven subjects (18%) had
stasis changes. Four had an active or healed
varicose ulcer. Only 43 (28%) were free of any of
these "vein-related" conditions.
cant
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Discussion
Any epidemiologic study of venous thromboembolism based upon detection of disease by medical
history and physical examination will result in a
gross underestimate of the actual frequency of
disease. Determinations of the prevalence of
pulmonary embolism at necropsy4 and of deep
venous thrombosis by radio-iodinated fibrinogen=)
have shown that only a fraction of the total number
of cases has been recognized by clinical means
alone.
A sample of the size with which we were dealing
is insufficient to assess the frequency of fatal
Superficial
venous thrombosis
No. per
10,000
No.
per year
6
6
12
3
pulmonary embolism. Although estimates of the
number of deaths due to pulmonary embolism in
the United States which have been based upon
extrapolations from a sample of hospitalized patients are not derived from a representative sample,
these are the only figures available. If estimates of
death from pulmonary embolism include both those
cases
cause
in which pulmonary embolism was the sole
of death and those in which it was major
contributory cause, both Coon and Willis6 and
Hume, Sevitt, and Thomas7 arrive at a figure
between 142,000 and approximately 200,000 deaths
per year. For every fatality from pulmonary
embolism, there are at least two to six nonfatal
pulmonary embolic events of clinical significance.
On the other hand, the data derived from this
study are of value as an estimate of the medical
impact of clinically significant superficial and deep
venous thromboses. The long-term disability which
may result from deep venous thrombosis of the
lower extremities usually follows only those venous
thrombi which extend to involve femoral and iliac
veins. Thrombotic obstruction of the deep veins of
this extent is frequently accompanied by clinical
manifestations recognized by patient or physician
such as edema, pain, tenderness, and increased local
heat.
An unresolved question is what proportion of the
somewhat nonspecific skin changes of the lower
extremities should be attributed to a previously
Table 6
Incidence of Recurrent Episodes of Deep Venous Thrombosis or Pulmonary Embolism Among
Persons Having Experienced Such An Event Prior to Initial Examination, by Age at Initial
Examination and Sex
Age
Sex
Males
Females
at
Personyears
No. per
10,000
examination
at risk
No.
per year
under 46
46 or older
under 46
46 or older
67
170
491
421
2
19
46
38
299
1118
937
903
Circ;uation, Volume XLVIII. October 1973
2.9
14.6
5.6
6.7
COON, WILLIS, KELLER
844
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Circulation, Volume XLVIII, October 1973
VENOUS DISEASE IN A MICHIGAN COMMUNITY
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unrecognized thrombotic occlusion of the deep
veins which has produced venous valvular incompetence. Some individuals may have developed
stasis changes secondary to prolonged venous
insufficiency from chronic congestive heart failure.
A few may have had congenital absence of all or
most of the deep venous valves. However, in
patients without clinical history, a previously
unrecognized deep venous thrombosis is a likely
pathogenic factor in the development of these skin
changes. Saphenous vein incompetence alone, in the
absence of associated deep venous insufficiency,
seldom results in stasis change in the skin.
If one takes into account certain reservations as
to accuracy and applicability, some of these data
can be extrapolated to the US population as a
whole to provide rough estimates of incidence or
prevalence of these conditions. As previously
mentioned, the data concerning pulmonary embolism are least accurate since the majority of
pulmonary emboli occur in an acutely or chronically
ill group of hospitalized patients, many of whom
will die from pulmonary embolism or from
associated conditions which predisposed them to
the development of thromboembolic disease; since
the TCHS is a longitudinal study involving
voluntary participation of individuals over a considerable period of time, most of the chronically and
seriously ill persons would have been excluded.
When figures for incidence of pulmonary embolism
derived from this study are extrapolated to 1970 US
census figures, an estimate of about 64,000 cases per
year is obtained; this value is far less than those
previously reported estimates of Hume, Sevitt and
Thomas,7 and of Coon and Willis,6 which were
obtained from hospital-based data and certainly
represents an underestimate of actual incidence,
while the earlier data6' 7 tend to provide an
overestimate.
When age- and sex-related census figures (1970
census) were used to estimate the annual incidence
of clinically recognized deep venous thrombosis and
superficial thrombophlebitis, the following values
were obtained: deep venous thrombosis: over
250,000 cases per year (200,000 in females alone):
superficial thrombophlebitis: 123,000 per year
(96,000 in females). Hume et al.7 estimated from
hospital statistics that total cases of thrombophlebitis diagnosed in US hospitals in 1966 were about
182,000.
Using the same approach for determining prevalence of stasis skin changes and active or healed
varicose ulcer, between 6 and 7 million individuals
Circulation, Volume XLVIII, October 1973
845
(about
4 million females) would be expected to
evidence of stasis skin changes in the
legs and about 400,000 to 500,000 to have had a leg
ulcer. We have been unable to find other data
concerning the prevalence of these conditions in the
US population. Gjores8 sent a questionnaire to
15,000 residents of Sweden over age 18 and then
examined a sample of 1,453 persons. His over-all
estimate of prevalence of postphlebitic sequelae
(including chronic edema, skin changes and leg
ulcers) approximated 2.2%. If one included all the
subjects with skin changes in our sample, the ageadjusted prevalence is about 5% for the US adult
population; patients with edema alone have not
been incorporated into this analysis. Boyd9 has
estimated a prevalence of leg ulcers in England of 5
per 1000; most of these individuals were probably
middle-aged or elderly person, but a breakdown by
age or sex was not given. Extrapolating from TCHS
data, prevalence of leg ulcers (active or healed)
would be about 5 per 1000 for the US population
age 20 and above.
Since each individual with any evidence of
varicose veins recorded at physical examination is
included in this analysis, many of this group did not
have varicosities of medical significance. The very
high prevalence of this finding, especially in females
and older persons, must make this one of the most
common "physical findings." We estimate that
about 40 million persons (26 million females) in the
US are affected. The estimated prevalence of more
severe varicose veins (2+ or greater) would be
about 24 million (17 million females).
have
some
Acknowledgment
The authors are grateful for the helpful suggestions
offered by Frederick H. Epstein, M.D., Leon D. Ostrander,
M.D., and Benjamin C. Johnson, M.D.
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Circulation, Volume XLVIII,
October 1973
Venous Thromboembolism and Other Venous Disease in the Tecumseh Community Health
Study
WILLIAM W. COON, PARK W. WILLIS III and JACOB B. KELLER
Circulation. 1973;48:839-846
doi: 10.1161/01.CIR.48.4.839
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