Download Comparing Cardio-Respiratory Mortality Rates: US, England & Norway and more Schemes and Mind Maps Communication in PDF only on Docsity!
CARDIORESPIRATORY DISEASE^ AS^ A^ FIELD^ FOR
INTERNATIONAL RESEARCH
D. D. Reid, M.D.
IN HIS RECENT BOOK^ on^ our^ Queen
Mary, Mr. Pope-Hennessy describes
the last illness and death in 1910 of her
father-in-law King Edward^ VII^...^ "His
convalescence from a painful accident
had been complicated by pleurisy and
in the last years of the old century his
attacks of breathlessness, attributed to
bronchitis, but also caused^ by^ excessive
smoking, had been frequent and^ bad.
He began his reign feeling ill, exhausted
and depressed"-and later-"in the last
three years of the^ reign^..^.^ his^ bronchial
colds sometimes accompanied by^ sudden
fainting fits became more frequent and
recalcitrant. To some of his family who
witnessed the terrible fits of breathless-
ness which seized^ him it^ appeared^ that
the end of his reign could not^ be far off
-yet when this came it seemed as
abrupt and shocking as death always
does."
This is a clinical^ picture^ with which
physicians in England are only too famil-
iar; and in a working man in the in-
dustrial cities of the North of the coun-
try the down-hill^ progress would^ have
been much more rapid.^ Yet^ in the
United States, "chronic bronchitis" and
"emphysema" are relatively seldom given
as causes of death. Indeed, one has the
impression that the American physician,
listening to all our talk of cough^ and
cold, of sputum and smog, secretly sus-
pects that our air pollution problems
make British physicians see all clinical
medicine through smoke-tinted specta-
cles.
International Comparisons^ in^ Mortality
Perhaps we should dismiss interna-
tional comparisons in mortality experi-
ence with the^ phrase^ once^ applied^ to
history-"a vast Mississippi of^ false-
hood"; for it is certain that many^ of
the differences between countries in their
recorded death rates from'the chronic
degenerative diseases^ stem^ from^ varia-
tions in national custom in^ the^ diagnosis,
classification, and coding of these causes
of death. I find it difficult to believe,
however, that^ the^ pattern^ of^ death^ rates
in different countries^ is^ entirely^ a^ re-
flection of the selection of standard^ medi-
cal textbooks used there. Between^ coun-
tries with standards of medical care^ as
alike as the United States, England and Wales, and^ Norway, for^ example, there
are very suggestive discrepancies in^ mor-
tality experience from^ cardiorespiratory
disease; and these differences are^ most
marked among younger people. As^ Fig-
ure 1 shows, men^ in^ the^ United States
between 45 and^54 have^ a^ death^ rate
from the arteriosclerotic and^ degenera-
tive group of heart diseases^ which^ is
almost twice as high as^ their^ contem-
poraries in^ England^ and^ Wales^ and^ three times as high as the corresponding rate for Norwegians. England and^ Wales, on the other hand, has by far^ the^ highest
rates for acute and chronic^ respiratory
affections such as bronchitis and pneu-
monia and for cancer of the^ lung. Bron- chiectasis and emphysema not^ ascribed to bronchitis are not^ included^ in^ the
JUNE, 19960 53
ARTERIOSCLEROTIC HEART DISEASES
BRONCHITIS & PNEUMONIA
RESPIRATORY CANCER
HYPERTENSIVE DISEASES
5
Is
iK7779!
68
I £I & a^6 93
;o 47
-- | 6
01 C
U.S.A. ENGLAND & NORW'Y (WHITE) WALES
Figure 1-Major^ Cardiorespiratory Death Rates^ per^ 100,000 per Annum (Males Aged 45-54 years)-from Annual Epidemiological and Vital Statistics, 1955. World Health Organization.
International Short List of Causes of
Death, but they are relatively rare causes of death in all three countries and
their inclusion would make little differ-
ence to the observed pattern. When dis-
orders where hypertension is a major clinical feature such as vascular lesions of the central nervous system and chronic nephritis are grouped together,
the United States and English rates are
remarkably alike; but both are apprecia-
bly above the Norwegian level.
Death certification and coding habits
may certainly explain some of these dis-
parities; but it seems unlikely that any
shuffling of essentially the same number
of deaths into different diagnostic boxes is the whole solution. Not only is the rate for all such causes taken together higher in the United States than in Eng-
land and Norway, but the Norwegians
have -consistently the lowest death rates
for each one of these major types of
cardiorespiratory disorder.
Figures such as these raise the ques-
tion whether the^ pattern of^ international
mortality from the diseases of middle
life is entirely random or whether it is
a coherent expression of international
variation in major factors in disease
causation. A little idle speculation could
suggest, for example, that air pollution
might be^ responsible^ for the^ excessive
respiratory disease^ death^ rates^ in^ Eng-
land and Wales; but the^ same^ explana-
tion may not apply to the differences^ in
coronary heart disease. On the other
hand, Figure 2 shows markedly different
time trends in the consumption of^ manu-
factured cigarettes between^ the^ United
States, the United Kingdom, and^ Nor-
way which suggest cigarette smoking as
a possible cause^ of^ international^ varia-
tion in death (^) rates, e.g., from (^) coronary
54 VOL. 50. NO. 6. A.J.P.H.
300,
(^2 ) z z
CZ Wu 200 a.
8 so
w
a- Ui (^) 100.
Cl: I- < w S a
FINLAND S
CANADA
NEW S ZEALAND
UNITED 0 KINGDOM
NORWAY S
FRANCE
(^0 500) 1,000 1,5o 2)000 (^) 2,500 390 3500 CIGARETTE CONSUMPTION PER ADULT PER ANNUM
Figure 3-Relationship of Levels of Smoking of Manufactured Cigarettes^ and^ Death Rates at Ages 45-54 from Arteriosclerotic Heart Disease.
habits and conditions of life which pre- dispose to disease and premature death. If they do not, we should at least try to define the limits of our ignorance and stop drawing unwarrantable conclu- sions from them. This means in prac-
tice, I believe, special surveys first, to
assess the variability between particular
countries in the diagnosis and classifica-
tion or coding of causes of death and,
second, to verify that differences in death rates truly reflect differences in the prevalence or incidence of^ specific dis-
eases in the areas to which^ they apply.
Differences between national vital sta- tistics offices in^ their practice in^ the classification and assignment of the re- ported cause of death may be important and some studies of this (^) aspect of the
problem are now in hand. Samples of
death certificates from various (^) countries are being coded in other national offices
and some discrepancy certainly exists,
e.g., in the coding of the cardiovascular
disorders (Morrison, personal communi-
cation).1 The same principle of using
standard test material has already been
applied in some^ of^ our own^ work^ on^ the
regional distribution of cardiorespiratory
mortality within the United Kingdom
(de Fonseka^ 1958). A^ series^ of^ clini-
cal histories of (^) patients dying from the more complex forms^ of cardiac^ failure were (^) presented to 87 members of the
British College of General Practitioners
who differed^ in^ their training, experi-
ence, and^ place of practice. These^ doc-
tors were then asked to complete a
VOL. 50. NO. 6. A.J.P.H.
I..
56
RESEARCH IN CARDIORESPIRATORY DISEASE
"death certificate" for each of these pa-
tients. The certificates were then coded
in the usual way at our Registrar-
General's Office. Figure 4 shows the
distribution of assignments thus obtained
in the case-typical of those in whom
difficulty arises-of a woman of 61 who
gave a history of chronic cough and
increasing breathlessness who died after
admission to hospital with signs of pul-
monary congestion and right-sided heart
failure. While it is tru that 65 per cent
of these British doctors agreed in their
allocation of cause of death, the difficulty
of distinguishing between cardiac and
respiratory modes of dying in such cases
is patent. Clearly, some international
studies along the same lines are (^) needed
to assess the numerical importance of
such differences in diagnostic habit in
the certification of cause of death.
The Standardization of Diagnosis
At the same time we need to determine
by appropriate field surveys the rela-
tionship between death rates from a
ARTERIOSCLEROTIC HEART DISEASES OTHER HEART DISEASES
PNEUMONIA
BRONCHITIS
OTHER RESPIRATORY DISEASES
specific disease and its prevalence in
the population to which that death rate
refers. In such comparative studies pre- cision in disease definition is funda- mental. As A. N. Whitehead put it (^) "a
definition a day keeps the charlatan
away." Recent British^ experience in
surveys of chronic respiratory disability
in different areas suggests that two tech-
nical methods may be helpful in this
context-the detailed standard clinical
questionnaire and a simple test of lung
function suitable for use in field condi- tions.
By careful wording of the questions
and briefing the survey team, it proved
possible to obtain quite consistent an-
swers to questions such^ as:^ Is^ your
breathing different in summer and win-
ter?
Once individual symptoms have been
elicited in this way, an epidemiological
study of defined symptoms becomes pos-
sible. We have^ found, for^ example, that
foggy weather has^ a much greater effect
on city dwellers than on country people
and itemized information like this is
@/ OF 87 PHYSICIANS 10 20 30 40 Sp 60
OTHER DISEASES
Figure 4-Distribution of "Certified Cause of Death" in a Standard Case by 87 British General Practitioners.
JUNE, 1960 57
RESEARCH IN CARDIORESPIRATORY DISEASE
There is much to be said, therefore, (^) for the survey of a specific occupational group common to all countries, such as postmen or transport (^) workers. Not only are they usually both (^) accessible and
cooperative, but the^ similarity in job
and (^) social status standardizes at least two of the variables in the equation. The geographical distribution of their morbidity experience can match quite closely the regional death rates for the population as (^) a whole. The wastage rate from death or permanent disable- ment because of chronic bronchitis
among British postmen, for example,
correlates quite highly (r=0.68) with the death rate from that cause for all their (^) contemporaries in the area where they work.
Opportunities in International
Com parisons
One of the most (^) intriguing opportuni-
ties offered by similar studies carried
out, e.g., in countries as atmospherically
different as the United Kingdom and
Norway, is the possibility of making
detailed between-study (^) comparisons. In both countries, a (^) relationship may be
observed between cigarette smoking and
emphysema. But in the United King-
dom, the effect of smoking may accentu-
ate the results of air pollution to give
a steeper trend. In any event, the defi- nition and standardization imperative in such studies may at least answer the rather plaintive (^) question recently put (Mitchell, 1959) in an American sym- posium on the subject-"Is 'bronchitis' as the British use the term partially or wholly synonymous with 'emphysema' as we use the term?" We might even be able to resolve our present differences about which of these conditions is cart and which is horse and to establish whether cor pulmonale as we see it forms any appreciable part of American death rates from heart disease. In the United States, recorded deaths from such cardiorespiratory conditions as emphysema. while still relatively in- frequent, are mounting faster than any other cause of death (^) (Dorn, personal
communication) .'^ The support being
given by the National Heart Institute for
an international meeting to discuss what,
if anything, can be achieved by joint
United States-United Kingdom studies in
this field is therefore (^) timely; for, as the story of^ King Edward proclaims, death from these obscure disorders spares neither king nor country.
REFERENCES
- Morrison, S. Personal communication.
- (^) de Fonseka, T. E. (^) J. Studies in the (^) Epidemiology of Cardiovascular Disease. Ph.D.^ thesis, University of Lonidon, 1958.
- Dorn, H. Personal communication.
Dr. Reid is with the Department of Medical Statistics and Epidemiology, Lon- don School of Hygiene and Tropical Medicine, London, England. This paper was^ presented before^ a Joint^ Session^ of the^ Epidemiology^ and Mental Health Sections of the American Public Health Association at the Eighty-Seventh Annual Meeting in Atlantic City, N. J., October 20, 1959.
JUNE, 1960 59
