demographic yearbook annuaire demographique 1951

from the previous lists. 6 The new classification serves a dual
purpose-to classify causes of illness as well as causes of
death for statistical use. As an extension of the mortality
list to serve also as a morbidity list, it necessarily differs
considerably from the previous lists. However, the general
structure of the old classification has been preserved because
of the demonstrated usefulness of the basic framework.
The Sixth Revision detailed list consists of 16 sections
subdivided into 612 categories of diseases and morbid conditions,
plus an additional section concerned with injuries
and consisting of a dual classification which provides 153
categories for the classification of external causes and 189
categories for the characterization of injuries according to
the nature of the injury. Provisions are made for securing
still more detailed information by further subdivisions of
many of the categories. However, the use of these subdivisions
by nations is optional.
The detailed list is prescribed for classification purposes,
but the following special lists are also provided for tabulation
and publication purposes: (1) an intermediate list of
150 causes for tabulation of morbidity and mortality by age
groups and other demographic characteristics; (2) an abbreviated
list of 50 causes for tabulation of mortality in administrative
subdivisions; (3) a special list of 50 causes for
tabulation of morbidity for social insurance purposes.
PROBLEMS OF JOINT-CAUSE CLASSIFICATION
The production of statistics on causes of death is relatively
simple when only one clearly defined morbid condition is
involved. However, when complications of a disease arise,
or when there is an intercurrent infection, more than one
condition may contribute to death. In such cases, either the
medical certifier or the statistical office is faced with the
necessity of selecting a single cause for statistical tabulation.
Variations in selection procedures
It was with this problem in mind that Jacques Bertillon
appended to the 1900 revision of the International List of
Causes of Death a commentary noting the most frequent
complications of each important disease and indicating
those complications which need not be taken into account.
He also developed the following general rules to be followed
when two or more causes of death were reported jointly:
"Rule 1. Ifone of the two diseases is an immediate and
frequent complication of the other, the death
should be classified under the head of the
primary disease.
"Rule 2. If it is not absolutely certain that one of the
diseases is an immediate result of the other,
we must see if there is a very great difference
in the gravity of the two, and classify the
death under the head of the more dangerous.
"Rule 3. When among the two causes of death there
is a transmissible disease, it is preferable to
assign the death to it, for statistics of infectious
diseases are particularly interesting to
the sanitarian, and it is important that they
shall be as complete as possible.
"Rule 4. If a disease whose evolution is rapid is given
in connection with another whose evolution
6 World Health Organization, Manual oj the International Statistical
Classification oj Diseases, Injuries and Causes oj Death, Vol. I and II,
Geneva, 1948.
is slow, it is preferable to charge the death to
the first. Again, if a death is simultaneously
attributed to a disease and to an external
violence, it is usually proper to assign it to
the latter.
"Rule 5. Finally, if none of the preceding rules is
applicable, the diagnosis most characteristic
of the case should be selected." 7
These rules have long served as guides for many national
statistical offices, though, as a result of their rather general
character, the specific manner in which they have been
applied has varied considerably. Thus, a report by Michel
Huber, prepared in 1926, showed that while the specific
rules differed greatly, most countries accorded precedence
to the causes of violent death, to infectious diseases, and to
diseases most frequently causing death, in the order named. 8
But the major weakness in such general rules is the absence
of a definitive procedure for selecting the principal or primary
cause of death.
The findings of a questionnaire survey made in 1947 by
the United States Committee on Joint Causes of Death 9
were similar to those reported by Huber twenty years earlier.
Some progress had been made in the adoption of
medical certification forms designed to record the physician's
opinion on the sequence of events leading up to death
so that the various contributing causes could be evaluated.
However, there seemed to have been few developments of
definite rules of procedure for selecting the main cause of
death. Many of the countries apparently had no rules at all
or only a few very general rules; on the other hand, some
countries had adopted a comprehensive set of rigid rules
(e.g., the Manual of Joint Causes of Death, adopted by the
United States; also, the procedures developed in England
and Wales, which provided the basic pattern for the international
rules adopted in 1948).
The application of different procedures would obviously
produce different results. The extent of these differences was
demonstrated in a study made in 1935. 10 The United States
Bureau of the Census, at the request of the Commission for
Revision of the International List of Causes of Death, prepared
descriptions of 1,032 cases, each involving from two
to five causes of death. These cases were submitted to the
statistical offices of various countries with the request that
they be classified according to the selection principles followed
currently in those offices. The analysis of the returns
included data for 18 countries.
The return of each country was compared, cause by
cause, with that of each of the others and percentages of
agreement were computed on the basis of each comparison
for each cause and for all causes combined. (One group,
involving deaths of infants under one year of age, was
treated as a separate category). As shown in the table below,
the overall average agreement in the selection ofthe primary
cause of death in the 1,032 cases was only 57.5 per cent.
7 United States Census Office, Manual oj International Classification
oj Causes oj Death, Government Printing Office, Washington, 1902,
page 13.
8 Huber, Michel, "Report on Methods of Issuing Certificates of
Death and Its Causes," Bulletin de l'Institut International de Statistique,
Vol. 22, Livr. 3, The Hague, 1926, pages 23-66.
9 World Health Organization, Problem oj Joint Causes oj Death, Final
report oj the United States Committee on Joint Causes oj Death. WHO.IC/
MS/11, Rev. 2.
10 United States Bureau of the Census, Classification ofJoint Causes
of Death. Vital Statistics-Special Reports, Vol. 5, No. 47, August 30,
1938, Washington, 1938.
20