1957 - United Nations Statistics Division

well as a new classification structure to bring the nomenclature
and the system of classification into line with
modern concepts.
Serious difficulties of comparability stem also from
changes in the form of death certificate being used, an
increasing tendency to enter more than one cause of
death on the certificate, and diversity in the principles by
which the primary or underlying cause is selected for
statistical use when more than one is entered. 35
Moreover, coding problems, i.e., problems in interpretation
of rules, arise constantly during the interval between
revisions. Lack of uniformity between countries
in these interpretations and in adapting rules result in
lack of comparability, which can be observed in the statistics.
They are particularly evident in causes which are
coded differently according to the age of the decedent,
such as pneumonia, diarrhoeal diseases, and others.
Changing interpretations and new rules can also introduce
disparities into the time series for one country.
Hence, large increases or decreases in deaths reported
from specified diseases should be examined carefully for
possible explanations in terms of coding practice, before
they are accepted as changes in mortality.
Differences in terminology used to identify the same
disease also result in lack of comparability in statistics.
These differences may arise in the same language in
various parts of one country, but they are particularly
troublesome between different languages. They arise even
in connexion with the medically certified deaths, but
they are infinitely more varied and obscure in cause of
death reported by lay persons. This problem of terminology
and its solution are receiving attention by the
'World Health Organization in the Centres for Classification
of Diseases-in particular in the Latin American
Centre in Caracas, Venezuela.
The lack of physicians to either attend the ill person
and certify to the cause of his death, to examine the
decedent and give an opinion as to the cause of death, or
to examine the evidence produced by witnesses as to the
possible disease which killed the person, is one of the
most important reasons for non-comparability in causeof-death
statistics. To provide a guide to the types of
certification and hence the relative value of the diagnoses,
the percentages of causes medically certified have
been set forth in Table IS, to which reference should be
made before data from Table 14 are used.
Attention must be called to an anomaly which exists
in some distributions-particularly in countries of Asia
and the Caribbean-in connexion with deaths due to
accidents and violence. In these distributions, some
deaths normally classifiable according to the External
Cause (E) classification as BE47-BE50 have been so distributed,
but a second group of deaths has been classified
only according to the Nature of Injury (N) classification.
This makes it impossible to show the 4-category "BE"
detail for these deaths and they are, therefore, shown as
a group.
Whenever known, other aberrations are noted in the
tables. However, particular care must be taken in using
distributions with relatively large numbers of deaths attributed
to "senility, unknown, and ill-defined" cause
(B45). The "all other causes" group (B46) must also be
35 Comparability of Statistics of Causes of Death ... , op. cit.
33
scrutinized. Large frequencies in these two categories,
B45 and B46, may indicate that causes of death among
whole segments of the population have been undiagnosed,
and the distribution of known causes in such cases
is likely to be quite unrepresentative of the situation as
a whole. An examination of the distributions from this
point of view, together with the general quality code
found in Table 7 and the information on medical certification
from Table 15, should provide a basis for a rough
evaluation of the quality of cause-of-death statistics. For
a more detailed discussion of the development of statistics
of causes of death and the problems involved, see Chapter
II of the 195 I Demographic Yearbook.
Table 15
For the first time in the Demographic Yearbook, a
table showing the number and percentage of deaths from
each of 50 cause groups which have been "medically
certified" is included. Table 15 presents such statistics
for the latest available year.
The classification of cause of death is the same as that
used in Tables 14, 16, and 17, namely the "Abbreviated
List of 50 Causes for Tabulation of Mortality" of the
1948 Revision of the International Statistical Classification
of Diseases, Injuries, and Causes of Death. However,
it will be noted that in this table the stub consists of the
Abbreviated List Numbers BI through BE50; for the full
titles and detailed list numbers included in each tabulation
group, reference must be made to Table 14, beginning
p. 362.
Type of medical certification is classified into the
dichotomy of "medically certified" and "not medically
certified", and only the first category is shown in Table
IS. This classification is not quite in accord with the
international recommendation,36 where it is suggested
that a "not stated" group be also distinguished. In Table
15, the "medical certification not stated" is automatically
included as a residual with "not medically certified".
Coverage: Information for 29 geographic units is shown
in Table IS, including data for cities and for ethnic
groups if broader coverage was not available.
Per cent computation: Percentages are the number of medically
certified deaths in each cause group, Bl through
BE50, per 100 total deaths from each cause. The complement
of the percentage may be interpreted as the proportion
of non-medically certified deaths, although it may
include some for which type of certification is unknown.
Limitations: All of the general limitations of death statistics
outlined beginning on p. 27 plus those specific for cause
of death set forth in connexion with Table 14 on p. 32
are important also in using data from Table IS. In addition,
there are wide variations in the meaning of the
concept "medically certified".
When a death is registered and reported for statistical
purposes, the cause of death is required to be stated in
most countries. This statement of cause may have several
sources: (I) If the death has been followed by an autopsy,
presumably the "true" cause will have been discovered.
(2) If an autopsy is not performed but the decedent was
36 Principles for a Vital Statistics System, op. cit. Principle 410 (e)
(II).