Essay on the Classification of Causes of Death

The World Health Organisation has prepared a Manual on the International Statistical Classification of Diseases, Injuries and Causes of Death. The latest revision was made in 1955.

According to this Manual, one thousand groups of diseases have been identified, and these are re-grouped in an intermediate list of 150 causes numbered Al, A2, A3, etc.

These, in turn, are regrouped into an abbreviated list of 50 causes numbered as B2, B2, B3, etc. This last list of 50 groups of causes is used for computing deaths and death rates on the basis of the causes of death.

Again, from these list 50 groups of causes, various diseases have been grouped according to their response to various health measures, resulting in five groups. These are:

I. Infectious and parasitic and diseases o the respiratory system.

II. Cancer.

III. Diseases of the circulatory system.

IV. Deaths by violence.

V. All other causes.

For those countries for which data on causes of death are available, it is possible to study the changes in the cause of death along with the changes in mortality.

In the relatively recent past, mortality resulting from Group I diseases constituted a substantial proportion of the total mortality of developed countries.

For instance, when the average expectation of life at birth in England and Wales was 50.5 years, the percentage of death due to these causes was nearly 27.

With the increase in the average expectation of life at birth to 70.5 years, the percentage of deaths from these causes has been reduced to seven.

Such striking decreases in the relative contribution of infectious and parasitic and respiratory diseases have also been observed for the United States of America, Japan, Italy, the Netherlands and Chile.

It has been observed that, with declining mortality rates, the pattern of the causes of death also undergoes changes. The United Nations, in its study of world mortality, has illustrated these changes with the help of models.

With the rise in the average expectation of life at birth from 50 to 70 years, the proportion of deaths due to infectious parasitic and respiratory diseases has declined from about 34 to nearly 11 per cent, while the percentage of deaths from cancer has increased from 5.6 to 15.2 and that of diseases of the circulatory system from 18.7 to 32.2.

Similar changes have occurred in the standard population with an “old” age structure. In Model D, however, the proportion of deaths due to infectious, parasitic and respiratory diseases is only 6.5 per cent, while the percentage of diseases of the circulatory system is 46.5 and that of cancer 16.4.

Thus the diseases of the circulatory system and cancer together account for 62.9 per cent of all the deaths in the “old” population whereas the corresponding percentage for the “young” population is

It may be noted that cancer as well as the diseases of the circulatory system, which include various types of heart diseases and hypertension, are degenerative diseases; and it is quite natural that, in populations with “old” age structures, the proportion of deaths due to these causes should be higher.

In the United States of America, the percentage of deaths due to cancer during 1936-38 was 10 while, during 1954-56, it increased to 16. Similarly, for England and Wales, this percentage rose from 13 in 1936-38 to 18 in 19E 4-56.

No striking changes have occurred in the percentage distribution of death due to violence and all other causes.

The proportion of deaths due to violence has now started showing a slight increase, while that of deaths due to all other causes has decreased in both the age structures. The decrease is, however, more in the population with the “old” age structure.

The pattern of mortality on the basis of caused of death in the developing regions is quite different from that in the developed regions, though this, too, has undergone changes over the years.

Where specific measures were taken to either eradicate or control certain diseases, the declines have been striking.

For instance, in Sri Lanka, during the very first year of the extensive DDT spraying campaign in 1946, the death rate due to malaria was 184 per 100,000 populations. Ten years later, however, it had declined to less than two per 100,000 populations.

Another example is that of small-pox, which has been completely eradicated from almost all the countries of the world.

In countries like India, Pakistan and Bangladesh, which at one time suffered extensively from the scourge of small, this dreadful disease has been completely eliminated. The proportional share of cholera in the total deaths has also gone down for many developing countries.

The figures are obviously not very reliable, as is evident from the high proportion of deaths due to “other causes”. In spite of the unreliability of the data, however, a broad picture depicting the changes in the pattern of causes of death emerges from.

It may be observed that “fever” which includes malaria, typhoid, measles, diphtheria and meningitis has all along been a very important cause of death in India. It may, however, be observed that the proportion of deaths due to “fever” is declining.

In 1980, according to Model Registration Unit of the Registrar General of India, the proportion of deaths due to fever was 9.3 in rural areas. It may also be observed that plague has been completely eradicated. The proportion of deaths due to digestive disorders was 7.3.

The percentages of deaths due to infective and parasitical diseases have gone down whereas that due to diseases of circulatory system has gone up.