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22
Phthisis death-rate per 100,000 living. Phthisis, per cent. of all causes.
Age period.
1881-90. 1891-00. 1901-10. 1881-90. 1891-00. 1901-10.
Females—
5-15 42 32 26 9 8 9
15-25 142 107 87 36 32 32
25-45 286 221 156 33 29 26
45-65 228 201 164 10 9 9
Total of Rates 698 561 433 88 78 76
1901-10=100 161 129 100 116 102 100
Relation of
mortality to
urbanisation.
Differences in the incidence of phthisis mortality, similar to those found in
populations of differing social circumstance, and in successive decennia, are also
found in populations living in different classes of area, and here again the variations
are correlated to the deaths from all other causes.
The facts are broadly illustrated in the diagram on the next page. The upper
parts of each section of this diagram show phthisis death-rates (1) according to social
condition; (2) in successive decennia; and (3) according to class of area of residence.
In the lower part of the diagram the phthisis death-rates are shown as a percentage
of deaths from all causes for each age. It will be seen that in all three sections
the divergence between various groups of population shown in the upper part of the
diagram are almost eliminated in the contours shown below them.
The diagram relates to males only, but the female rates give similar results.
It will be noticed that both when figures relating to successive decennia are
considered, and those relating to different groups of population, there is not an exact
parallelism between the variation of the phthisis death-rate and the death-rate
from all causes. One finds that the phthisis deaths in the poorest of the social groups
and in earlier decennia and also in the more urbanised districts are all relatively
higher than the corresponding deaths from all causes in these groups of population.
This points to the fact that, although in general the phthisis mortality responds
to the same conditions as those which determine the general death-rate, there is
some condition which is specific to the phthisis mortality.
Nutrition
the chief
factor.
From the clinical point of view, Osler tersely sums up the position with regard to
phthisis thus ("Principles and Practice of Medicine," page 332): "The cure of tuberculosis
is a question of nutrition; digestion and assimilation control the situation;
make a patient grow fat and the local disease may be left to take care of itself."
It will, therefore, be expected that any conditions which affect the nutrition of
the general population will have a somewhat greater effect relatively upon the
phthisis death-rate than on the death-rate from other causes. This fact is well
illustrated in the exceptional conditions which obtain in war, famine or other
adversity, when the phthisis death-rate will be found to be still more increased
proportionately, while, on the other hand, in times of prosperity and improved food
supply a relatively greater decrease is found to occur. It is of interest to recall in
this connection the experience of this country and all the European countries which
were involved in the Great War (1914—18).
Types of
phthisis.
A remarkable difference is found in the age-incidence of phthisis in London
compared with that of Ireland on the one hand and of coal miners on the other,
(see diagram on page 24, where the phthisis death rates per thousand living at
certain age periods are shown for each of the three populations). These three populations
were taken by the late Dr. Brownlee as typifying three different kinds of
phthisis. Ireland representing what he called the "young adult type," London
the "middle-age type" and the coal-miners the "old age type." But as has been
observed above, a consideration of the phthisis death-rate which does not take