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A study of tuberculosis mortality in England and Wales
March 1949
50
A Study of Tuberculosis Mortality in England and Wales* By PERCY STOCKS
Chief Medical Statistician, General Register Office Introduction. - If we have not reached the
point at which tuberculosis is the world's number one health problem, it would seem that we are rapidly approaching it, not so much because of an increase in the prevalence of the disease as because of the dethronement of other scourges by the discovery of means by which their ravages can be reduced very greatly. With the birth of the World Health Organization there now seems a reasonable prospect of pulling down malaria, venereal and some other diseases from their pedestals as killing agents. But we cannot yet say that of tuberculosis, over which the road to victory in the world-wide sense is going to be a tough and difficult one. The beginning of industrialization in many countries has been bringing with it an insidious spread of tuberculosis, and since we know as yet of no better prospect for them than what Dr Gilmour has called the 'long and painful process' of gaining some racial immunity, the countries of the East and some of our colonies are not in a h a p p y position. In India an estimate of some 289 million suffering from the disease with only a handful of tuberculosis officers to look after them brings the problem into startling perspective. Even in such an enlightened country as the United States of America we still see tuberculosis death-rates three times as high in the coloured population as in the white, and in New Zealand, Malaya and parts of Africa the racial contrast is considerably greater. Mortality Trends Over75 Years.- Looking at the more cheerful side of the picture, we see that in the United States the crude death-rate from tuberculosis amongst w h i t e males has fallen in thirty-five years since 1911 b y three-quarters and amongst white females by more than five-sixths, the present rates being about 4o. and 2o per lOO,OOO respec*An address given
to
tlvely. In England and Wales in the same period the crude rate for females has falletl to one-third of its 19I i value, and fig. I compares the downward trend of the rates for females in the two countries. Before the first world war U.S.A. had higher rates than ours; and during that war mortality increased in both countries, reaching peaks in the influenza year 1918. Then came a steep fall bringing the rates close together in 192o; but whereas the fall continued rapidly until 1921 in U.S.A., it was arrested TUBERCULOSIS (ALL FORMS) Female Death-Rates 1910-46 I~O -
CRUOE
--
US A (WHITE) CRUDE . . . .
r~"
\
,
15-
*~,+ ,+
SD-
" ..+
'1" ;"
~1"'~'l |~+IP +.
25-
01+910
" ~l-i
1~2.
.
.
.
Q ~IG,
;;+4.
.
.
.
.
I.
in 192o in England and Wales, with the result that U.S.A. showed a large advantage in I921 which has been maintained ever since. The disparity gradually increased fi'om about 17 per lO%OOO in I921 to about 25 in the early thirties and has averaged 22 in the last few years. The ratio between the two rates has changed much more markedly, from 82 per cent in 1921-23 to about 50 per cent in I944-46. T h e diagram shows also how great was the disturbance to the trend of female mortality from tuberculosis in the first world war compared with that in the second war. The effect of the second war on English women
the British Tuberculosis Association on November i9, i948.
March 1949
TUBERCLE
was little greater than what occurred in the first war amongst American women. From I933 onwards the dotted curve shows also the trend of standardized mortality, which has not fallen quite so much as the crude rate. The apparent improvement over the last I5 years is somewhat exaggerated by the crude death-rate for females, owing to the increasing proportion of older women in the population whose tuberculosis mortality is lower.
5f TUBERCULOSIS, RESPIRATORY--1875- [ 947 C.N.I. On Logarithmic Scale (Wars Omitted)
TUBERCULOSIS--ENGLAND AND WALES Comparative Mortality Indices (Persons) 1871-1947 ~
~
L,
ALL FIll1klS . . . . . ~ESPIRATO/~Y IBS.0
18'90
, I~O0
, ~10
--., t92o
, ~30
.., 1940
.. 19S0
Fzo. 3.
--
,
-,
r
F~o, ~.
Fig. 2 shows how the comparative mortality index for tuberculosis of both sexes together changed between I87I and i93o , this being indicated by the broken line. The continuous line, which shows the trend of the C.M.I. for respiratory tuberculosis of perscns, is drawn between quinquennial points up to I9z 3 and then by single years to I947. Each C.M.I. is based upon the year i938 as unit, so the coming together of the two curves does not mean that there was zero mortality from non-respiratory tuberculosis. The fact that the two curves passed through a common point both in i873 and 1929 shows that between those dates the relative improvement was the same for respiratory as for non-respiratory tuberculosis. During the first half of that period the respiratory index was improving more quicldy, and during the second half nonrespiratory gradually made up the lost ground. When tile points on the respiratory tuberculosis curve are plotted on a logarith-
mic scale, as in fig. 3, it is seen that the trend between 1875 and 191o foliowed almost an exact straight line, meaning that the percentage reduction in moztality in a unit of time was constar~t during the thirtyfive years, after smoothing out fluctuations due to cold winters, influenza and other temporary disturbances. After recovering from the first world war, the downward trend became slightIy steeper, with the result that in the period I931-39 the points were tklling more and more below where they would have been if the rate of improvement during I875-z9Io had continued without interruption. After the second setback in the early years of the second war, the rates ofi945, i946 and 1947 were again below the values expected if the steady fall of the thirty-five years before I9io had continued without change iia the thirty-five years. Despite setbacks, some progress in reducing mortality from respiratory tuberculosis has been m a d e during the last ten years. The crude death-rate in z936-37 was 565 per million. Ini938-39 it was down to 518, but continuing to calculate the rate on the total population ir~cluding all non-civilians, since rejection at recruitment and invaliding out of the tuberculous made the crude civiIian death-rates meaningless, the rate in I94o-4 I was back again at the same level as in
March 1949
TUBERCLE
52
i936-37. Then followed another sudden drop to about 503 in I94~-43, and a further fall in I944 to 474- The next two years brought small improvements, b u t in z947 the rate was 468, not much different from that of 1944 9 The comparative mortality index, being a civilian rate and greatly affected by selection owing to the high death-rate at the service ages, is not informative during z94o-46 , that is until demobilization was nearly completed, but we can usethlly compare the I947 index with the pre-war figures. The unit for this standardized index is the mortality of I938 , and both in I936 and z937 the index was just about x.I, whilst in I947 it was '93, an improvement of '5 per cent in the ten years. The crude death-rate based on total population showed , 7 per cent fall, so no great difference is m a d e by standardization for age. O f course if we compare I947 with the more favourable years ,938-39, the decrease does not look so good, being 7 per cent for the C.M.I. and ~o per cent for the crude rate in eight and a half years. Perhaps the fairest measure of the improvement during the last ten years is obtained b y comparing the C.M.I. for I947 with that for the five years centred at I937, which gives 13 per cent fall for respiratory tuberculosis. This ignores the t e m p o r a r y rise during the early part of the war. I f we start from , 8 5 , 55 and follow the comparative mortality index for the respiratory form to I931-35 at ten-year intervals the successive percentage falls were 9, **, x7, 2x, I9, x6, 2I, 24. It appears that the rate of improvement during the last ten years has been considerably less than that which occurred in Ages
any ten-year period between ,87z-75 and r93z-35. Death-rates by Sex and Age. - Turning now to the recent changes in mortality at various ages for each sex, I have set out in a series of tables the average rates of the last four periods of two years expressed as percentages of the average rate in I938-39 , using always totaI rates, including non-civilians both ia the deaths and populations. The base period I938-39 was a very favourable one, as [ have pointed out, but for the purpose of comparing the recent changes in different sex-age groups it is best to use the last two years before the influences of the war began to operate. For respiratory tuberculosis, the overall trend from I938-39 to I946-47 showed a fall of I ~ per cent in the crude rate at all ages and of 789 per cent in the comparative mortality index. In the tables the period I931-35 has also been inserted tO show what happened between then and I938-39. T a b l e I shows the trends for respiratory tuberculosis amongst boys and girls. All these rates were falling very rapidly between ' 9 3 I and z939, and then increased at the beginning of the war. For some reason for which I can offer no explanation tl~e deathrates amongst children under 5 have remained substantially above the level they reached in i938-39, and show no tendency to recover from the change which took place at the onset of war. The z946-47 level is about 4 ~ per cent above that of I938-39 , whereas if the pre-war trend had continued it would have been about 5 o per cent below. For boys aged 5 to io the
TABLE I 1940-4 z
1931-35
1938-39
194~-43
1944-45
1946-47
144 263 z6o
ioo zoo ioo
12o i7~ Io9
I~8
I~2
75
112 134 84
123 Iz6 65
~8o ~79 174
~oo zoo ioo
17o if2 ~23
17o 79 88
17o Io6 80
159 zo2 8z
Boyx O - -
9
,
--
,
.
io-x 5 Girls O - -
9
~ Io-15 --
~
B
W
m
a
e
9
, .
t
March 1949
TUBERCLE TABLE II 1940--41
Ages
1931-35
I938--39
I37 I38 I3I 133
,oo Ioo Ioo
II2 98 IO7
100
53
I94~-43
I944-45
I946-47
IIO
98 83 92 97
77 79 87 85
66 70 85 80
12o 112 I~ IO8
99 97 95 89
86 9t 9~ 87
80 92 97 85
Men i 5-
..
20-
..
25-
..
34-45
9
~
Women I N-
..
139
Ioo
20~
..
121
IO0
25-
..
1~ 7
Ioo
35-45
138
IOO
1938-39 rate was very low and it increased again greatly in 194o-41 , a n d although falling again it has not regained the best level attained before the war. For girls aged 5 to IO no substantial increase occurred, but the pre-war downward trend has been arrested. Amongst children aged i o to 15, however, present mortality is well below that of I938-39. Whether this unsatisfactory trend of death-rates from respiratory tuberculosis at ages under IO has anything to do with changes in diagnosis at these ages I do not know. At their face value the rates contrast strangely with recent trends o f child mortality from other diseases, a n d also with those for respiratory tuberculosis in females of every age over I o. Table II shows the trend of mortality since 1931-35 amongst young adults between 15 and 45. Their rates were declining in the decade before the war quite rapidly for each sex and age group, though not so quicldy for women between 2o and 35 as the others. The I931-35
Ages
I938-39
fall was broken in 194o-41 , but had already been resumed by 1942-43, and has continued since then for most of the groups, though more slowly than in the pre-war years. Amongst men under 25, however, the decline in death-rate between I938 and 1947 has been almost as great as if the war had not intervened. Women aged 25-35, on the other hand, show little improvement since 1938-39. Table I I I shows the trend of rates for m e n and women of various ages over 45. Here there is a great contrast between men and women. Mortality of women between 45 and 65 was only slightly raised in I94O-4I, and the downward trend was quickly resumed, improvement since i938-39 being about one-fifth9 At 65 to 75 the fall has amounted to 8 per cent, and at higher ages the war did not interrupt the decline9 Amongst men of 45 to 55 the rate has fallen IO per cent since I938-39 , but at 55 to 75 rates are now higher than they were even in 1931-35 and show no sign of improving. At ages over 75 the death-rate
TABLE I I I I94o-4I
I942-43
I944-45
I946-47
Men
45-- 9149 55-- 9 65-- . .
'' "' 9149
75 a n d o v e r
119 IO~ IO9
IO0 IO0 IO0
IO5 I13 IIO
99 IO 7 IO9
92 104 I16
9~ IO5 120
122
IOO
IR2
I32
i31
135
I37 I29 i3o ii6
ioo ioo Ioo IOO
iOl Io4 io 7 92
Women
45- 9149 ., 55- .9 ., 65- .9 .. 75 and over
88 9~ 92 87
8I 79 91 79
76 8I 92 86
54
March 1949
TUBERCLE
has increased b y one-third since i938-39 , and is also above that of i931-35. T h e contrast between recent trends of mortality from respiratory tuberculosis in men over 55 and other sections of the adult population is very pronounced, and it will be noted that the decline between 1931 a n d 1939 was small for men aged 55 to 75 compared with all other groups. T h e reason for this contrast is not clear. It is easy to say it is due to more complete certification of what was previously called bronchitis, and that it is due to more frequer~t use o f x-rays, but w o m e n of ages over 55 would also be affected b y these factors, and their rates have fallen. A more likely explanatioll is that the men who are now aged 55 to 80 bore the brunt of the first world war, and at the same time lost a considerable fraction of their fittest members; and in the second world war m a n y of the same men were again subjected to heavy strains of another kind. Fig. 4 shows how great a change has occurred in the age distributior~ of male death-rates as a result of the continued downward trend amongst young men and upward trend amongst older men. In ~85I-6O the age period of maximal male death-rate was 2o to 25; in 186I-9o it was 35 to 45; from 1891 until I938 it was 45 to 55, but from 1938 onwards the peak has been at ages 55 to 65. In the United States of America the present peak of mortality is at 65 to 75 for white males and at 45 to 55 for non-white males. It must be remembered that a graph of death-rates experienced at successive ages by a " c o h o r t " ofmales born at a given time would differ greatly from fig. 4, owing to the progressively improving conditions they encountered as age advanced. For females the story has been different. In I 8 5 I - 9 o the age period of maximal death-rate was 25 to 3 5 ; ir~ I891-I9IO it had progressed to 35 to 45, b u t in I 9 1 I - 2 o it moved back to ~o to 35, and since then it has been at ages 2o to 25. In the United States there are now two maxima for white
RESPIRATORY TUBERCULOSIS--ENGLAND AND WALES Death-Rates by Sex and Age in 1931-35 and 1947 !5C
. A
;/ "\',
0,.' *....
:OO
/ ':~,
\X
f! : :l, ' ' , ~
', '\ d /
:'\
50
9
i.r ', g
0 tO
20
30
10
50
60
70
LtO
Fro. 4.
females, one at 25 to 35 and the other at 75 and over, the first being a slight hill rather than a peak; but for non-white females there is still a sharp peak at 20 to ~5 similar to that for English women. T h e vcry different bchaviour of male and female death-rates in the last ten years cannot be explained in a facile way by x-rays or fashions in death certification; they are a continuation of a process which has been going on for a long time, but which seems to have b e e n intensified in recent years. T h e death-rates of children from nonrespiratory tuberculosis were declining by about 4o per cent every ten years in the period between the wars. The average rates of 1946 and I947 are compared with the average rates of 1936-37 in Table IV. Boys and gifts show 35 and 39 per certt improvement respectively at ages under 5, 32 and 15 per cent at 5 to lO, and 16 and 13 per cent at IO to 15. The war has retarded the rate of falI at the school ages, though not for younger children.
Regional D eath-rates.--Let us now look at another aspect, namely the rcgionaI differences between death-rates from respiratory
March 1949
TUBERCLE
55
TABLE I V
Boys oA v e r a g e a n n u a l rates p e r million living: z936-37 . . . . . . 476 1938-39 . . . . . . 431 I946-47 . . . . . 308 P e r c e n t a g e decrease in I946-47 c o m p a r e d with: i936-37 rate . . . . --35 I938-39 rate . . . . --29
Girls
5-
to-z5
o-
5-
zo-15
r64 I42 i12
1o6 9r 89
418 383 256
135 128 iI 5
1oo 97 87
--3 ~ --2I
--16 -- ~
--39 --33
--15 --io
--13 --Io
TABLE V.--REsPIRATORY TUBERCULOSIS AT AGES I5--45 R e g i o n a l d e a t h - r a t e s in i 9 3 ~ - 3 6 p e r cent of n a t i o n a l rate 9 P r o p o r t i o n a t e mortalities~ b a s e d on all non-violent causes, per c e n t o f n a t i o n a l p r o p o r t i o n , I 9 3 2 - 3 6 a n d i942-46. E s t i m a t e d p e r c e n t a g e changes in d e a t h - r a t e from those of I 9 3 2 - 3 6 to those of I94.0-46 (civilians).
Relative proportionate mortality Relative death-rate
Regions (in order of i932-36 death-rate)
i93~-36
1942-46 z93~-36
(civilians)
Percentage change in death-rate
Males .aged 15-45 North I . . . . Wales I .. Wales II .. North IV .. North II Greater London Midland I R e m a i n d e r of'S'outh East Midland II . . . . South West . . . . North III . . . . East . . . . . . C o u n t y boroughs .. O t h e r u r b a n districts R u r a l districts ..
9
9
i3i i~i zo8 Io7 io 3 Io 3 1oo 91 89 86 86 84
Io 9 io 3 ioi 93 lOO III 99 io 7 98 99 86 Io5
zo6 ioi io 4 93 99 III 1~ Io2 9~ 98 84 90
+ i + 3 + 7 + 4 -1- 3 + 4 +z2 o ~ -F 3 -F --I,
i~ 4 9~ 73
io8 94 88
io6 94 85
+ + +
I56 I37 I33 Iz5 Io5 ioi 99 96 92 87 84 83
II 3 Io6 Io8 IO4 Io4 92 lOO io2 io8 97 8~ 98
II 7 II6 99 Io7 Io3 95 95 9I Io7 94 86 93
--2~ --I 7 --3z --23
ii6 96 87
~o6 94 89
rio 94 83
--22 --25 --3o
2 4 2
Females aged z5-45 Wales I .. North I .. Wales II .. North II .. Midland I .. North IV .. Midland II .. East Greater London S o u t h West .. North III R e m a i n d e r of'S'outh East C o u n t y boroughs .. O t h e r u r b a n districts R u r a l districts ..
.. 9.
--2 5
--23 --29 --32 --25 - 27 --~: - ~8
56
TUBERCLE
tuberculosis at two age-periods 15 to 45 and 45 to 65 for each sex. The estimation of death rates at particular age-groups in parts of England and Wales h a s been rendered difficult by two factors, the absence of a census in I94X and the great movements of population caused by the war. Although the GeneraI l~egister Office has kept track of the movements of people of all ages combined by means of the National Register, and also since I944 of children under 5 and 5 to 15 b y means of their special ration books, we have not found it practicable to keep statistics of the sex-age distribution of the adult movements. T o help us in repairing this gap, we had a count made by sex and age of the maintenance registers of the National Register in every area of the country at the end of I947. It is expected that the results, when they have been tested in every possible way, will be m a d e generally available. Meanwhile, the only way we can estimate deathrates in regions at ages z5 to 45 and 45 to 65 by sex during z942-46 is by an indirect method based on proportionate mortality, involving certain assumptions as to what happened to the total death-rates from all non-violent causes. What I have tried to do is first to give a picture of the regional death-rates from respiratory tuberculosis for the four sex-age groups during the five-year period 1932-36, based on tolerably good population estimates for that period; and then estimate the percentage changes in death-rates which occurred in the ten-year interval from I93~-36 to I942-46. This was done by crossing a bridge from absolute death-rates to proportionate mortalities based on deaths from all non-violent causes in i932-36 , and then recrossing a parallel bridge fi~om the known proportionate mortalities of civilians in I942-46 to the unknown absolute deathrates of civilians. The assumptions ilavolved were (I) that recruitment for the Services affected mortality in the regions equally and (~) that when the death-rate at a given age from all non-violent causes changed in
March 1949
England and Wales as a whole, it changed in the same proportion within each region. The constancy of regional rates from all causes in terms of the national rate of the same period before the war made the second assumption a reasonable one, and although the resulting percentage changes in tuberculosis death-rates in the ten years, shown in Tables V and VI, can only be regarded as approximations, they are very unlikely to be wide of the mark for any region. (For Table V I see opposite page.) T h e first map shows the death-rates of males aged 15 to 45 from respiratory tuberculosis in the regions during r932-36 expressed as percentages of the national rate. Absence of any shading means less than 8o; open horizontal lines mean 8o to 89, close horizontal lines 9o to 99, cross-hatching Ioo to Io 9 and black means I Io or over. North I and Wales I were black, with 3 z and eI per cent excess; North II and IV, Wales II and Greater London showed small excess; Midland I was just average, and the
Map No. T.
March 1949
57
TUBERCLs
TABLE VI.---I{EsPIRATORu TUBERCULOSIS Regional death-rates in i982-36 per cent of national rate. on all non-violent causes, per cent of national proportion, percentage changes in death-rate from those of r932-36
Relative proportionate mortality
Relative death-rate
Regions (in order of i932-36 death-rate)
I98~-36
AT ACES 4 5 - 6 5 Proportionate mortalities, based I93~-36 and I942-46. Estimated to those of I942-46 (civilians).
I94~-46 I932-36
(civilians)
Percentage change in death-rate
Malaaged 45-65 Greater London .. North IV Midland I Wales I I North I I I North II North I Wales I Remainder of South East Midland I I . . . . South West . . . . East . . . . . . County boroughs .. Other urban districts Rural districts ..
II8 II7 m8
II8 99 Io9
93 9o 90 84 83 74 66
98 94 88 8I 98 92 84 8o
II6 97 iII 97 9~ 99 96 91 96 96 84 84
to2
mo
I3I 8i 59
II3 84 75
II3 87 76
- 9 -- 5 -- 7
I39 I25 m4 m2 IO7 I~ 97 97 95 89 84 84
I25 Io7 IO3 I~ 3 IO7 99 85 IO8 Io3 97 97 75
lO5 99 II7 I24 96 98 84 ~I 9 94 94 98 69
--45 --39 --25 --34 --4I --35 --35 --28 --4 ~ --36 --33 --40
122 88 85
1m 87 89
ZiG 88 85
--85 --34 --37
io2
0
9
a
0
.. ..
--IO --to -- 7 --~ --11
3 --I- 3
--
--If
-- 4 -- 8 -- 5
Females aged 45-65 Wales I I .. North I Wales I Midland I Midland II North I I North IV Greater London South West .. East Remainder of South East North I I I .... County boroughs . . . . . . . Other urban districts .... Rural districts . . . . . .
9. .. 9. .. 9. 9. 9. .. 9. 9. 9. ..
rest of the Midlands, East and South had rates 9 to 16 per cent below average. The most curious feature was North I I I , the West Riding, with a rate 14 per cent below average. W h e n expressed as proportionate mortalities irt terms of that of E n g l a n d and Wales the order was changed considerably, Greater L o n d o n r a n k i n g highest and North I V (Lancashire and Cheshire) rankir~g quite low. The reason for t h a t was that a l t h o u g h these regions had very similar
tuberculosis death-rates, N o r t h I V h a d a m u c h higher death-rate from all other causes than had Greater Lortdon. H o w e v e r , the West R i d i n g ranked lowest a m o n g s t the regions for proportionate mortality in 1 9 3 2 . 36, and this was again true irt I 9 4 2 - 4 6 . The only regions showing a n y substantial change in p r o p o r t i o n a t e mortality in 194~-46 were M i d l a n d I where it increased, a n d the East where it decreased. T h e change in the national d e a t h - r a t e in
TUBERCLE
58
the ten years to z 942-46 for men of this age group was a rise of 4 per cent, the increase being accounted for b y the high degree of civilian selection of men of these ages in the war period for tuberculosis. The only regions showing appreciable variation from the average change were Midland I with a rise of I~ per cent, East with a fall of II per cent and M i d l a n d II with a fall of 2 per cent. North I I I maintained its low position. The second m a p shows the position in i932-36 for females aged 15 to 45. Again the highest rates were in Wales I and North I, with 56 and 37 per cent excess, Wales II following closely with 33 per cent excess, and then North II with 15 and Midland I with 5 per cent. The Southern regions and North I I I had low rates, that of the West Riding being I6 per cent below average, much the same as for men. Proportionate mortality reduced the contrasts considerably but left the ranking of the regions little different except that, as before, Greater Londoia had a high proportion in terms of the deaths from all causes and Lancashire had a low proportion.
IVLAP INO.
March 1949
The change in the national death-rate in the ten years to I942-46 was a fall of 25 per cent, and for the regions it ranged from 17 per cent in North I to 32 per cent in the East. The present map would not differ appreciably from the one for I932-36 for women of this age period, Wales I and North I still showing very large excess, whilst tile Southern regions, the West Riding and the Eastern region have rates well below average. The county boroughs showed a decline in death-rate of about 22 per cent in the ten years, compared with 3o per cent in rural areas. Turning attention to the later working ages 45 to 65, the third map depicts tlle regional variation in respiratory tuberculosis deathrate in i932-36 amongst men of those ages. Highest rates were in Greater London and North IV, with 18 and 17 per cent excess over the national rate, followed by Midland I with 8 per cent, and Wales II and North III with only 2 per cent excess. North I and Wales I, strange to say, had mortalities IO per cent below average. The distribution differed considerably
o. ..........
o"
Morch 1949
TUBERCLE
59
from that for young adults, Greater London, fell by 34 per cent in the ten years, the North IV and North III ranking higher, amount of decrease ranging from ~5 per whilst North I and Wales I, instead of cent in Wales I to 45 per cent in Wales II, showing very large excess, had mortalities a fairly uniform improvement. Tile map for well below the national rate. The proportion- I942-46 would therefore be almost the ate mortality ranking was similar except that same as for 1932-36. The outstanding facts brought out by this North IV and I I I were below average. In the ten years following, the national are (I) the contrast between the regional rate fell by 9 per cent, all the regions showing distribution of male mortality from resa decline of this order except Wales I, with a piratory tuberculosis at ages 45 to 65 and small increase, North I, North II and Mid- the distributions for women of the same age land II with small decreases. Except for and young adults, particularly as regards Wales I the map for i942-46 would not Lotldon, North I, and Wales I; and (2) the curiously Iow death-rates in West Riding for differ appreciably from that for I932-36. The fourth map, for females aged 45 to 65, young adults and women aged 45 to 65 but is very different, Wales, North I and Mid- not for men of that age. Although the ordinary North-South gradland I all showing large excess in I932-36, whilst North III along with the South East ient of mortality to which we are accustomed had rates I6 per cent below average. is probably a gradient of fatality rather than Comparing this map with that for young of incidence, it seems almost certain that the adult females, there were no important two peculiarities I have mentioned are due differences in the regional ranking, whereas to incidence. That cannot be proved until the maps for males of the two age-groups we have regio~al morbidity statistics, and as yet I cannot give you ar,y. Tile notification showed pronounced contrasts. The national rate for women of 45 to 65 data for the last ten years are now at the General Register Office and are being worked upon.; and as soon as it is possible something will be published about notification rates in different parts of England and Wales. It must be said that the same difficulty about absence of local populadorts by sex and age since 1941 will be as great a handicap here as for deaths. However, it should be possible to get a series of rates for the years immediately before the war, another series for I947-48 based on the sex-age distributions at the end of 1947 which, as I have already said, we are hoping to have presently, and a third series based on the coming census.
MAPNo. 4.
Morbidity Statislics.--It has been said that notifications do not provide a good enough basis for morbidity rates. For finn-respiratory tuberculosis that is probably true, but I see no reason why llotL~cation statistics of pulmonary tuberculosis, if cautiously handled, cannot tell us a great deal about the epidemiology of the disease just as notifi-
60
TUBERCLE
March 1949
cations of other infectious diseases have done. namely that the patient is 'suffering from' H a d everyone waited for the day when pulmonary tuberculosis, is changed for typhoid, diphtheria, poliomyelitis, whooping- some other definition thought to be more cough, scarlet fever or measles wohld be scientific, the statistician m a y have to retire one h u n d r e d per cent notified before making from the field and wait. Substitution of a statistical studies of notifications, we should skiagraphic distinction between morbid and know a good deal less about epidemiology non-morbid for one based on assessment of today than we do. My personal view is that the whole patient would not necessarily be in the period between I925 and 1938 an progress. I do not wish to decry in any way opportunity was lost to find out a good deal the use of all possible means as aids to about the epidemiology of tuberculosis by diagnosis; but I do urge that a clinical means of the notification records in existence; diagnosis which takes into account all the and unless we are careful it may not come to facts provides the best possible basis for us again for a long time. We were then in a morbidity statistics, and that no attempt be period of comparative stability, when both made at present to change the criterion for the definition of what constitutes morbidity notification. No doubt some will object that in respect of pulmonary tuberculosis, and statistics are of minor importance compared the degree of completeness of its notification with other aspects of the problem, and that changed little. T h a t was reflected in the if there is a need to frame newdefinitions of remarkable constancy of the ratio between what constitutes pulmonary tuberculosis as a deaths and the notified cases amongst whom morbid condition, they should be framed they occurred, which remained about 5 ~ regardless of statistics. A warning of what per cent. The call-up for national service that may lead to has recently been given us which brought into the open many unnotified by happenings in the different zones of cases, and mass-radiography and tuberculin Germany. If a great drive is now to be made testing which conspired together to upset the to eradicate tuberculosis - and I hope it is dividing line between infection and illness, it is most necessary to safeguard the statistics changed that, and there is now a danger that or progress may appear to be in the opwe m a y for some time have no statistical posite direction to that hoped for. basis on which we can rely for measuring trends of morbidity. Effect on Life Expectalion.--In I931 Miss T h e notion that the substitution of K a r n published a paper in the 'Annals of definitions founded on the reading of Eugenics,' in which she showed by matheskiagrams coupled with tuberculin tests will matical calculations that the expectation of provide a better basis for morbidity statistics life at ages 2 to io in the years around 192I than the old criterion for notification is in my would have been two years greater if pulview quite unfounded. Recent studies in monary tuberculosis could then have been America of the reliability of skiagram diag- completely eliminated for all time. If cancer noses by the same observer reading the same could have been eliminated the correspondfilm at different times and by different ing increase would have been just under observers reading a film independently, one and a half years. For people who had suggest that statistics based on this criterion safely reached the age of 35 the salutary will be subject to larger errors than notifi- effect of eradicating pulmonary tuberculosis cation statistics. I a m looking at this question was to increase life expectation by one year, from the point of view of a statistician who is the effect of eliminating cancer being about concerned that we shall not throw away an one and a half years as at earlier ages. imperfect basis for statistics and try to T h a t calculation has not been repeated substitute another which is more imperfect. for any more recent period, but it has been I f the present criterion for notification, possible to make a much simpler calculation
March 1949
TUBERCLE
for I945 of the loss of future lifetime caused b y the deaths from respiratory tuberculosis which occurred in Englar~d and Wales in that year. The assumption here is that each individual saved from dying of that cause in 1945 would continue to be subject from that time on to the total death-rates of I945 in the same way as the other people comprising the life-table population 9 What is being measured, therefore, is the addition to the total years expected to be rived by the whole population of England and Wales after 1945 if all those who actually died of the disease in I945 lind instead been restored to normal health. It does not assume any eradication of tuberculosis after i 9 4 5 , and therein differs from Kam's assumption. Table V I I shows the total person-years of future lifetime lost on account of the deaths in the single year I945 from the four causes, respiratory tuberculosis, syphilitic diseases, cancer and accidents, with distinction of sex, and the average number &person-years lost per death. The total loss of future lifetime amongst persons of both sexes caused by the deaths in I945 amounted to 824,ooo personyears for tuberculosis, compared with
Cause of death in i945 Tuberculosis: Respiratory . . . . . . . . Other forms . . . . . . Syphilitic disease . . . . . . Cancer . . . . . . . . Accidents .. ....
Cause of death in I945 Tuberculosis: Respiratory . . . . . . Other forms .... Syphilitic disease .... Cancer . . . . . . . . Accidents . . . . . .
61
I,I02,5oo ibr cancer, 428,500 for accidents and 48,200 for syphilis. Table V I I I shows the loss of future lifetime between ages 15 to 65, that is to say, the loss of so-called working years, which gives a better picture of the effects of the four causes of death on the productive capacity of the population. The comparison with cancer is here very different, the loss of future person-years in the productive period of Iife being altogether 565,3oo as a result of tuberculosis deaths, but only 354,6oo as a result of cancer deaths and ~68,2oo through fatal accidents in I945. On the average a death from tuberculosis robs the community of 24 years of future working life between ages 15 and 65, wlxereas a cancer death causes a loss of only 5 years between those ages and a fatal accident 18 years9 I think this suffices to establish the statement that tuberculosis is our number one problem, in that its eradication would cox~fer more benefit to the community than would be the case for any other disease. It follows that the British Tuberculosis Association has a great and important work to do, and I wish it a full measure of success.
TABLE VII Total person-years of future life lost (thousands) Males Females 324.3 3~5 . r 9~ 94"3 3o'5 17'7 492"9 6o9'7 283"7 r46"7 Ta_~LE VIII No. of thousands of personyears or future life lost between ages 15 and 65 Males Females 213.8 64'8 i3. 5 I55"9 ~85"9
22i. 4 65"3 89 I98"7 82"3
No. of person-years lost per death Males Females 27.6 46"4 I8"4 I3"6 3 z'9
39'8 5~ 24'7 I6' 3 26'6
No. of such person-years lost per death Males Females ~8.2 33"4 8.o 4"3 2i-o
28.0 35 .2 ~2.o 5'3 T4"9
50
A Study of Tuberculosis Mortality in England and Wales* By PERCY STOCKS
Chief Medical Statistician, General Register Office Introduction. - If we have not reached the
point at which tuberculosis is the world's number one health problem, it would seem that we are rapidly approaching it, not so much because of an increase in the prevalence of the disease as because of the dethronement of other scourges by the discovery of means by which their ravages can be reduced very greatly. With the birth of the World Health Organization there now seems a reasonable prospect of pulling down malaria, venereal and some other diseases from their pedestals as killing agents. But we cannot yet say that of tuberculosis, over which the road to victory in the world-wide sense is going to be a tough and difficult one. The beginning of industrialization in many countries has been bringing with it an insidious spread of tuberculosis, and since we know as yet of no better prospect for them than what Dr Gilmour has called the 'long and painful process' of gaining some racial immunity, the countries of the East and some of our colonies are not in a h a p p y position. In India an estimate of some 289 million suffering from the disease with only a handful of tuberculosis officers to look after them brings the problem into startling perspective. Even in such an enlightened country as the United States of America we still see tuberculosis death-rates three times as high in the coloured population as in the white, and in New Zealand, Malaya and parts of Africa the racial contrast is considerably greater. Mortality Trends Over75 Years.- Looking at the more cheerful side of the picture, we see that in the United States the crude death-rate from tuberculosis amongst w h i t e males has fallen in thirty-five years since 1911 b y three-quarters and amongst white females by more than five-sixths, the present rates being about 4o. and 2o per lOO,OOO respec*An address given
to
tlvely. In England and Wales in the same period the crude rate for females has falletl to one-third of its 19I i value, and fig. I compares the downward trend of the rates for females in the two countries. Before the first world war U.S.A. had higher rates than ours; and during that war mortality increased in both countries, reaching peaks in the influenza year 1918. Then came a steep fall bringing the rates close together in 192o; but whereas the fall continued rapidly until 1921 in U.S.A., it was arrested TUBERCULOSIS (ALL FORMS) Female Death-Rates 1910-46 I~O -
CRUOE
--
US A (WHITE) CRUDE . . . .
r~"
\
,
15-
*~,+ ,+
SD-
" ..+
'1" ;"
~1"'~'l |~+IP +.
25-
01+910
" ~l-i
1~2.
.
.
.
Q ~IG,
;;+4.
.
.
.
.
I.
in 192o in England and Wales, with the result that U.S.A. showed a large advantage in I921 which has been maintained ever since. The disparity gradually increased fi'om about 17 per lO%OOO in I921 to about 25 in the early thirties and has averaged 22 in the last few years. The ratio between the two rates has changed much more markedly, from 82 per cent in 1921-23 to about 50 per cent in I944-46. T h e diagram shows also how great was the disturbance to the trend of female mortality from tuberculosis in the first world war compared with that in the second war. The effect of the second war on English women
the British Tuberculosis Association on November i9, i948.
March 1949
TUBERCLE
was little greater than what occurred in the first war amongst American women. From I933 onwards the dotted curve shows also the trend of standardized mortality, which has not fallen quite so much as the crude rate. The apparent improvement over the last I5 years is somewhat exaggerated by the crude death-rate for females, owing to the increasing proportion of older women in the population whose tuberculosis mortality is lower.
5f TUBERCULOSIS, RESPIRATORY--1875- [ 947 C.N.I. On Logarithmic Scale (Wars Omitted)
TUBERCULOSIS--ENGLAND AND WALES Comparative Mortality Indices (Persons) 1871-1947 ~
~
L,
ALL FIll1klS . . . . . ~ESPIRATO/~Y IBS.0
18'90
, I~O0
, ~10
--., t92o
, ~30
.., 1940
.. 19S0
Fzo. 3.
--
,
-,
r
F~o, ~.
Fig. 2 shows how the comparative mortality index for tuberculosis of both sexes together changed between I87I and i93o , this being indicated by the broken line. The continuous line, which shows the trend of the C.M.I. for respiratory tuberculosis of perscns, is drawn between quinquennial points up to I9z 3 and then by single years to I947. Each C.M.I. is based upon the year i938 as unit, so the coming together of the two curves does not mean that there was zero mortality from non-respiratory tuberculosis. The fact that the two curves passed through a common point both in i873 and 1929 shows that between those dates the relative improvement was the same for respiratory as for non-respiratory tuberculosis. During the first half of that period the respiratory index was improving more quicldy, and during the second half nonrespiratory gradually made up the lost ground. When tile points on the respiratory tuberculosis curve are plotted on a logarith-
mic scale, as in fig. 3, it is seen that the trend between 1875 and 191o foliowed almost an exact straight line, meaning that the percentage reduction in moztality in a unit of time was constar~t during the thirtyfive years, after smoothing out fluctuations due to cold winters, influenza and other temporary disturbances. After recovering from the first world war, the downward trend became slightIy steeper, with the result that in the period I931-39 the points were tklling more and more below where they would have been if the rate of improvement during I875-z9Io had continued without interruption. After the second setback in the early years of the second war, the rates ofi945, i946 and 1947 were again below the values expected if the steady fall of the thirty-five years before I9io had continued without change iia the thirty-five years. Despite setbacks, some progress in reducing mortality from respiratory tuberculosis has been m a d e during the last ten years. The crude death-rate in z936-37 was 565 per million. Ini938-39 it was down to 518, but continuing to calculate the rate on the total population ir~cluding all non-civilians, since rejection at recruitment and invaliding out of the tuberculous made the crude civiIian death-rates meaningless, the rate in I94o-4 I was back again at the same level as in
March 1949
TUBERCLE
52
i936-37. Then followed another sudden drop to about 503 in I94~-43, and a further fall in I944 to 474- The next two years brought small improvements, b u t in z947 the rate was 468, not much different from that of 1944 9 The comparative mortality index, being a civilian rate and greatly affected by selection owing to the high death-rate at the service ages, is not informative during z94o-46 , that is until demobilization was nearly completed, but we can usethlly compare the I947 index with the pre-war figures. The unit for this standardized index is the mortality of I938 , and both in I936 and z937 the index was just about x.I, whilst in I947 it was '93, an improvement of '5 per cent in the ten years. The crude death-rate based on total population showed , 7 per cent fall, so no great difference is m a d e by standardization for age. O f course if we compare I947 with the more favourable years ,938-39, the decrease does not look so good, being 7 per cent for the C.M.I. and ~o per cent for the crude rate in eight and a half years. Perhaps the fairest measure of the improvement during the last ten years is obtained b y comparing the C.M.I. for I947 with that for the five years centred at I937, which gives 13 per cent fall for respiratory tuberculosis. This ignores the t e m p o r a r y rise during the early part of the war. I f we start from , 8 5 , 55 and follow the comparative mortality index for the respiratory form to I931-35 at ten-year intervals the successive percentage falls were 9, **, x7, 2x, I9, x6, 2I, 24. It appears that the rate of improvement during the last ten years has been considerably less than that which occurred in Ages
any ten-year period between ,87z-75 and r93z-35. Death-rates by Sex and Age. - Turning now to the recent changes in mortality at various ages for each sex, I have set out in a series of tables the average rates of the last four periods of two years expressed as percentages of the average rate in I938-39 , using always totaI rates, including non-civilians both ia the deaths and populations. The base period I938-39 was a very favourable one, as [ have pointed out, but for the purpose of comparing the recent changes in different sex-age groups it is best to use the last two years before the influences of the war began to operate. For respiratory tuberculosis, the overall trend from I938-39 to I946-47 showed a fall of I ~ per cent in the crude rate at all ages and of 789 per cent in the comparative mortality index. In the tables the period I931-35 has also been inserted tO show what happened between then and I938-39. T a b l e I shows the trends for respiratory tuberculosis amongst boys and girls. All these rates were falling very rapidly between ' 9 3 I and z939, and then increased at the beginning of the war. For some reason for which I can offer no explanation tl~e deathrates amongst children under 5 have remained substantially above the level they reached in i938-39, and show no tendency to recover from the change which took place at the onset of war. The z946-47 level is about 4 ~ per cent above that of I938-39 , whereas if the pre-war trend had continued it would have been about 5 o per cent below. For boys aged 5 to io the
TABLE I 1940-4 z
1931-35
1938-39
194~-43
1944-45
1946-47
144 263 z6o
ioo zoo ioo
12o i7~ Io9
I~8
I~2
75
112 134 84
123 Iz6 65
~8o ~79 174
~oo zoo ioo
17o if2 ~23
17o 79 88
17o Io6 80
159 zo2 8z
Boyx O - -
9
,
--
,
.
io-x 5 Girls O - -
9
~ Io-15 --
~
B
W
m
a
e
9
, .
t
March 1949
TUBERCLE TABLE II 1940--41
Ages
1931-35
I938--39
I37 I38 I3I 133
,oo Ioo Ioo
II2 98 IO7
100
53
I94~-43
I944-45
I946-47
IIO
98 83 92 97
77 79 87 85
66 70 85 80
12o 112 I~ IO8
99 97 95 89
86 9t 9~ 87
80 92 97 85
Men i 5-
..
20-
..
25-
..
34-45
9
~
Women I N-
..
139
Ioo
20~
..
121
IO0
25-
..
1~ 7
Ioo
35-45
138
IOO
1938-39 rate was very low and it increased again greatly in 194o-41 , a n d although falling again it has not regained the best level attained before the war. For girls aged 5 to IO no substantial increase occurred, but the pre-war downward trend has been arrested. Amongst children aged i o to 15, however, present mortality is well below that of I938-39. Whether this unsatisfactory trend of death-rates from respiratory tuberculosis at ages under IO has anything to do with changes in diagnosis at these ages I do not know. At their face value the rates contrast strangely with recent trends o f child mortality from other diseases, a n d also with those for respiratory tuberculosis in females of every age over I o. Table II shows the trend of mortality since 1931-35 amongst young adults between 15 and 45. Their rates were declining in the decade before the war quite rapidly for each sex and age group, though not so quicldy for women between 2o and 35 as the others. The I931-35
Ages
I938-39
fall was broken in 194o-41 , but had already been resumed by 1942-43, and has continued since then for most of the groups, though more slowly than in the pre-war years. Amongst men under 25, however, the decline in death-rate between I938 and 1947 has been almost as great as if the war had not intervened. Women aged 25-35, on the other hand, show little improvement since 1938-39. Table I I I shows the trend of rates for m e n and women of various ages over 45. Here there is a great contrast between men and women. Mortality of women between 45 and 65 was only slightly raised in I94O-4I, and the downward trend was quickly resumed, improvement since i938-39 being about one-fifth9 At 65 to 75 the fall has amounted to 8 per cent, and at higher ages the war did not interrupt the decline9 Amongst men of 45 to 55 the rate has fallen IO per cent since I938-39 , but at 55 to 75 rates are now higher than they were even in 1931-35 and show no sign of improving. At ages over 75 the death-rate
TABLE I I I I94o-4I
I942-43
I944-45
I946-47
Men
45-- 9149 55-- 9 65-- . .
'' "' 9149
75 a n d o v e r
119 IO~ IO9
IO0 IO0 IO0
IO5 I13 IIO
99 IO 7 IO9
92 104 I16
9~ IO5 120
122
IOO
IR2
I32
i31
135
I37 I29 i3o ii6
ioo ioo Ioo IOO
iOl Io4 io 7 92
Women
45- 9149 ., 55- .9 ., 65- .9 .. 75 and over
88 9~ 92 87
8I 79 91 79
76 8I 92 86
54
March 1949
TUBERCLE
has increased b y one-third since i938-39 , and is also above that of i931-35. T h e contrast between recent trends of mortality from respiratory tuberculosis in men over 55 and other sections of the adult population is very pronounced, and it will be noted that the decline between 1931 a n d 1939 was small for men aged 55 to 75 compared with all other groups. T h e reason for this contrast is not clear. It is easy to say it is due to more complete certification of what was previously called bronchitis, and that it is due to more frequer~t use o f x-rays, but w o m e n of ages over 55 would also be affected b y these factors, and their rates have fallen. A more likely explanatioll is that the men who are now aged 55 to 80 bore the brunt of the first world war, and at the same time lost a considerable fraction of their fittest members; and in the second world war m a n y of the same men were again subjected to heavy strains of another kind. Fig. 4 shows how great a change has occurred in the age distributior~ of male death-rates as a result of the continued downward trend amongst young men and upward trend amongst older men. In ~85I-6O the age period of maximal male death-rate was 2o to 25; in 186I-9o it was 35 to 45; from 1891 until I938 it was 45 to 55, but from 1938 onwards the peak has been at ages 55 to 65. In the United States of America the present peak of mortality is at 65 to 75 for white males and at 45 to 55 for non-white males. It must be remembered that a graph of death-rates experienced at successive ages by a " c o h o r t " ofmales born at a given time would differ greatly from fig. 4, owing to the progressively improving conditions they encountered as age advanced. For females the story has been different. In I 8 5 I - 9 o the age period of maximal death-rate was 25 to 3 5 ; ir~ I891-I9IO it had progressed to 35 to 45, b u t in I 9 1 I - 2 o it moved back to ~o to 35, and since then it has been at ages 2o to 25. In the United States there are now two maxima for white
RESPIRATORY TUBERCULOSIS--ENGLAND AND WALES Death-Rates by Sex and Age in 1931-35 and 1947 !5C
. A
;/ "\',
0,.' *....
:OO
/ ':~,
\X
f! : :l, ' ' , ~
', '\ d /
:'\
50
9
i.r ', g
0 tO
20
30
10
50
60
70
LtO
Fro. 4.
females, one at 25 to 35 and the other at 75 and over, the first being a slight hill rather than a peak; but for non-white females there is still a sharp peak at 20 to ~5 similar to that for English women. T h e vcry different bchaviour of male and female death-rates in the last ten years cannot be explained in a facile way by x-rays or fashions in death certification; they are a continuation of a process which has been going on for a long time, but which seems to have b e e n intensified in recent years. T h e death-rates of children from nonrespiratory tuberculosis were declining by about 4o per cent every ten years in the period between the wars. The average rates of 1946 and I947 are compared with the average rates of 1936-37 in Table IV. Boys and gifts show 35 and 39 per certt improvement respectively at ages under 5, 32 and 15 per cent at 5 to lO, and 16 and 13 per cent at IO to 15. The war has retarded the rate of falI at the school ages, though not for younger children.
Regional D eath-rates.--Let us now look at another aspect, namely the rcgionaI differences between death-rates from respiratory
March 1949
TUBERCLE
55
TABLE I V
Boys oA v e r a g e a n n u a l rates p e r million living: z936-37 . . . . . . 476 1938-39 . . . . . . 431 I946-47 . . . . . 308 P e r c e n t a g e decrease in I946-47 c o m p a r e d with: i936-37 rate . . . . --35 I938-39 rate . . . . --29
Girls
5-
to-z5
o-
5-
zo-15
r64 I42 i12
1o6 9r 89
418 383 256
135 128 iI 5
1oo 97 87
--3 ~ --2I
--16 -- ~
--39 --33
--15 --io
--13 --Io
TABLE V.--REsPIRATORY TUBERCULOSIS AT AGES I5--45 R e g i o n a l d e a t h - r a t e s in i 9 3 ~ - 3 6 p e r cent of n a t i o n a l rate 9 P r o p o r t i o n a t e mortalities~ b a s e d on all non-violent causes, per c e n t o f n a t i o n a l p r o p o r t i o n , I 9 3 2 - 3 6 a n d i942-46. E s t i m a t e d p e r c e n t a g e changes in d e a t h - r a t e from those of I 9 3 2 - 3 6 to those of I94.0-46 (civilians).
Relative proportionate mortality Relative death-rate
Regions (in order of i932-36 death-rate)
i93~-36
1942-46 z93~-36
(civilians)
Percentage change in death-rate
Males .aged 15-45 North I . . . . Wales I .. Wales II .. North IV .. North II Greater London Midland I R e m a i n d e r of'S'outh East Midland II . . . . South West . . . . North III . . . . East . . . . . . C o u n t y boroughs .. O t h e r u r b a n districts R u r a l districts ..
9
9
i3i i~i zo8 Io7 io 3 Io 3 1oo 91 89 86 86 84
Io 9 io 3 ioi 93 lOO III 99 io 7 98 99 86 Io5
zo6 ioi io 4 93 99 III 1~ Io2 9~ 98 84 90
+ i + 3 + 7 + 4 -1- 3 + 4 +z2 o ~ -F 3 -F --I,
i~ 4 9~ 73
io8 94 88
io6 94 85
+ + +
I56 I37 I33 Iz5 Io5 ioi 99 96 92 87 84 83
II 3 Io6 Io8 IO4 Io4 92 lOO io2 io8 97 8~ 98
II 7 II6 99 Io7 Io3 95 95 9I Io7 94 86 93
--2~ --I 7 --3z --23
ii6 96 87
~o6 94 89
rio 94 83
--22 --25 --3o
2 4 2
Females aged z5-45 Wales I .. North I .. Wales II .. North II .. Midland I .. North IV .. Midland II .. East Greater London S o u t h West .. North III R e m a i n d e r of'S'outh East C o u n t y boroughs .. O t h e r u r b a n districts R u r a l districts ..
.. 9.
--2 5
--23 --29 --32 --25 - 27 --~: - ~8
56
TUBERCLE
tuberculosis at two age-periods 15 to 45 and 45 to 65 for each sex. The estimation of death rates at particular age-groups in parts of England and Wales h a s been rendered difficult by two factors, the absence of a census in I94X and the great movements of population caused by the war. Although the GeneraI l~egister Office has kept track of the movements of people of all ages combined by means of the National Register, and also since I944 of children under 5 and 5 to 15 b y means of their special ration books, we have not found it practicable to keep statistics of the sex-age distribution of the adult movements. T o help us in repairing this gap, we had a count made by sex and age of the maintenance registers of the National Register in every area of the country at the end of I947. It is expected that the results, when they have been tested in every possible way, will be m a d e generally available. Meanwhile, the only way we can estimate deathrates in regions at ages z5 to 45 and 45 to 65 by sex during z942-46 is by an indirect method based on proportionate mortality, involving certain assumptions as to what happened to the total death-rates from all non-violent causes. What I have tried to do is first to give a picture of the regional death-rates from respiratory tuberculosis for the four sex-age groups during the five-year period 1932-36, based on tolerably good population estimates for that period; and then estimate the percentage changes in death-rates which occurred in the ten-year interval from I93~-36 to I942-46. This was done by crossing a bridge from absolute death-rates to proportionate mortalities based on deaths from all non-violent causes in i932-36 , and then recrossing a parallel bridge fi~om the known proportionate mortalities of civilians in I942-46 to the unknown absolute deathrates of civilians. The assumptions ilavolved were (I) that recruitment for the Services affected mortality in the regions equally and (~) that when the death-rate at a given age from all non-violent causes changed in
March 1949
England and Wales as a whole, it changed in the same proportion within each region. The constancy of regional rates from all causes in terms of the national rate of the same period before the war made the second assumption a reasonable one, and although the resulting percentage changes in tuberculosis death-rates in the ten years, shown in Tables V and VI, can only be regarded as approximations, they are very unlikely to be wide of the mark for any region. (For Table V I see opposite page.) T h e first map shows the death-rates of males aged 15 to 45 from respiratory tuberculosis in the regions during r932-36 expressed as percentages of the national rate. Absence of any shading means less than 8o; open horizontal lines mean 8o to 89, close horizontal lines 9o to 99, cross-hatching Ioo to Io 9 and black means I Io or over. North I and Wales I were black, with 3 z and eI per cent excess; North II and IV, Wales II and Greater London showed small excess; Midland I was just average, and the
Map No. T.
March 1949
57
TUBERCLs
TABLE VI.---I{EsPIRATORu TUBERCULOSIS Regional death-rates in i982-36 per cent of national rate. on all non-violent causes, per cent of national proportion, percentage changes in death-rate from those of r932-36
Relative proportionate mortality
Relative death-rate
Regions (in order of i932-36 death-rate)
I98~-36
AT ACES 4 5 - 6 5 Proportionate mortalities, based I93~-36 and I942-46. Estimated to those of I942-46 (civilians).
I94~-46 I932-36
(civilians)
Percentage change in death-rate
Malaaged 45-65 Greater London .. North IV Midland I Wales I I North I I I North II North I Wales I Remainder of South East Midland I I . . . . South West . . . . East . . . . . . County boroughs .. Other urban districts Rural districts ..
II8 II7 m8
II8 99 Io9
93 9o 90 84 83 74 66
98 94 88 8I 98 92 84 8o
II6 97 iII 97 9~ 99 96 91 96 96 84 84
to2
mo
I3I 8i 59
II3 84 75
II3 87 76
- 9 -- 5 -- 7
I39 I25 m4 m2 IO7 I~ 97 97 95 89 84 84
I25 Io7 IO3 I~ 3 IO7 99 85 IO8 Io3 97 97 75
lO5 99 II7 I24 96 98 84 ~I 9 94 94 98 69
--45 --39 --25 --34 --4I --35 --35 --28 --4 ~ --36 --33 --40
122 88 85
1m 87 89
ZiG 88 85
--85 --34 --37
io2
0
9
a
0
.. ..
--IO --to -- 7 --~ --11
3 --I- 3
--
--If
-- 4 -- 8 -- 5
Females aged 45-65 Wales I I .. North I Wales I Midland I Midland II North I I North IV Greater London South West .. East Remainder of South East North I I I .... County boroughs . . . . . . . Other urban districts .... Rural districts . . . . . .
9. .. 9. .. 9. 9. 9. .. 9. 9. 9. ..
rest of the Midlands, East and South had rates 9 to 16 per cent below average. The most curious feature was North I I I , the West Riding, with a rate 14 per cent below average. W h e n expressed as proportionate mortalities irt terms of that of E n g l a n d and Wales the order was changed considerably, Greater L o n d o n r a n k i n g highest and North I V (Lancashire and Cheshire) rankir~g quite low. The reason for t h a t was that a l t h o u g h these regions had very similar
tuberculosis death-rates, N o r t h I V h a d a m u c h higher death-rate from all other causes than had Greater Lortdon. H o w e v e r , the West R i d i n g ranked lowest a m o n g s t the regions for proportionate mortality in 1 9 3 2 . 36, and this was again true irt I 9 4 2 - 4 6 . The only regions showing a n y substantial change in p r o p o r t i o n a t e mortality in 194~-46 were M i d l a n d I where it increased, a n d the East where it decreased. T h e change in the national d e a t h - r a t e in
TUBERCLE
58
the ten years to z 942-46 for men of this age group was a rise of 4 per cent, the increase being accounted for b y the high degree of civilian selection of men of these ages in the war period for tuberculosis. The only regions showing appreciable variation from the average change were Midland I with a rise of I~ per cent, East with a fall of II per cent and M i d l a n d II with a fall of 2 per cent. North I I I maintained its low position. The second m a p shows the position in i932-36 for females aged 15 to 45. Again the highest rates were in Wales I and North I, with 56 and 37 per cent excess, Wales II following closely with 33 per cent excess, and then North II with 15 and Midland I with 5 per cent. The Southern regions and North I I I had low rates, that of the West Riding being I6 per cent below average, much the same as for men. Proportionate mortality reduced the contrasts considerably but left the ranking of the regions little different except that, as before, Greater Londoia had a high proportion in terms of the deaths from all causes and Lancashire had a low proportion.
IVLAP INO.
March 1949
The change in the national death-rate in the ten years to I942-46 was a fall of 25 per cent, and for the regions it ranged from 17 per cent in North I to 32 per cent in the East. The present map would not differ appreciably from the one for I932-36 for women of this age period, Wales I and North I still showing very large excess, whilst tile Southern regions, the West Riding and the Eastern region have rates well below average. The county boroughs showed a decline in death-rate of about 22 per cent in the ten years, compared with 3o per cent in rural areas. Turning attention to the later working ages 45 to 65, the third map depicts tlle regional variation in respiratory tuberculosis deathrate in i932-36 amongst men of those ages. Highest rates were in Greater London and North IV, with 18 and 17 per cent excess over the national rate, followed by Midland I with 8 per cent, and Wales II and North III with only 2 per cent excess. North I and Wales I, strange to say, had mortalities IO per cent below average. The distribution differed considerably
o. ..........
o"
Morch 1949
TUBERCLE
59
from that for young adults, Greater London, fell by 34 per cent in the ten years, the North IV and North III ranking higher, amount of decrease ranging from ~5 per whilst North I and Wales I, instead of cent in Wales I to 45 per cent in Wales II, showing very large excess, had mortalities a fairly uniform improvement. Tile map for well below the national rate. The proportion- I942-46 would therefore be almost the ate mortality ranking was similar except that same as for 1932-36. The outstanding facts brought out by this North IV and I I I were below average. In the ten years following, the national are (I) the contrast between the regional rate fell by 9 per cent, all the regions showing distribution of male mortality from resa decline of this order except Wales I, with a piratory tuberculosis at ages 45 to 65 and small increase, North I, North II and Mid- the distributions for women of the same age land II with small decreases. Except for and young adults, particularly as regards Wales I the map for i942-46 would not Lotldon, North I, and Wales I; and (2) the curiously Iow death-rates in West Riding for differ appreciably from that for I932-36. The fourth map, for females aged 45 to 65, young adults and women aged 45 to 65 but is very different, Wales, North I and Mid- not for men of that age. Although the ordinary North-South gradland I all showing large excess in I932-36, whilst North III along with the South East ient of mortality to which we are accustomed had rates I6 per cent below average. is probably a gradient of fatality rather than Comparing this map with that for young of incidence, it seems almost certain that the adult females, there were no important two peculiarities I have mentioned are due differences in the regional ranking, whereas to incidence. That cannot be proved until the maps for males of the two age-groups we have regio~al morbidity statistics, and as yet I cannot give you ar,y. Tile notification showed pronounced contrasts. The national rate for women of 45 to 65 data for the last ten years are now at the General Register Office and are being worked upon.; and as soon as it is possible something will be published about notification rates in different parts of England and Wales. It must be said that the same difficulty about absence of local populadorts by sex and age since 1941 will be as great a handicap here as for deaths. However, it should be possible to get a series of rates for the years immediately before the war, another series for I947-48 based on the sex-age distributions at the end of 1947 which, as I have already said, we are hoping to have presently, and a third series based on the coming census.
MAPNo. 4.
Morbidity Statislics.--It has been said that notifications do not provide a good enough basis for morbidity rates. For finn-respiratory tuberculosis that is probably true, but I see no reason why llotL~cation statistics of pulmonary tuberculosis, if cautiously handled, cannot tell us a great deal about the epidemiology of the disease just as notifi-
60
TUBERCLE
March 1949
cations of other infectious diseases have done. namely that the patient is 'suffering from' H a d everyone waited for the day when pulmonary tuberculosis, is changed for typhoid, diphtheria, poliomyelitis, whooping- some other definition thought to be more cough, scarlet fever or measles wohld be scientific, the statistician m a y have to retire one h u n d r e d per cent notified before making from the field and wait. Substitution of a statistical studies of notifications, we should skiagraphic distinction between morbid and know a good deal less about epidemiology non-morbid for one based on assessment of today than we do. My personal view is that the whole patient would not necessarily be in the period between I925 and 1938 an progress. I do not wish to decry in any way opportunity was lost to find out a good deal the use of all possible means as aids to about the epidemiology of tuberculosis by diagnosis; but I do urge that a clinical means of the notification records in existence; diagnosis which takes into account all the and unless we are careful it may not come to facts provides the best possible basis for us again for a long time. We were then in a morbidity statistics, and that no attempt be period of comparative stability, when both made at present to change the criterion for the definition of what constitutes morbidity notification. No doubt some will object that in respect of pulmonary tuberculosis, and statistics are of minor importance compared the degree of completeness of its notification with other aspects of the problem, and that changed little. T h a t was reflected in the if there is a need to frame newdefinitions of remarkable constancy of the ratio between what constitutes pulmonary tuberculosis as a deaths and the notified cases amongst whom morbid condition, they should be framed they occurred, which remained about 5 ~ regardless of statistics. A warning of what per cent. The call-up for national service that may lead to has recently been given us which brought into the open many unnotified by happenings in the different zones of cases, and mass-radiography and tuberculin Germany. If a great drive is now to be made testing which conspired together to upset the to eradicate tuberculosis - and I hope it is dividing line between infection and illness, it is most necessary to safeguard the statistics changed that, and there is now a danger that or progress may appear to be in the opwe m a y for some time have no statistical posite direction to that hoped for. basis on which we can rely for measuring trends of morbidity. Effect on Life Expectalion.--In I931 Miss T h e notion that the substitution of K a r n published a paper in the 'Annals of definitions founded on the reading of Eugenics,' in which she showed by matheskiagrams coupled with tuberculin tests will matical calculations that the expectation of provide a better basis for morbidity statistics life at ages 2 to io in the years around 192I than the old criterion for notification is in my would have been two years greater if pulview quite unfounded. Recent studies in monary tuberculosis could then have been America of the reliability of skiagram diag- completely eliminated for all time. If cancer noses by the same observer reading the same could have been eliminated the correspondfilm at different times and by different ing increase would have been just under observers reading a film independently, one and a half years. For people who had suggest that statistics based on this criterion safely reached the age of 35 the salutary will be subject to larger errors than notifi- effect of eradicating pulmonary tuberculosis cation statistics. I a m looking at this question was to increase life expectation by one year, from the point of view of a statistician who is the effect of eliminating cancer being about concerned that we shall not throw away an one and a half years as at earlier ages. imperfect basis for statistics and try to T h a t calculation has not been repeated substitute another which is more imperfect. for any more recent period, but it has been I f the present criterion for notification, possible to make a much simpler calculation
March 1949
TUBERCLE
for I945 of the loss of future lifetime caused b y the deaths from respiratory tuberculosis which occurred in Englar~d and Wales in that year. The assumption here is that each individual saved from dying of that cause in 1945 would continue to be subject from that time on to the total death-rates of I945 in the same way as the other people comprising the life-table population 9 What is being measured, therefore, is the addition to the total years expected to be rived by the whole population of England and Wales after 1945 if all those who actually died of the disease in I945 lind instead been restored to normal health. It does not assume any eradication of tuberculosis after i 9 4 5 , and therein differs from Kam's assumption. Table V I I shows the total person-years of future lifetime lost on account of the deaths in the single year I945 from the four causes, respiratory tuberculosis, syphilitic diseases, cancer and accidents, with distinction of sex, and the average number &person-years lost per death. The total loss of future lifetime amongst persons of both sexes caused by the deaths in I945 amounted to 824,ooo personyears for tuberculosis, compared with
Cause of death in i945 Tuberculosis: Respiratory . . . . . . . . Other forms . . . . . . Syphilitic disease . . . . . . Cancer . . . . . . . . Accidents .. ....
Cause of death in I945 Tuberculosis: Respiratory . . . . . . Other forms .... Syphilitic disease .... Cancer . . . . . . . . Accidents . . . . . .
61
I,I02,5oo ibr cancer, 428,500 for accidents and 48,200 for syphilis. Table V I I I shows the loss of future lifetime between ages 15 to 65, that is to say, the loss of so-called working years, which gives a better picture of the effects of the four causes of death on the productive capacity of the population. The comparison with cancer is here very different, the loss of future person-years in the productive period of Iife being altogether 565,3oo as a result of tuberculosis deaths, but only 354,6oo as a result of cancer deaths and ~68,2oo through fatal accidents in I945. On the average a death from tuberculosis robs the community of 24 years of future working life between ages 15 and 65, wlxereas a cancer death causes a loss of only 5 years between those ages and a fatal accident 18 years9 I think this suffices to establish the statement that tuberculosis is our number one problem, in that its eradication would cox~fer more benefit to the community than would be the case for any other disease. It follows that the British Tuberculosis Association has a great and important work to do, and I wish it a full measure of success.
TABLE VII Total person-years of future life lost (thousands) Males Females 324.3 3~5 . r 9~ 94"3 3o'5 17'7 492"9 6o9'7 283"7 r46"7 Ta_~LE VIII No. of thousands of personyears or future life lost between ages 15 and 65 Males Females 213.8 64'8 i3. 5 I55"9 ~85"9
22i. 4 65"3 89 I98"7 82"3
No. of person-years lost per death Males Females 27.6 46"4 I8"4 I3"6 3 z'9
39'8 5~ 24'7 I6' 3 26'6
No. of such person-years lost per death Males Females ~8.2 33"4 8.o 4"3 2i-o
28.0 35 .2 ~2.o 5'3 T4"9