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Mortality of goitrous and non-goitrous subjects—A follow-up study
PubL lftth, Lond. (1980) 94, 21 !-214
Mortality of Goitrous and Non<3oitrous Subjects --A Follow-up Study M. L.
Burr
M.D., M.F.C.K~.. D.P.H.
A. S. St. Leger M.B.. M.Sc., F .S.S.
and I. T. Benjamin
Medical Research Council, Epidemiology Unit (South Wales), 4 Richmond Road, Cardiff CF2 3AS
A follow-up study was undertaken to compare the mortality of 145 goitrous subjects with 145 matched controls, all of whom had been identified in a survey over 20 years previously. The goitrous subjects did not suffer any excess mortality from isehaemic hearl disease or from all causes of death. Introduetion TIwroid disorders are common ha some parts o f Great Britain. A recent survey in-Coutlty Dudlam showed Ithat 6.9% of the local population had obvious goitres, l It is believed that endemic goitre in Britain causes much ill-health? This is not easily measured, however, and il is not clear whether goitre is really an important public health problem. The opportuniW was therefore taken to see whether the presence or history of thyroid disease in a population that was surveyed for goitre 20 years ago has been associated with any increased mortality subsequently.
Methods In 1955 a survey was conducted in the Vale o f Glamorgan in which 95% of the defined population were interviewed. 3 The subjects were asked whether they'had suffered from goitre, and all those who said they had, or who appeared to have a goitre, were subsequently examined by a physician with a special interest in thyroid disease. The goitrous subjects were matched individually by age and sen with controls who were examined by the same physician and confirmed as non-goitrous. ~ In 1978 a follow-up study was undertaken to discover whether each subject w.as alive or dead. Causes of death were obtained from the death certificates o f all those wixo had died.
Results The original pairs comprised 21 men and 1 24 women with current or previous goitre, together with matched controls who were adjusted to be free from thyroid abnormality by the examining physician. His classification o f the goitrous subjects is shown in Table 1. 0038-3506/80/040211 +04 $01.00/0
©1980 The Society of Community Medicine
M. L. Burr et al
212
TABLE 1. Thyroid abnormalities in goitrous subjects Men Type of goitre
Number
Large benign Small benign Definitely loxie Probably loxie Probably not to xic ltistory of benign goitre not now palpable Totals
Women Mean Age*
Number
Mean Age*
9 8 0 2 1 1
59"2 63"4 52-5 81 "0 79"0
27 35 12 6 16 28
57-9 47-9 40-1 54'2 49. ! 54"2
21
62"1
124
51 "2
*Ages in completed years on 31 December 1955. I n 1978 i n f o r m a t i o n was obtained a b o u t all these subjects, and a c o p y o f t h e death certificate was inspected for every subject wl~o had died. Table 2 shows the mortality in goitrous and nongoitrous subjects over the 23 year period, together with t h e mean ages at d e a t h . There is no significant difference between cases and controls in their mortality o r their ages a t death.
TABLE 2. Deaths in goitrous and non-goitrous subjects Number of suhjecls Goitrous men Control men Goitrous women Control women
Number of deaths
21 21 124 124
Age atdeath (mean *--S.E.)
14 14 51 47
75-0 +- 3-2 76-i -l+ .1"8 73-5 ¥ I "4 75.0 - 1"6
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
,..,
,,
J
TA tILE 3. Causes of death in goitrous and non-goitrous subjects
Cause of death Neoplastic disease lschaemie heart disease Cerebrovascular disease Other cardiovascular diseases Respiratory diseases All other diseases Totals
ICD code (8th revision) 'I40 - 239 410 - 414 430 - 438 Other conditions 390 - 458 460 - 519
Men Goitres Controls
Women Goitres Conlrols
All subjects Goitres Controls
0 3
5 0
7 16
5 26
7 19
10 26
2
3
12
3
14
6
4 1 4
6 0 0
5 5 6
4 5 4
9 6 I0
t0 5 4
14
14
51
47
65
61
Table 3 shows the deaths classified b y cause. No deaths were directly attributable to t h y r o i d disease or thyroid t u m o u r . In o n e case colloid goitre was reported in Part 2 o f the death certificate, i.e. as contributing to the death b u t n o t related t o the disease o r condition causing it. This was a man w h o died o f b r o n c h o p n e u m o n i a due to a perforated gastric ulcer.
213
Mortality o f Goitreus arnl Non-goitrous sub]ects TABLE 4. Mortality in women with benign goitre and controls (allowing for pair-matching) ConSols ALive
Dead
All
Cases Dead
28
17
45
Alive All
16 44
45 62
61 105
In order to examine the mortality associated with different kinds o f goitre two groupings were used, benign (including "probably not toxic") and toxic ("probably" and "'def'mitety"). The mortality among women with benign goitre and controls is summarized in Table 4. Analysis, allowing for the matching o f cases and controls, gives a relative risk. among the cases o f 1-1 which does not differ significantlyefrom I-0. Division o f the sample into those born before and those born in and after 1900 does not alter tiffs result.
TABLE 5. Mortality in men with benign goitre and controls (allowing for pail matching) Controls Alive
Dead
All
Ca~l~s
Dead Alive All
I0
2
12
3 13
4 6
7 19
The mortality among men with benign goitre is similarly shown in Table 5. The relative risk is 0-7 and is not significantly different from 1-0. The numbers in this table are too small for further subdivision. Among cases of toxic goitre two men and six women had died compared with one man and three women in the controls. These numbers are insufficient for statistical analysis. Discussion In 1955 the prevalence o f goitre was fairly high in the Vale o f Glamorgan. About 3% of women were found to have a I~rge goitre, and lesser abnormalities were very common. Follow-up of patients with non-toxic goit~e has shown that such people have an increased risk o f developing thyrotoxicosis, s Furthermore, thyroid function is an important determinant o f cholesterol metabolism so that minor thyroid abnormalities could play a part in the causation of ischaemic heart disease. It therefore seemed worthwlule to follow up these pairs of subjects with and without thyroid abnormalities to see whether the possession o f a goitre was associated with any increase in mortality. It is obvious that survival over the 23 years since the survey was not affected by the initial thyroid status of the subjects. A benign goitre in particular seemed to confer no excess risk o f
214
AI. L. Burr et al
death; numbers o f deaths in the toxic gtoup were too small for definite conclusions to be drawn. There was no tendency for goitrous subjects to die at a younger age than file non-goitrous subjects. The mortality from ischaemic heart disease was no higher in the goitrous group;in fact, more o f the non-goitrous subjects died from this ,cause. The other obvious difference in the mortality of the two groups is in respect of cerebrovascular disease, o f which 12 goitrous women died compared with 3 controls. It seems that this difference, like that in ischaemic heart disease mortality, is attributable to an unusual distribution of deaths in the control group. In 1972 among women aged 7 0 - 7 9 , 26% o f all dentils in England and Wales we.re atl~ibutable to ischaemic heart disease and I9% to cerebrovascular disease.6 The corresponding figures for ~:he goitrous subjects were 31% and 24%, whereas in the control group the proportions were 55% and 6%. Thus the difference between the two groups is presumably an artefact due to unusual proportional mortality rates in the non-goitrous subjects.
References
I. 2. 3. 4. 5. 6.
Tunbridge, W. M. G., Evered, D. C., Hall, R., Appleton, D., Brewis, M., Clark, F., Evans, J. G., Young, E., Bird, T. & Smith, P. A. (1977). The spectrum of thyroid disease in a community; the Whickham Survey. Clinical ~ndocrinology 7, 4 8 1 - 9 3 . Montgomery, D. A. D. & Welboume, R. B. (1975). Medical and Surgical Endocrinology. London: Edward Arnold. Coehrane, A. L., Miall, W. E. & Clarke, W. G. (1956). Results o f a chest X-ray survey in the Vale of Glamorgan: a study o f an agricultural community. Tubercle 37, 4 1 7 - 2 5 . Trotter, W. R., Cochrane, A. L., Benjamin, I. T., Miatl, W. E. & Exley, D. (1962). A goitre survey in the Vale of Glamorgan. British Journal o f Preventi.ue and Social Medich~e 16, 16-2I. lngbar, S. H. & Woeber, K. A. (1968). The thyroid gland In Textbook o f Endocrinology. R. H. Williams (Ed) Philadelphia: W. S. Saunders Company. Office of Population Censuses and Surveys (1974) . The Registrar General's Statistical R e v i e w o f England and Wales f o r the Year 1972. Part I. Tables, Medical. London: H.M.S.O.
Mortality of Goitrous and Non<3oitrous Subjects --A Follow-up Study M. L.
Burr
M.D., M.F.C.K~.. D.P.H.
A. S. St. Leger M.B.. M.Sc., F .S.S.
and I. T. Benjamin
Medical Research Council, Epidemiology Unit (South Wales), 4 Richmond Road, Cardiff CF2 3AS
A follow-up study was undertaken to compare the mortality of 145 goitrous subjects with 145 matched controls, all of whom had been identified in a survey over 20 years previously. The goitrous subjects did not suffer any excess mortality from isehaemic hearl disease or from all causes of death. Introduetion TIwroid disorders are common ha some parts o f Great Britain. A recent survey in-Coutlty Dudlam showed Ithat 6.9% of the local population had obvious goitres, l It is believed that endemic goitre in Britain causes much ill-health? This is not easily measured, however, and il is not clear whether goitre is really an important public health problem. The opportuniW was therefore taken to see whether the presence or history of thyroid disease in a population that was surveyed for goitre 20 years ago has been associated with any increased mortality subsequently.
Methods In 1955 a survey was conducted in the Vale o f Glamorgan in which 95% of the defined population were interviewed. 3 The subjects were asked whether they'had suffered from goitre, and all those who said they had, or who appeared to have a goitre, were subsequently examined by a physician with a special interest in thyroid disease. The goitrous subjects were matched individually by age and sen with controls who were examined by the same physician and confirmed as non-goitrous. ~ In 1978 a follow-up study was undertaken to discover whether each subject w.as alive or dead. Causes of death were obtained from the death certificates o f all those wixo had died.
Results The original pairs comprised 21 men and 1 24 women with current or previous goitre, together with matched controls who were adjusted to be free from thyroid abnormality by the examining physician. His classification o f the goitrous subjects is shown in Table 1. 0038-3506/80/040211 +04 $01.00/0
©1980 The Society of Community Medicine
M. L. Burr et al
212
TABLE 1. Thyroid abnormalities in goitrous subjects Men Type of goitre
Number
Large benign Small benign Definitely loxie Probably loxie Probably not to xic ltistory of benign goitre not now palpable Totals
Women Mean Age*
Number
Mean Age*
9 8 0 2 1 1
59"2 63"4 52-5 81 "0 79"0
27 35 12 6 16 28
57-9 47-9 40-1 54'2 49. ! 54"2
21
62"1
124
51 "2
*Ages in completed years on 31 December 1955. I n 1978 i n f o r m a t i o n was obtained a b o u t all these subjects, and a c o p y o f t h e death certificate was inspected for every subject wl~o had died. Table 2 shows the mortality in goitrous and nongoitrous subjects over the 23 year period, together with t h e mean ages at d e a t h . There is no significant difference between cases and controls in their mortality o r their ages a t death.
TABLE 2. Deaths in goitrous and non-goitrous subjects Number of suhjecls Goitrous men Control men Goitrous women Control women
Number of deaths
21 21 124 124
Age atdeath (mean *--S.E.)
14 14 51 47
75-0 +- 3-2 76-i -l+ .1"8 73-5 ¥ I "4 75.0 - 1"6
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
,..,
,,
J
TA tILE 3. Causes of death in goitrous and non-goitrous subjects
Cause of death Neoplastic disease lschaemie heart disease Cerebrovascular disease Other cardiovascular diseases Respiratory diseases All other diseases Totals
ICD code (8th revision) 'I40 - 239 410 - 414 430 - 438 Other conditions 390 - 458 460 - 519
Men Goitres Controls
Women Goitres Conlrols
All subjects Goitres Controls
0 3
5 0
7 16
5 26
7 19
10 26
2
3
12
3
14
6
4 1 4
6 0 0
5 5 6
4 5 4
9 6 I0
t0 5 4
14
14
51
47
65
61
Table 3 shows the deaths classified b y cause. No deaths were directly attributable to t h y r o i d disease or thyroid t u m o u r . In o n e case colloid goitre was reported in Part 2 o f the death certificate, i.e. as contributing to the death b u t n o t related t o the disease o r condition causing it. This was a man w h o died o f b r o n c h o p n e u m o n i a due to a perforated gastric ulcer.
213
Mortality o f Goitreus arnl Non-goitrous sub]ects TABLE 4. Mortality in women with benign goitre and controls (allowing for pair-matching) ConSols ALive
Dead
All
Cases Dead
28
17
45
Alive All
16 44
45 62
61 105
In order to examine the mortality associated with different kinds o f goitre two groupings were used, benign (including "probably not toxic") and toxic ("probably" and "'def'mitety"). The mortality among women with benign goitre and controls is summarized in Table 4. Analysis, allowing for the matching o f cases and controls, gives a relative risk. among the cases o f 1-1 which does not differ significantlyefrom I-0. Division o f the sample into those born before and those born in and after 1900 does not alter tiffs result.
TABLE 5. Mortality in men with benign goitre and controls (allowing for pail matching) Controls Alive
Dead
All
Ca~l~s
Dead Alive All
I0
2
12
3 13
4 6
7 19
The mortality among men with benign goitre is similarly shown in Table 5. The relative risk is 0-7 and is not significantly different from 1-0. The numbers in this table are too small for further subdivision. Among cases of toxic goitre two men and six women had died compared with one man and three women in the controls. These numbers are insufficient for statistical analysis. Discussion In 1955 the prevalence o f goitre was fairly high in the Vale o f Glamorgan. About 3% of women were found to have a I~rge goitre, and lesser abnormalities were very common. Follow-up of patients with non-toxic goit~e has shown that such people have an increased risk o f developing thyrotoxicosis, s Furthermore, thyroid function is an important determinant o f cholesterol metabolism so that minor thyroid abnormalities could play a part in the causation of ischaemic heart disease. It therefore seemed worthwlule to follow up these pairs of subjects with and without thyroid abnormalities to see whether the possession o f a goitre was associated with any increase in mortality. It is obvious that survival over the 23 years since the survey was not affected by the initial thyroid status of the subjects. A benign goitre in particular seemed to confer no excess risk o f
214
AI. L. Burr et al
death; numbers o f deaths in the toxic gtoup were too small for definite conclusions to be drawn. There was no tendency for goitrous subjects to die at a younger age than file non-goitrous subjects. The mortality from ischaemic heart disease was no higher in the goitrous group;in fact, more o f the non-goitrous subjects died from this ,cause. The other obvious difference in the mortality of the two groups is in respect of cerebrovascular disease, o f which 12 goitrous women died compared with 3 controls. It seems that this difference, like that in ischaemic heart disease mortality, is attributable to an unusual distribution of deaths in the control group. In 1972 among women aged 7 0 - 7 9 , 26% o f all dentils in England and Wales we.re atl~ibutable to ischaemic heart disease and I9% to cerebrovascular disease.6 The corresponding figures for ~:he goitrous subjects were 31% and 24%, whereas in the control group the proportions were 55% and 6%. Thus the difference between the two groups is presumably an artefact due to unusual proportional mortality rates in the non-goitrous subjects.
References
I. 2. 3. 4. 5. 6.
Tunbridge, W. M. G., Evered, D. C., Hall, R., Appleton, D., Brewis, M., Clark, F., Evans, J. G., Young, E., Bird, T. & Smith, P. A. (1977). The spectrum of thyroid disease in a community; the Whickham Survey. Clinical ~ndocrinology 7, 4 8 1 - 9 3 . Montgomery, D. A. D. & Welboume, R. B. (1975). Medical and Surgical Endocrinology. London: Edward Arnold. Coehrane, A. L., Miall, W. E. & Clarke, W. G. (1956). Results o f a chest X-ray survey in the Vale of Glamorgan: a study o f an agricultural community. Tubercle 37, 4 1 7 - 2 5 . Trotter, W. R., Cochrane, A. L., Benjamin, I. T., Miatl, W. E. & Exley, D. (1962). A goitre survey in the Vale of Glamorgan. British Journal o f Preventi.ue and Social Medich~e 16, 16-2I. lngbar, S. H. & Woeber, K. A. (1968). The thyroid gland In Textbook o f Endocrinology. R. H. Williams (Ed) Philadelphia: W. S. Saunders Company. Office of Population Censuses and Surveys (1974) . The Registrar General's Statistical R e v i e w o f England and Wales f o r the Year 1972. Part I. Tables, Medical. London: H.M.S.O.