Journal of Psychosomatic Research, Vol. 19, pp. 273 to 278. Pergamon Press, 1975. Printed in Great Britain
LIFE CHANGE PATTERNS PRIOR TO DEATH IN ISCHAEMIC HEART DISEASE. A STUDY ON DEATH-DISCORDANT TWINS” DE FAIRE ULF (Received 2 May 1975)
IN RECENTyears several studies have demonstrated that essential changes in the psychosocial situation may precede various manifestations of ischaemic heart disease (IHD) such as myocardial infarction [l-2] and sudden death [3]. It has been suggested [4-51 that a psychosocial change could trigger the development of a myocardial infarction. However, the meaning of such a change is closely connected with the personality of the individual [5]. Studies by Rosenman and Friedman [6-81 have shown that men with a certain personality or behavior pattern (labelled Behavior Pattern Type A and characterized by excessive sense of time urgency, enhanced aggressiveness and competitive drive) were significantly associated with an increased prevalence and incidence of IHD. These personality traits are probably partly inherited [6]. The question now arises whether the psychosocial changes reported prior to the onset of various IHD catastrophes [l-3] simply reflect a certain behavior pattern or whether the life changes may be independent risk factors for IHD. The difficulty inherent in such questions may be illustrated by a quotation from BiGrck 191:“some of the difficulties in the study of environment, as separated from the genetic equipment, derive from the fact that a certain environment may be a factor of selection attracting those with a certain kind of genes; or those with a certain genetic equipment may favor, and therefore seek, a special environment. Thus, a mutual interaction between the two factors does occur”. Therefore, studies on twins could be of great interest with regard to psychosocial factors and IHD because it would be possible to control the hereditary influence. Monozygotic (MZ) and dizygotic (DZ) twins probably also share environmental factors to a higher degree than other subjects. METHODS Subjects The present study derives from the Swedish Twin Registry, which was set up in the years 19591961. The compilation procedure and demographic structure of the twin series have been described by CederlSf [lo]. During 1971-1973, 262 twin pairs aged 46-70 yr, became death discordant, i.e. one of the members of an unbroken pair died during the period, and 205 of the surviving co-twins (108 males and 97 females) were examined with regard to IHD and its risk factors [ll]. Among 108 male death-discordant pairs, the cause of death had been attributed to IHD (myocardial infarction and/or sudden death) in 40 cases (10 MZ, 25 DZ and 5 of unknown zygosity). The causes of death had been established from all pertinent information, e.g. hospital records, autopsy protocols in 86 % and death certificates in 14% [ll]. In the present study, life changes have been analysed in 27 (9 MZ and 18 DZ) of the 35 male pairs of known zygosity, death discordant with respect to IHD. Incomplete answers made it necessary to exclude the other 8 pairs (1 MZ and 7 DZ). Variables The surviving co-twins were carefully examined on average 5 months after the death of the partner [ll]. At the time of the examination they were also interviewed, using a questionnaire with 35 items *From the Medicinska kliniken, Serafimerlasarettet, 273
Box 12700, 112 83 Stockholm, Sweden.
274
DE FAIRE ULF
about life changes. Information about the deceased twins was obtained through relatives, usually their wives, by means of the same questionnaire, which was checked later on the telephone by the interviewer. The questions were based on a Swedish version of the Schedule of Recent Events (SRE) questionTABLE l.---LIFE
CHANGE SCORES ACCORDING TO A MALE CONTROL SAMPLE OF 84 MEN, 44-65 yr OF AGE
Items
1.
Death
of spouse
2.
Being
fired
3.
Death of close family
4.
Detention
5.
Divorce
6.
Uajor
7.
Uarriage
8.
Foreclosure
93
from work
78
change
in health
Death
of close friend
Major
change
13.
Change
to a different
14.
Change
in living
member
71 45 61
loan
from work
60
with boss
15.
Sexual
16.
Major
17. 18.
Outstanding
56
in financial
55
state
55
line of work
55
conditions.
52
difficulties change
personal
Mortgage
or loan more
Addition
of family
21.
In-law
22.
Son or daughter
in working in residence
IJajor change
52
in work responsibility
19. 20.
Major
for family
70
12.
Change
of or worry
on mortgngeor
11.
Troubles
23.
19 78
9. 10.
?4* 2 5‘.
member
in jail
Retirenent
Change
85
52
achievement than 10000 Sm. crowns
in number
of arguments
nith
spouse
46 46
troubles
business
51 50
member
leaving
home
conditions
43 41
readjustment
26.
Xortgage
27.
Change
28.
17ife starts
29.
Kinor
30.
Change
in recreation
31.
Change
in sleeping
32.
Change
in number
33.
Change
in eating habits
34.
Change
in social
35.
Vacation
or loan less then 10000 SW. crowns
in personal
40 39
habits
38
or stops work
violations
46 45
37
of the lam
35 33
habits
of family
activities
get-togethers
30 31 32 27
Life change patterns prior to death in ischaemic heart disease
275
naire, worked out by Holmes and Rahe [12]. New life changes were reported for each 6-month period during the 4 yr prior to the death of the partner. Each new life change had been scored (in life change units, LCU) by a control material of 84 men, 44-65 years of age 1131(Table 1). The sum of all LCU reported by a twin for a 6-month period gives his LCU total for that period. Mean 6-monthly LCU totals are then calculated for various subgroups of subjects. RESULTS Figures 1 and 2 present mean 6-monthly LCU totals for both deceased MZ and DZ twins and their surviving co-twins. The deceased twins consistently displayed higher scores than their surviving MZ
I
I
4
FIG.
I
2 dlscordonce
3 Year prior to “death
I ”
1
x Deceased partner 0 Surwing
i
I
’
4
partner
I
I
3 Year
prior to.“death
I
I
2 discordance”
I
I
FIG. 2 MZ
DZ
Standard error
pco.05
N.S.
FIG. 3
276
DE FAIRE ULF
partners, the difference being somewhat more pronounced for the MZ pairs. However, the differences were non-significant for all of the 6-monthly periods (paired one-tailed t-test). The LCU totals gradually increased throughout the 4-yr period for both deceased and surviving twins. For the deceased twins, the totals were highest during the last 6 months before death, when they amounted to about 100 for the MZ individuals and about 80 for the DZ. The sum of all LCU reported by a twin over the whole 4-yr period gives his LCU total for that period (Fig. 3). The mean of the 4-yr LCU totals was significantly higher for the deceased MZ twins than for their surviving partners (p < 0.05). The corresponding difference for the DZ pairs was not significant. The changes which seemed to discriminate best between the deceased and the surviving co-twins were those associated with employment. DISCUSSION
The results of this twin study may indicate that important life changes can characterize the total psychosocial situation during the last years prior to death in IHD. These findings are in accordance with earlier reports on life changes in relation to the onset of various IHD catastrophes [l-3]. The conclusions must be drawn with some caution because the material is relatively small and the technique retrospective. Another source of uncertainty lies in the use of relatives (usually the wife) as informants about the deceased subjects life changes. However, Theorell has compared the life changes reported by 20 Swedish male hospital patients with the changes reported on their behalf by their wives, and he found no significant differences in the total LCU scores [13]. The technique of using relatives as informants has been employed by Rahe and Lind in their study on psychosocial factors and sudden cardiac death in 39 subjects. In the group of deaths not preceded by serious illness during the last 3 yr, the subjects’ life change intensities during the final 6 months were three times greater than in chronologically identical periods 2 and 3 yr prior to death, whereas those whose death had followed episodes of serious illness had had a more gradual build-up. In the present study, the deceased twins had had a gradual build-up of life change intensity during the 4 yr prior to death. A smaller, but similar, increase was seen among the surviving co-twins. These findings may be explained by the fact that episodes of serious illness during the 4 yr prior to the time of death discordance were distributed in a random fashion among the deceased and surviving partners. The relatively high levels observed in the surviving partners could be due in part to the tendency for the partners in a twin pair to have similar social circumstances. In a recent critical analysis of various papers employing SRE, Wershow and Reinhart [14] state that the relationships found in many studies between illness and life changes are weak. They pointed out that some people become ill without any discernible life changes and that others may find constructive ways of dealing with change. They also believe that we need to know more about such coping mechanisms in order to find out how to prevent disease. In a recent retrospective study, Lundberg et al. [15] suggested that the SRE may be used for predicting MI in the near future if the subjects themselves rate the relative importance of their own recent life changes. So far, life change observations have been confirmed only in retrospective studies but data from an ongoing prospective study on 9000 men in Stockholm [16] indicate that “life change totals for the last year” were not able to discriminate near-future MI victims from the rest of the population. The only “change variable” with sigat work during the last nificant discriminative power was “increased responsibility year”. In the present study, too, changes associated with employment seemed to discriminate best between deceased and surviving co-twins.
Life change patterns prior to death in ischaemic heart disease
277
In another study on 91 male twin pairs [17], “dedication to work” was recorded significantly more often among the MZ twins who had had myocardial infarction than among their healthy MZ partners. In the infarction-discordant DZ pairs, however, there was no such difference. It is interesting that in this study, too, complete genetic matching was required to reveal factors associated with IHD. From the results of his twin study, Liljefors [17] concluded that “given a certain constitution, the disease may be aggravated or elicited by remote environmental factors. Some of these factors would seem to be closely linked to the individual’s attitude to his work”. The finding that the affected twins among the infarction-discordant MZ pairs were dedicated to work to a significantly greater extent than their partners [17] is in agreement with a characteristic of coronary-prone individuals according to Friedman and Rosenman [6]. These personality traits were, however, considered to be due in part to genetic factors. The psycho social factors seem to interact in a complex way and when analysing the pre-infarct situation it seems advisable to subdivide them into predisposing and precipitating [9, 181. Besides the well-known predisposing risk factors high serum cholesterol, high blood pressure and cigarette smoking, this category includes type A behavior. Precipitating factors, on the other hand, may strike suddenly or occur as a gradual build-up of life changes before the onset of serious disease. Such changes may be closely connected with the personality of the patient [5]. Therefore one cannot rule out the possibility that a selective factor is involved in the association between a build-up of serious life changes and the onset of myocardial infarction [l-2] and sudden death [3]. However, to judge from the present results, life changes-especially those connected with work situations-may characterize the total psychosocial situation during the last years before death in IHD even when genetic factors are kept under control. SUMMARY Life change patterns have been analysed in 27 male twin pairs, death discordant with respect to IHD. The LCU totals gradually increased throughout the 4-yr period prior to death discordance for both deceased and surviving twins. The deceased twins, however, consistently displayed higher scores than their surviving partners. The mean of the 4-yr LCU totals was significantly higher for the deceased MZ twins than for their surviving partners (p < 0.05), whereas the corresponding difference for the DZ pairs was not significant. It is concluded that these results indicate that life changesespecially those connected with work situations-may characterize the total psychosocial situation during the last years before death in IHD even when genetic factors are kept under control. investigation was supported by grants from the Swedish National Association against Heart and Chest Diseases, the Swedish Medical Research Council and the American Medical Association, Education and Research Foundation. Acknowledgements-This
REFERENCES R. H. and PAASIKIVIJ. Psychosocial factors and myocardial infarction. II: An outpatient study in Sweden. J. Psychosom. Res. l&33 (1971). 2. THEORELL T. and RAHE R. H. Psychosocial factors and myocardial infarction. I: An inpatient study in Sweden. J. Psychosom. Res. 15,25 (1971). 3. RAHB R. H. and LIND E. Psychosocial factors and myocardial sudden death in Sweden. J. Psychosom. Res. 15, 19 (1971). 4. WOLFF H. G. Stress and Disease. Thomas, Springfield (1952). 5. H~NKLEL. E., CHRISTENSON W. N., KANE F. D., OSTFELDA., THETFORDW. N. and WOLFF H. G. 1.
RAHE
An investigation of the relation between life experience, personality characteristics, susceptibility to illness. Psychosom. Med. 20,278 (1958).
and general
278
DE FAIRE ULF
6. FRIEDMANM. and ROSENMAN R. H. Association of specific overt behavior pattern with blood and cardiovascular findings. JAMA 169, 1286 (1959). 7. ROSENMANR. H., FRIEDMANM., STRAUSSR., WURM M., JENKINSC. D. and MESSINGERH. B. Coronary heart disease in the Western Collaborative Group Study: A folow-up experience of two years. JAMA 195, 86 (1966). 8. ROSENMANR. H., FRIEDMANM., STRAUSR., JENKINSC. D., ZYZANSKIS. J. and WURM M. Coronary heart disease in the Western Collaborative Group Study: A follow-up experience of 43 years. J. Chron. Dis. 23, 173 (1970). 9. BI~RCK G. Environment and disorders of the circulatory system. Bull. N.Y. Acad. Med. 35, 3 (1959). 10. CEDERL~F R. The Twin Method in Epidemiological Studies on Chronic Disease. Karolinska Institutet (1966). 11. DE FAIRE U. Ischaemic heart disease in death discordant twins. A study on 205 male and female pairs. Acta Med. Scund. Suppl. 568 (1974). 12. HOLMEST. H. and RAHE R. H. The social readjustment rating scale. J. Psychosom. Res. 11,213 (1967). 13. THEORELLT. Psychosocial factors in relation to the onset of myocardial infarction and to some metabolic variables-a pilot study. Academic Thesis. Karolinska Institute (1970). view. J. Psychosom. 14. WER~HOWH. J. and REINHARTG. Life change and hospitalization-heretical Res. 18, 393 (1974). 15. LUNDBERGU., THEORELLT. and LIND E. Life changes and myocardial infarction: Individual differences in life change scaling. J. Psychosom. Res. 19, 27 (1975). 16. THEORELLT., LIND E. and FLODERUSB. The psychosocial situation before death and serious illness in middleaged men-a prospective study with special reference to myocardial infarction. Paper presented at the psychosomatic conference in Hong-Kong, March 1975. 17. LILJEFORSI. Coronary heart disease in male twins. Hereditary and environmental factors in concordant and discordant pairs. Acta Med. Stand. Suppl. 511,11970). 18. BIGRCKG. Contrasting Concepts of Ischaemic Heart Disease. The 1974 Lilly lecutures given in Oxford and London. Almqvist & Wiksell, Stockholm (1975).
LIFE CHANGE PATTERNS PRIOR TO DEATH IN ISCHAEMIC HEART DISEASE. A STUDY ON DEATH-DISCORDANT TWINS” DE FAIRE ULF (Received 2 May 1975)
IN RECENTyears several studies have demonstrated that essential changes in the psychosocial situation may precede various manifestations of ischaemic heart disease (IHD) such as myocardial infarction [l-2] and sudden death [3]. It has been suggested [4-51 that a psychosocial change could trigger the development of a myocardial infarction. However, the meaning of such a change is closely connected with the personality of the individual [5]. Studies by Rosenman and Friedman [6-81 have shown that men with a certain personality or behavior pattern (labelled Behavior Pattern Type A and characterized by excessive sense of time urgency, enhanced aggressiveness and competitive drive) were significantly associated with an increased prevalence and incidence of IHD. These personality traits are probably partly inherited [6]. The question now arises whether the psychosocial changes reported prior to the onset of various IHD catastrophes [l-3] simply reflect a certain behavior pattern or whether the life changes may be independent risk factors for IHD. The difficulty inherent in such questions may be illustrated by a quotation from BiGrck 191:“some of the difficulties in the study of environment, as separated from the genetic equipment, derive from the fact that a certain environment may be a factor of selection attracting those with a certain kind of genes; or those with a certain genetic equipment may favor, and therefore seek, a special environment. Thus, a mutual interaction between the two factors does occur”. Therefore, studies on twins could be of great interest with regard to psychosocial factors and IHD because it would be possible to control the hereditary influence. Monozygotic (MZ) and dizygotic (DZ) twins probably also share environmental factors to a higher degree than other subjects. METHODS Subjects The present study derives from the Swedish Twin Registry, which was set up in the years 19591961. The compilation procedure and demographic structure of the twin series have been described by CederlSf [lo]. During 1971-1973, 262 twin pairs aged 46-70 yr, became death discordant, i.e. one of the members of an unbroken pair died during the period, and 205 of the surviving co-twins (108 males and 97 females) were examined with regard to IHD and its risk factors [ll]. Among 108 male death-discordant pairs, the cause of death had been attributed to IHD (myocardial infarction and/or sudden death) in 40 cases (10 MZ, 25 DZ and 5 of unknown zygosity). The causes of death had been established from all pertinent information, e.g. hospital records, autopsy protocols in 86 % and death certificates in 14% [ll]. In the present study, life changes have been analysed in 27 (9 MZ and 18 DZ) of the 35 male pairs of known zygosity, death discordant with respect to IHD. Incomplete answers made it necessary to exclude the other 8 pairs (1 MZ and 7 DZ). Variables The surviving co-twins were carefully examined on average 5 months after the death of the partner [ll]. At the time of the examination they were also interviewed, using a questionnaire with 35 items *From the Medicinska kliniken, Serafimerlasarettet, 273
Box 12700, 112 83 Stockholm, Sweden.
274
DE FAIRE ULF
about life changes. Information about the deceased twins was obtained through relatives, usually their wives, by means of the same questionnaire, which was checked later on the telephone by the interviewer. The questions were based on a Swedish version of the Schedule of Recent Events (SRE) questionTABLE l.---LIFE
CHANGE SCORES ACCORDING TO A MALE CONTROL SAMPLE OF 84 MEN, 44-65 yr OF AGE
Items
1.
Death
of spouse
2.
Being
fired
3.
Death of close family
4.
Detention
5.
Divorce
6.
Uajor
7.
Uarriage
8.
Foreclosure
93
from work
78
change
in health
Death
of close friend
Major
change
13.
Change
to a different
14.
Change
in living
member
71 45 61
loan
from work
60
with boss
15.
Sexual
16.
Major
17. 18.
Outstanding
56
in financial
55
state
55
line of work
55
conditions.
52
difficulties change
personal
Mortgage
or loan more
Addition
of family
21.
In-law
22.
Son or daughter
in working in residence
IJajor change
52
in work responsibility
19. 20.
Major
for family
70
12.
Change
of or worry
on mortgngeor
11.
Troubles
23.
19 78
9. 10.
?4* 2 5‘.
member
in jail
Retirenent
Change
85
52
achievement than 10000 Sm. crowns
in number
of arguments
nith
spouse
46 46
troubles
business
51 50
member
leaving
home
conditions
43 41
readjustment
26.
Xortgage
27.
Change
28.
17ife starts
29.
Kinor
30.
Change
in recreation
31.
Change
in sleeping
32.
Change
in number
33.
Change
in eating habits
34.
Change
in social
35.
Vacation
or loan less then 10000 SW. crowns
in personal
40 39
habits
38
or stops work
violations
46 45
37
of the lam
35 33
habits
of family
activities
get-togethers
30 31 32 27
Life change patterns prior to death in ischaemic heart disease
275
naire, worked out by Holmes and Rahe [12]. New life changes were reported for each 6-month period during the 4 yr prior to the death of the partner. Each new life change had been scored (in life change units, LCU) by a control material of 84 men, 44-65 years of age 1131(Table 1). The sum of all LCU reported by a twin for a 6-month period gives his LCU total for that period. Mean 6-monthly LCU totals are then calculated for various subgroups of subjects. RESULTS Figures 1 and 2 present mean 6-monthly LCU totals for both deceased MZ and DZ twins and their surviving co-twins. The deceased twins consistently displayed higher scores than their surviving MZ
I
I
4
FIG.
I
2 dlscordonce
3 Year prior to “death
I ”
1
x Deceased partner 0 Surwing
i
I
’
4
partner
I
I
3 Year
prior to.“death
I
I
2 discordance”
I
I
FIG. 2 MZ
DZ
Standard error
pco.05
N.S.
FIG. 3
276
DE FAIRE ULF
partners, the difference being somewhat more pronounced for the MZ pairs. However, the differences were non-significant for all of the 6-monthly periods (paired one-tailed t-test). The LCU totals gradually increased throughout the 4-yr period for both deceased and surviving twins. For the deceased twins, the totals were highest during the last 6 months before death, when they amounted to about 100 for the MZ individuals and about 80 for the DZ. The sum of all LCU reported by a twin over the whole 4-yr period gives his LCU total for that period (Fig. 3). The mean of the 4-yr LCU totals was significantly higher for the deceased MZ twins than for their surviving partners (p < 0.05). The corresponding difference for the DZ pairs was not significant. The changes which seemed to discriminate best between the deceased and the surviving co-twins were those associated with employment. DISCUSSION
The results of this twin study may indicate that important life changes can characterize the total psychosocial situation during the last years prior to death in IHD. These findings are in accordance with earlier reports on life changes in relation to the onset of various IHD catastrophes [l-3]. The conclusions must be drawn with some caution because the material is relatively small and the technique retrospective. Another source of uncertainty lies in the use of relatives (usually the wife) as informants about the deceased subjects life changes. However, Theorell has compared the life changes reported by 20 Swedish male hospital patients with the changes reported on their behalf by their wives, and he found no significant differences in the total LCU scores [13]. The technique of using relatives as informants has been employed by Rahe and Lind in their study on psychosocial factors and sudden cardiac death in 39 subjects. In the group of deaths not preceded by serious illness during the last 3 yr, the subjects’ life change intensities during the final 6 months were three times greater than in chronologically identical periods 2 and 3 yr prior to death, whereas those whose death had followed episodes of serious illness had had a more gradual build-up. In the present study, the deceased twins had had a gradual build-up of life change intensity during the 4 yr prior to death. A smaller, but similar, increase was seen among the surviving co-twins. These findings may be explained by the fact that episodes of serious illness during the 4 yr prior to the time of death discordance were distributed in a random fashion among the deceased and surviving partners. The relatively high levels observed in the surviving partners could be due in part to the tendency for the partners in a twin pair to have similar social circumstances. In a recent critical analysis of various papers employing SRE, Wershow and Reinhart [14] state that the relationships found in many studies between illness and life changes are weak. They pointed out that some people become ill without any discernible life changes and that others may find constructive ways of dealing with change. They also believe that we need to know more about such coping mechanisms in order to find out how to prevent disease. In a recent retrospective study, Lundberg et al. [15] suggested that the SRE may be used for predicting MI in the near future if the subjects themselves rate the relative importance of their own recent life changes. So far, life change observations have been confirmed only in retrospective studies but data from an ongoing prospective study on 9000 men in Stockholm [16] indicate that “life change totals for the last year” were not able to discriminate near-future MI victims from the rest of the population. The only “change variable” with sigat work during the last nificant discriminative power was “increased responsibility year”. In the present study, too, changes associated with employment seemed to discriminate best between deceased and surviving co-twins.
Life change patterns prior to death in ischaemic heart disease
277
In another study on 91 male twin pairs [17], “dedication to work” was recorded significantly more often among the MZ twins who had had myocardial infarction than among their healthy MZ partners. In the infarction-discordant DZ pairs, however, there was no such difference. It is interesting that in this study, too, complete genetic matching was required to reveal factors associated with IHD. From the results of his twin study, Liljefors [17] concluded that “given a certain constitution, the disease may be aggravated or elicited by remote environmental factors. Some of these factors would seem to be closely linked to the individual’s attitude to his work”. The finding that the affected twins among the infarction-discordant MZ pairs were dedicated to work to a significantly greater extent than their partners [17] is in agreement with a characteristic of coronary-prone individuals according to Friedman and Rosenman [6]. These personality traits were, however, considered to be due in part to genetic factors. The psycho social factors seem to interact in a complex way and when analysing the pre-infarct situation it seems advisable to subdivide them into predisposing and precipitating [9, 181. Besides the well-known predisposing risk factors high serum cholesterol, high blood pressure and cigarette smoking, this category includes type A behavior. Precipitating factors, on the other hand, may strike suddenly or occur as a gradual build-up of life changes before the onset of serious disease. Such changes may be closely connected with the personality of the patient [5]. Therefore one cannot rule out the possibility that a selective factor is involved in the association between a build-up of serious life changes and the onset of myocardial infarction [l-2] and sudden death [3]. However, to judge from the present results, life changes-especially those connected with work situations-may characterize the total psychosocial situation during the last years before death in IHD even when genetic factors are kept under control. SUMMARY Life change patterns have been analysed in 27 male twin pairs, death discordant with respect to IHD. The LCU totals gradually increased throughout the 4-yr period prior to death discordance for both deceased and surviving twins. The deceased twins, however, consistently displayed higher scores than their surviving partners. The mean of the 4-yr LCU totals was significantly higher for the deceased MZ twins than for their surviving partners (p < 0.05), whereas the corresponding difference for the DZ pairs was not significant. It is concluded that these results indicate that life changesespecially those connected with work situations-may characterize the total psychosocial situation during the last years before death in IHD even when genetic factors are kept under control. investigation was supported by grants from the Swedish National Association against Heart and Chest Diseases, the Swedish Medical Research Council and the American Medical Association, Education and Research Foundation. Acknowledgements-This
REFERENCES R. H. and PAASIKIVIJ. Psychosocial factors and myocardial infarction. II: An outpatient study in Sweden. J. Psychosom. Res. l&33 (1971). 2. THEORELL T. and RAHE R. H. Psychosocial factors and myocardial infarction. I: An inpatient study in Sweden. J. Psychosom. Res. 15,25 (1971). 3. RAHB R. H. and LIND E. Psychosocial factors and myocardial sudden death in Sweden. J. Psychosom. Res. 15, 19 (1971). 4. WOLFF H. G. Stress and Disease. Thomas, Springfield (1952). 5. H~NKLEL. E., CHRISTENSON W. N., KANE F. D., OSTFELDA., THETFORDW. N. and WOLFF H. G. 1.
RAHE
An investigation of the relation between life experience, personality characteristics, susceptibility to illness. Psychosom. Med. 20,278 (1958).
and general
278
DE FAIRE ULF
6. FRIEDMANM. and ROSENMAN R. H. Association of specific overt behavior pattern with blood and cardiovascular findings. JAMA 169, 1286 (1959). 7. ROSENMANR. H., FRIEDMANM., STRAUSSR., WURM M., JENKINSC. D. and MESSINGERH. B. Coronary heart disease in the Western Collaborative Group Study: A folow-up experience of two years. JAMA 195, 86 (1966). 8. ROSENMANR. H., FRIEDMANM., STRAUSR., JENKINSC. D., ZYZANSKIS. J. and WURM M. Coronary heart disease in the Western Collaborative Group Study: A follow-up experience of 43 years. J. Chron. Dis. 23, 173 (1970). 9. BI~RCK G. Environment and disorders of the circulatory system. Bull. N.Y. Acad. Med. 35, 3 (1959). 10. CEDERL~F R. The Twin Method in Epidemiological Studies on Chronic Disease. Karolinska Institutet (1966). 11. DE FAIRE U. Ischaemic heart disease in death discordant twins. A study on 205 male and female pairs. Acta Med. Scund. Suppl. 568 (1974). 12. HOLMEST. H. and RAHE R. H. The social readjustment rating scale. J. Psychosom. Res. 11,213 (1967). 13. THEORELLT. Psychosocial factors in relation to the onset of myocardial infarction and to some metabolic variables-a pilot study. Academic Thesis. Karolinska Institute (1970). view. J. Psychosom. 14. WER~HOWH. J. and REINHARTG. Life change and hospitalization-heretical Res. 18, 393 (1974). 15. LUNDBERGU., THEORELLT. and LIND E. Life changes and myocardial infarction: Individual differences in life change scaling. J. Psychosom. Res. 19, 27 (1975). 16. THEORELLT., LIND E. and FLODERUSB. The psychosocial situation before death and serious illness in middleaged men-a prospective study with special reference to myocardial infarction. Paper presented at the psychosomatic conference in Hong-Kong, March 1975. 17. LILJEFORSI. Coronary heart disease in male twins. Hereditary and environmental factors in concordant and discordant pairs. Acta Med. Stand. Suppl. 511,11970). 18. BIGRCKG. Contrasting Concepts of Ischaemic Heart Disease. The 1974 Lilly lecutures given in Oxford and London. Almqvist & Wiksell, Stockholm (1975).
