Journal of Psychosomatic Research, Vol. 23, pp. 219 to 223. Pergamon Press Ltd. 1979. Printed in Great Britain.
TYPE-A BEHAVIOUR IN PATIENTS WITH NON-CORONARY CHEST PAIN ADMITTED TO A CORONARY CARE UNIT S. AHNVE,*
U. DE FAIRE,* K. ORTH-GOM~R*
and T.
THEORELL*
(Received 20 February 1979) Abstract-The present study is focused on the behaviour of 23 men admitted to a coronary care unit for suspected acute myocardial infarction and turned out not to suffer from ischaemic heart disease even at a follow-up 2-4 years later (OBS-group). These patients are compared with 34 infarction patients and 43 healthy control subjects. For evaluation of Type-A behaviour a self administered ‘Adjective check-list’ was used. The mean score from that list was significantly elevated in the OBSgroup as compared both with the infarction group (p < 0.02) and the control group (p < 0.001). No difference was obtained between the two latter groups. It is concluded that Type-A behaviour may be a common feature among persons with non-coronary chest pain, admitted to a coronary care unit.
TYPE-A
BEHAVIOUR
is characterized
by ambitious,
obsessive
and
impatient
striving
and has been associated with elevated risk of developing ischaemic heart disease (IHD) in middle-aged men [l]. It is questionable, however, whether this type of
behaviour is specific for the coronary prone person [2]. Some investigations have tried to identify behaviour characteristics specific for other disorders. For instance, longlasting gastritis and duodenal ulcer have been associated with irritability, also as a feature of pattern A behaviour, in a prospective study of middle-age men [3]. A study previously published from this hospital indicated that ‘inability to relax during leisure’ was associated with a relatively short delay from onset of chest pain to admittance to a coronary care unit (CCU), [4]. The aim of the present study was to investigate the behaviour of patients who are admitted to a CCU for suspected acute myocardial infarction (AMI) due to central chest pain, and turned out not to suffer from IHD even at a follow-up 2-4 years later [5]. These subjects have been compared with patients who did suffer from myocardial infarction and with healthy control subjects.
MATERIAL During the period 1 June 1972 to 15 May 1974, 59 men without a previous history of IHD (i.e. angina pectoris or myocardial infarction) were admitted to the CCU because of central chest pain, and turned out not to have AM1 [5]. By the time of the follow-up 2-4 years later there were 47 men still alive and willing to participate. Twenty-three of these 47 were I 65 years of age at that time and they constituted the observation group (OBS-group). The infarction group consisted of 34 men i 65 years of age with a history of AM1 2-4 years earlier. They were selected from the out-patient clinic during the follow-up period in 1976. Forty-three healthy men were also examined and used as controls (control group). They were randomly chosen from the payroll of three large enterprises in the Stockholm area: LM Ericson, SKANIDA Insurance Company and Atlas Copco. *Department tDepartment
of Medicine, Karolinska Institutet, Serafimerlasarettet, Stockholm, Sweden. of Social Medicine, Karolinska Institutet, Huddinges jukhus, Huddinge, Sweden. 219
S. AHNVE, U. DE FAIRE, K. ORTH-GO&R and T. THE~RELL
220
All subjects in this study were men, 40-65 years old, and still actively employed at the time of examination. The mean age was 54.5 (range 40-65) for the observation group, 58.9 (range 49-65) for the infarction group, 56.8 (range 41-65) for the control group. Figure 1 illustrates the professional status of the subjects. They were divided into four categories: (1) upper, (2) ‘lower white collars’, (3) upper and (4) lower ‘bluecollars’. White collars and blue collars were distributed in approximately the same way in all three groups. Slightly more than 2/3 of the subjects were white collars: 24/34, 16/23 and 30/43 respectively.
lnfaktion
group
q OS% jroup 0
Control
group
20
Upper white collar FIG. I.-Distribution
Lower white collar
Upper blue collar
of professional
Lower blue collar
Level of profeslion
status in the three groups studied.
METHODS All subjects were asked to fill out a questionnaire comprising questions about everyday behaviour and background factors. Furthermore, a self-administered ‘Adjective Check List’ (ACL) was used for evaluation of ‘Type-A behaviour’ according to Rahe and Rosenman [6]. This instrument was derived from an experiment performed by Rosenman et nl. [7] in which a number of questionnaires were studied with regard to their ability to correlate with Type-A behaviour assessments according to the original interview ratings described by Rosenman et al. [l]. Angina pectoris was defined in accordance with WHO criteria [8]. The requirement for acceptance of a patient’s report of previous myocardial infarction was that the diagnosis could be verified from a hospital record or ECG. The follow-up examination included a comprehensive case history, physical examination, blood pressure measurement, ECGs, maximal exercise test with a continuously increasing load [9] and an X-ray of heart and lungs. The significance of differences in the distributions of responses to the every-day behaviour questionnaire was tested by means of two-tailed Chi-square tests. The significance of differences in means of Type-A score (ACL), was hypothesized to be zero (two-tailed t-tests).
RESULTS Adjective
check-list
All scores from ACL are plotted in Fig. 2. One subject in both the OBS-group and the infarction group was excluded because of missing data.
Type-A behaviour in patients with non-coronary
l
xx 2X
chest pain
221
*Born 1911-1915 xBorn 1916and later.
z. X X
xx&x
“:F i% xxex “Z a
X
3 l
I Infarction (rl=33)
FIG. 2.-Scores
“OBS” In=221
Control (n=43)
of ‘Adjective check list’ in three groups studied.
The mean score of the OBS-group (30.1 f 4.6) was significantly elevated as compared both with the infarction grouu (26.9 + 4.3. D < 0.02). and the control aroun (25.7 f 5.1. a < 0.001). However. the exclusion of subjects b&n earher than i916 increased the-level of significance (p < 0.005) between the OBS-group (mean score 30.2 k 4.7) and the infarction group (mean score 25.5 + 3.8). The level of significance was decreased (p < 0.02) between the OBS-group and control group (mean score 26.9 f 3.6). No difference was obtained between the infarction and control group irrespective of age limit.
Background
factors
and everyday
behaviour
Most subjects in all groups had lived with both biological parents until age 15 [Table 1 (a)]. No difference was obtained between the three groups regarding satisfaction with home life [Table 1 (b)], and energy level in comparison with friends of the same age [Table 1 (c)l. The subjects in the OBSgroup more often complained of too much responsibility at work [Table 1 (d)] and also said they were less satisfied at work [Table 1 (e)], especially when compared to subjects in the control group. Men in the OBS-group cla!med that it was usually hard for them to relax after a normal working day frable 1 (f)]. Another feature of high prevalence in the OBS-group was a feeling of impatience in queues [Table 1 (g)] and impatience with slow persons [Table 1 (h)]. A high reported rate of impatience with slow persons was demonstrated also among subjects in the control group.
222
S. AHNVE,U. DE FAIRE, K. ORTH-GOI&R and T. THEORELL
TABLE l.-BACKGROUND FACTORS AND EVERYDAY BEHAVIOUR IN THE INFARCTION GROUP (n = 34), OBSERVATION GROUP(n = 23)AND CONTROLGROUP(n = 43) (a) Lived with both biological parentsuntilage fifteen Yes Infarctiongroup
OBS-group Control group
25 15 36
No
9 8 7
* -= 0.45 N.S. .l’ = 2.92 N.S. f = 1.20 N.S.
(b) Satisfaction with home life Very good More than very good _ 23 11 ‘* =: 1.39 N.S. 12 11 ‘i == 2.00 N.S. 30 13 :: = 0.04 N.S. _._(c) Energy level in comparison with friends of the same age Average or less More -~ Infarction group 12 22 * =: 0.90 N.S. OBS-group 11 12 i_ = 0.01 N.S. Control group 20 23 : = 0.98 N.S. ~~(d) Responsibility at work Too much or too little Just right Infarction group 18 15 I * = 2.82 N.S. OBS-group 7 14 2 i = 8.28p < 0.01 Control group 13 1 29 $ = 1.68 N.S. (e) Satisfaction at work Indifferent or not good Good or very good Infarction group 27 7 * = 1.43 N.S. OBS-group 15 8 .i- = 8.43 p < 0.01 Control group : = 3.11 N.S. 40 3 ~~._-.______ (f) Ability to relax after normal working day Sometimes or more infrequently Mostly or always -_-__ ~~8 * = 6.42~ < 0.05 Infarction group 26 13 I- = 13.25~ < 0.001 OBS-group 10 6 # = 1.17 N.S. Control group 37 (g) Impatience in queues At least somewhat None at all 23 * = 2.76 N.S. Infarction group 11 20 t = 8.3Op < 0.01 OBS-group 3 22 $ = 2.12 N.S. Control group 21 (h) Impatience with slow persons At least somewhat None at all 21 -* = 4.31 p < 0.05 Infarction group 13 20 t = 0.03 N.S. OBS-group 3 38 ?L= 7.50 1, < 0.01 Control groun 5 Infarction group OBS-group Control group
Chi-square analyses between : * = OBS-group and Infarction group. T = OBS-group and Control group. $ = Infarction group and Control group. During the follow-up period 48 % in the OBS-group had had symptoms of gastritis (13 % recurrent symptoms of peptic ulcer), 26 ‘A symptoms of cervical spondylosis and 22 ‘A were at the examination heavy smokers with symptoms of chronic bronchitis. Corresponding data were not available for the other groups. DISCUSSION
The present findings demonstrate that the observation cases exhibited more Type-A behaviour, as judged from the ACL test, than the infarction and control cases. This is perhaps somewhat unexpected. Rosenman et al. [l] consider Type-A behaviour to be linked with an enhanced risk of coronary heart disease. The difference demonstrated
Type-A behaviour in patients with non-coronary
chest pain
223
in the present study could not be explained on the basis of biased drop out, sex or occupational differences. There were unequal distributions in the three groups with regard to age. This, however, could not explain the differences in Type-A score between the OBS-group and the other groups. The exclusion of the oldest age category, did change the significance of differences in Type-A scores, but still there were significant differences between the OBS-group and the other groups. Patients of the infarction group had suffered their AMI 2-4 years prior to the study, a fact that could have had a ‘dilution’ effect on a typical Type-A behaviour possibly present prior to the AM1 [lo]. This may explain why the infarction patients did not deviate from the control cases with regard to Type-A behaviour. The differences obtained regarding Type-A behaviour were also confirmed by the responses to the questionnaire about background factors and everyday behaviour administered to the groups studied. The observation group reported more dissatisfaction with work, more impatience and less ability to relax. No data for comparison were available, but it seems to us that an unexpectedly large proportion of the observation cases frequently suffered from acute or chronic gastritis. Impatience with slow persons and in queues have previously been associated with risk of developing longlasting gastritis [3]. The findings in the present study may partially reflect this. Psychic ‘stress’ at onset of symptoms and feeling of palpitations are commonly reported by non-infarction patients admitted to CCU’s [5, 111. From these data it could be questioned whether Type-A behaviour is as specific for the coronary prone person as earlier claimed [l]. Type-A behaviour may even be more linked with the development of other diseases such as acute or chronic gastritis. It can be assumed that a lot of persons who get chest pains, without having ischaemic heart disease, are afraid of getting an acute myocardial infarction. Such persons seeking aid having Type-A measure may have special features making them prone being admitted to CCU. Acknowledgement-This study was supported against Heart and Chest Diseases.
by grants from the Swedish National
Association
REFERENCES 1. ROSENMANR. H., BRAND R. J., JENKINSC. D., FREIDMANM., STRAWSR. and WURM M. Coronary heart disease in the western collaborative group study. Final follow-up experience of 8$ years. J. Am. Med. Ass. 233, 872 (1975). 2. ORTH-GOM~~RK. Ischaemic heart disease as a result of psychosocial process. Sot. Sci. Med. 8 (1974). 3. THEORELLT., L,~NDE. and FLODERUSB. The relationship of disturbing life-changes and emotions to the early development of myocardial infarctions and other serious illnesses. Znr. J. Epidem. 4, 281 (1975). 4. THEORELLT., ERHARDTL. R., LIND E., SJ&REN A. and S;~WEU. Selected psychosocial variables in the delay of reaching the coronary care unit. Acta Med. &and. 198,315 (1975). 5. AHNV~ S. Non-infarction patients without previously known ischaemic heart disease admitted to a coronary care unit. Eur. J. Cardiol, 307 (1979). 6. RAHE R. H., HERVIGL. B. and ROSENMANR. H. The heritability of Type-A behaviour. Psychosom. Med. 6, 478 (1978). 7. ROSENMANR. H., RAHE R. H., BORHANIN. 0. and FEINLIEBM. Heritability of personality and behaviour pattern. U.S. Navy (1975). 8. ROSE G. and BLACKBURNH. Cardiovascular Survey Methods. World Health Organization, Geneva (I 968). 9. .&TR~M H. and JONSSONB. Design of exercise test with special references to heart patients. Br. Heart J. 38, 289 (1976). 10. JENKINSC. D., ZYZANSKI S. J., ROSENMANR. H. and CLEVELAUDG. L. Association of coronaryprone behaviour scores with recurrence of coronary heart disease. J. Chron. Dis. 24,601 (1971). 11. Sjiw~ U. Early diagnosis of acute myocardial infarction. Acfa Med. S-and. Suppl. 545 (1972).
TYPE-A BEHAVIOUR IN PATIENTS WITH NON-CORONARY CHEST PAIN ADMITTED TO A CORONARY CARE UNIT S. AHNVE,*
U. DE FAIRE,* K. ORTH-GOM~R*
and T.
THEORELL*
(Received 20 February 1979) Abstract-The present study is focused on the behaviour of 23 men admitted to a coronary care unit for suspected acute myocardial infarction and turned out not to suffer from ischaemic heart disease even at a follow-up 2-4 years later (OBS-group). These patients are compared with 34 infarction patients and 43 healthy control subjects. For evaluation of Type-A behaviour a self administered ‘Adjective check-list’ was used. The mean score from that list was significantly elevated in the OBSgroup as compared both with the infarction group (p < 0.02) and the control group (p < 0.001). No difference was obtained between the two latter groups. It is concluded that Type-A behaviour may be a common feature among persons with non-coronary chest pain, admitted to a coronary care unit.
TYPE-A
BEHAVIOUR
is characterized
by ambitious,
obsessive
and
impatient
striving
and has been associated with elevated risk of developing ischaemic heart disease (IHD) in middle-aged men [l]. It is questionable, however, whether this type of
behaviour is specific for the coronary prone person [2]. Some investigations have tried to identify behaviour characteristics specific for other disorders. For instance, longlasting gastritis and duodenal ulcer have been associated with irritability, also as a feature of pattern A behaviour, in a prospective study of middle-age men [3]. A study previously published from this hospital indicated that ‘inability to relax during leisure’ was associated with a relatively short delay from onset of chest pain to admittance to a coronary care unit (CCU), [4]. The aim of the present study was to investigate the behaviour of patients who are admitted to a CCU for suspected acute myocardial infarction (AMI) due to central chest pain, and turned out not to suffer from IHD even at a follow-up 2-4 years later [5]. These subjects have been compared with patients who did suffer from myocardial infarction and with healthy control subjects.
MATERIAL During the period 1 June 1972 to 15 May 1974, 59 men without a previous history of IHD (i.e. angina pectoris or myocardial infarction) were admitted to the CCU because of central chest pain, and turned out not to have AM1 [5]. By the time of the follow-up 2-4 years later there were 47 men still alive and willing to participate. Twenty-three of these 47 were I 65 years of age at that time and they constituted the observation group (OBS-group). The infarction group consisted of 34 men i 65 years of age with a history of AM1 2-4 years earlier. They were selected from the out-patient clinic during the follow-up period in 1976. Forty-three healthy men were also examined and used as controls (control group). They were randomly chosen from the payroll of three large enterprises in the Stockholm area: LM Ericson, SKANIDA Insurance Company and Atlas Copco. *Department tDepartment
of Medicine, Karolinska Institutet, Serafimerlasarettet, Stockholm, Sweden. of Social Medicine, Karolinska Institutet, Huddinges jukhus, Huddinge, Sweden. 219
S. AHNVE, U. DE FAIRE, K. ORTH-GO&R and T. THE~RELL
220
All subjects in this study were men, 40-65 years old, and still actively employed at the time of examination. The mean age was 54.5 (range 40-65) for the observation group, 58.9 (range 49-65) for the infarction group, 56.8 (range 41-65) for the control group. Figure 1 illustrates the professional status of the subjects. They were divided into four categories: (1) upper, (2) ‘lower white collars’, (3) upper and (4) lower ‘bluecollars’. White collars and blue collars were distributed in approximately the same way in all three groups. Slightly more than 2/3 of the subjects were white collars: 24/34, 16/23 and 30/43 respectively.
lnfaktion
group
q OS% jroup 0
Control
group
20
Upper white collar FIG. I.-Distribution
Lower white collar
Upper blue collar
of professional
Lower blue collar
Level of profeslion
status in the three groups studied.
METHODS All subjects were asked to fill out a questionnaire comprising questions about everyday behaviour and background factors. Furthermore, a self-administered ‘Adjective Check List’ (ACL) was used for evaluation of ‘Type-A behaviour’ according to Rahe and Rosenman [6]. This instrument was derived from an experiment performed by Rosenman et nl. [7] in which a number of questionnaires were studied with regard to their ability to correlate with Type-A behaviour assessments according to the original interview ratings described by Rosenman et al. [l]. Angina pectoris was defined in accordance with WHO criteria [8]. The requirement for acceptance of a patient’s report of previous myocardial infarction was that the diagnosis could be verified from a hospital record or ECG. The follow-up examination included a comprehensive case history, physical examination, blood pressure measurement, ECGs, maximal exercise test with a continuously increasing load [9] and an X-ray of heart and lungs. The significance of differences in the distributions of responses to the every-day behaviour questionnaire was tested by means of two-tailed Chi-square tests. The significance of differences in means of Type-A score (ACL), was hypothesized to be zero (two-tailed t-tests).
RESULTS Adjective
check-list
All scores from ACL are plotted in Fig. 2. One subject in both the OBS-group and the infarction group was excluded because of missing data.
Type-A behaviour in patients with non-coronary
l
xx 2X
chest pain
221
*Born 1911-1915 xBorn 1916and later.
z. X X
xx&x
“:F i% xxex “Z a
X
3 l
I Infarction (rl=33)
FIG. 2.-Scores
“OBS” In=221
Control (n=43)
of ‘Adjective check list’ in three groups studied.
The mean score of the OBS-group (30.1 f 4.6) was significantly elevated as compared both with the infarction grouu (26.9 + 4.3. D < 0.02). and the control aroun (25.7 f 5.1. a < 0.001). However. the exclusion of subjects b&n earher than i916 increased the-level of significance (p < 0.005) between the OBS-group (mean score 30.2 k 4.7) and the infarction group (mean score 25.5 + 3.8). The level of significance was decreased (p < 0.02) between the OBS-group and control group (mean score 26.9 f 3.6). No difference was obtained between the infarction and control group irrespective of age limit.
Background
factors
and everyday
behaviour
Most subjects in all groups had lived with both biological parents until age 15 [Table 1 (a)]. No difference was obtained between the three groups regarding satisfaction with home life [Table 1 (b)], and energy level in comparison with friends of the same age [Table 1 (c)l. The subjects in the OBSgroup more often complained of too much responsibility at work [Table 1 (d)] and also said they were less satisfied at work [Table 1 (e)], especially when compared to subjects in the control group. Men in the OBS-group cla!med that it was usually hard for them to relax after a normal working day frable 1 (f)]. Another feature of high prevalence in the OBS-group was a feeling of impatience in queues [Table 1 (g)] and impatience with slow persons [Table 1 (h)]. A high reported rate of impatience with slow persons was demonstrated also among subjects in the control group.
222
S. AHNVE,U. DE FAIRE, K. ORTH-GOI&R and T. THEORELL
TABLE l.-BACKGROUND FACTORS AND EVERYDAY BEHAVIOUR IN THE INFARCTION GROUP (n = 34), OBSERVATION GROUP(n = 23)AND CONTROLGROUP(n = 43) (a) Lived with both biological parentsuntilage fifteen Yes Infarctiongroup
OBS-group Control group
25 15 36
No
9 8 7
* -= 0.45 N.S. .l’ = 2.92 N.S. f = 1.20 N.S.
(b) Satisfaction with home life Very good More than very good _ 23 11 ‘* =: 1.39 N.S. 12 11 ‘i == 2.00 N.S. 30 13 :: = 0.04 N.S. _._(c) Energy level in comparison with friends of the same age Average or less More -~ Infarction group 12 22 * =: 0.90 N.S. OBS-group 11 12 i_ = 0.01 N.S. Control group 20 23 : = 0.98 N.S. ~~(d) Responsibility at work Too much or too little Just right Infarction group 18 15 I * = 2.82 N.S. OBS-group 7 14 2 i = 8.28p < 0.01 Control group 13 1 29 $ = 1.68 N.S. (e) Satisfaction at work Indifferent or not good Good or very good Infarction group 27 7 * = 1.43 N.S. OBS-group 15 8 .i- = 8.43 p < 0.01 Control group : = 3.11 N.S. 40 3 ~~._-.______ (f) Ability to relax after normal working day Sometimes or more infrequently Mostly or always -_-__ ~~8 * = 6.42~ < 0.05 Infarction group 26 13 I- = 13.25~ < 0.001 OBS-group 10 6 # = 1.17 N.S. Control group 37 (g) Impatience in queues At least somewhat None at all 23 * = 2.76 N.S. Infarction group 11 20 t = 8.3Op < 0.01 OBS-group 3 22 $ = 2.12 N.S. Control group 21 (h) Impatience with slow persons At least somewhat None at all 21 -* = 4.31 p < 0.05 Infarction group 13 20 t = 0.03 N.S. OBS-group 3 38 ?L= 7.50 1, < 0.01 Control groun 5 Infarction group OBS-group Control group
Chi-square analyses between : * = OBS-group and Infarction group. T = OBS-group and Control group. $ = Infarction group and Control group. During the follow-up period 48 % in the OBS-group had had symptoms of gastritis (13 % recurrent symptoms of peptic ulcer), 26 ‘A symptoms of cervical spondylosis and 22 ‘A were at the examination heavy smokers with symptoms of chronic bronchitis. Corresponding data were not available for the other groups. DISCUSSION
The present findings demonstrate that the observation cases exhibited more Type-A behaviour, as judged from the ACL test, than the infarction and control cases. This is perhaps somewhat unexpected. Rosenman et al. [l] consider Type-A behaviour to be linked with an enhanced risk of coronary heart disease. The difference demonstrated
Type-A behaviour in patients with non-coronary
chest pain
223
in the present study could not be explained on the basis of biased drop out, sex or occupational differences. There were unequal distributions in the three groups with regard to age. This, however, could not explain the differences in Type-A score between the OBS-group and the other groups. The exclusion of the oldest age category, did change the significance of differences in Type-A scores, but still there were significant differences between the OBS-group and the other groups. Patients of the infarction group had suffered their AMI 2-4 years prior to the study, a fact that could have had a ‘dilution’ effect on a typical Type-A behaviour possibly present prior to the AM1 [lo]. This may explain why the infarction patients did not deviate from the control cases with regard to Type-A behaviour. The differences obtained regarding Type-A behaviour were also confirmed by the responses to the questionnaire about background factors and everyday behaviour administered to the groups studied. The observation group reported more dissatisfaction with work, more impatience and less ability to relax. No data for comparison were available, but it seems to us that an unexpectedly large proportion of the observation cases frequently suffered from acute or chronic gastritis. Impatience with slow persons and in queues have previously been associated with risk of developing longlasting gastritis [3]. The findings in the present study may partially reflect this. Psychic ‘stress’ at onset of symptoms and feeling of palpitations are commonly reported by non-infarction patients admitted to CCU’s [5, 111. From these data it could be questioned whether Type-A behaviour is as specific for the coronary prone person as earlier claimed [l]. Type-A behaviour may even be more linked with the development of other diseases such as acute or chronic gastritis. It can be assumed that a lot of persons who get chest pains, without having ischaemic heart disease, are afraid of getting an acute myocardial infarction. Such persons seeking aid having Type-A measure may have special features making them prone being admitted to CCU. Acknowledgement-This study was supported against Heart and Chest Diseases.
by grants from the Swedish National
Association
REFERENCES 1. ROSENMANR. H., BRAND R. J., JENKINSC. D., FREIDMANM., STRAWSR. and WURM M. Coronary heart disease in the western collaborative group study. Final follow-up experience of 8$ years. J. Am. Med. Ass. 233, 872 (1975). 2. ORTH-GOM~~RK. Ischaemic heart disease as a result of psychosocial process. Sot. Sci. Med. 8 (1974). 3. THEORELLT., L,~NDE. and FLODERUSB. The relationship of disturbing life-changes and emotions to the early development of myocardial infarctions and other serious illnesses. Znr. J. Epidem. 4, 281 (1975). 4. THEORELLT., ERHARDTL. R., LIND E., SJ&REN A. and S;~WEU. Selected psychosocial variables in the delay of reaching the coronary care unit. Acta Med. &and. 198,315 (1975). 5. AHNV~ S. Non-infarction patients without previously known ischaemic heart disease admitted to a coronary care unit. Eur. J. Cardiol, 307 (1979). 6. RAHE R. H., HERVIGL. B. and ROSENMANR. H. The heritability of Type-A behaviour. Psychosom. Med. 6, 478 (1978). 7. ROSENMANR. H., RAHE R. H., BORHANIN. 0. and FEINLIEBM. Heritability of personality and behaviour pattern. U.S. Navy (1975). 8. ROSE G. and BLACKBURNH. Cardiovascular Survey Methods. World Health Organization, Geneva (I 968). 9. .&TR~M H. and JONSSONB. Design of exercise test with special references to heart patients. Br. Heart J. 38, 289 (1976). 10. JENKINSC. D., ZYZANSKI S. J., ROSENMANR. H. and CLEVELAUDG. L. Association of coronaryprone behaviour scores with recurrence of coronary heart disease. J. Chron. Dis. 24,601 (1971). 11. Sjiw~ U. Early diagnosis of acute myocardial infarction. Acfa Med. S-and. Suppl. 545 (1972).
