Australian and New Zealand Journal of Psychiatry

(1976) 10: 27

A SCALE TO MEASURE THE STRESS OF LIFE EVENTS* by CHRISTOPHER TENNANT** and GAWN ANDREW$***

SYNOPSI6 A mmprehensive life event inventory suitable for questionnaire or interviewer administration has been construl&ed. Two sets of matched scalings of these life events

have been derived from the responses of can Amtrdian urban papulation. Each of the scalings were ansiatent across the socioslemographic groups in the population. The two wales dlow the signiikance of life even@ to be scaled in conceptually different ways. The first follows Holmes concept of the extent of life change m u r e d by the event, the second the Paykel concept of the ammd of dhtress caused by the event. The inventory and the scalings are suitable for use in an Ausbrdhn urban population. The onset of both physical and psychological illness has been shown to be preceded by an increased frequency of life events. This relationship holds for illness in general and for specific illnesses as diverse as myocardial infarction (Theorell and Rahe, 197 1); multiple sclerosis (Antonovsky and Kats, 19’67); and schizophrenia (Birley and Brown, 1970). This relationship is usually regarded as causal, the mechanism postulated for physical illness being physiological arousal, increased adrenal activity and immunosuppression. *Presented at the First Pacific Congress of Psychiatry; Melbourne, May 1975. **Research Fellow, New South Wales Institute of Psychiatry. ***Associate Professor of Psychiatry, University of New South Wales.

The stress of life events has been assessed in a number of ways. The most simple method is to count the number of specified events, be they major or minor, experienced by an individual in a given period of time. This method does not take into account the fact that certain events may be more significant psychologically or more stressful physiologically than others. With this in mind several authors have constructed life event inventories in which each event is scaled for its significance in relation to the other events. Such scaled life event inventories are presumed to be a better measure of environmental stress. They have been used to examine the relationship between the cumulative stress produced by the occurrence of life events and the subsequent onset of illness. Such weighted life event inventories or scales have usually been constructed in accord with two different principles. Following Selye’s ( 1956) pioneering work, Holmes and Rahe (1967) proposed that it was the magnitude of the change produced by the event which was associated with the later onset of illness. Their “Social Readjustment Rating Scale’’ was therefore constructed by having 394 adults score 43 events for significance in terms of the amount of “change in one’s usual way of life” caused by each event, irrespective of the desirable or undesirable quality of the event. Using this scale, the event experience of individuals in various illness groups was then assessed, each event experienced by that individual being allocated the appropriate score as derived from the Social Readjustment Rating Scale. The cumulative life change score for each individual was calculated as the sum of the scalings for the events experienced. High Scores for life change were shown to be associated with the later occurrence of illness.

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A SCALEM MEASURE STRESS

In contrast, Paykel, Prusoff and Ulenhuth (1971) proposed that it was specifically the undesirable or distressing quality of events which was associated with subsequent onset of illness. In constructing their inventory, 373 adults scaled 61 events for their significance in terms of the distress and upset likely to be caused by the experience of such events. In studies of depression and schizophrenia Paykel et al. (1969) and Birley and Brown (1970) respectively, have shown that the onset of these psychiatric illnesses are both preceded by a significant increase in distressing life events. Comparing the distress scale (Paykel et al., 1971) with the life change scale (Holmes and Rahe, 1967), Paykel found a rank order correlation co-efficient of 0.68 for the 14 items which were common to both scales. This suggests that there is some association between the magnitude of life change that follows a given event and the degree of emotional distress it causes. For example, an event such as divorce causes both a marked change in life style and much emotional distress. Other events, however, may not demonstrate this strong association between the degree of change and amount of emotional distress. Marriage may cause a marked change in life style and yet should not cause emotional distress. Thus these two methods of scaling life events appear to be conceptually distinct. The present study describes the construction of a 67 item life event inventory and the subsequent scaling of these events in terms of their capacity to produce either a “change in life style” or “emotional distress”. These two scales were constructed for use in Australia since the original scales of Holmes and Rahe (1967) and Paykel et al. (1971) were Calibrated on heterogenous American populations and may not be applicable to Australian populations.

METHODOLOGY Sixty-seven life event items were derived from the 61 items used by Paykel et al. ( 1971) and the 43 items of Holmes and Rahe (1967). The items were selected so that the widest possible range of human experience could be included in an inventory of manageable size. Relatively uncommon events were only included if they were obviously major stressors and relatively minor events were included only if likely to occur relatively frequently. As a result of pilot testing, the original wording of many items was changed to aid understanding in the Australian setting. The complete list of items is displayed in Table 1.

is essential that the scalings of each individual item be related proportionately to the other items. Thus a ratio method of scaling, as described by Stevens and Galanter (1957) and Holmes and Rahe (1967) was used in the derivation of this life events scale. One requirement of this ratio method of scaling is that all events are scaled by comparing each of them individually with an index item. Holmes and Rahe, for example, chose “marriage” as their index item. A score was then allocated to each item in proportion to its significance when compared with that index item and the mean score for each item then calculated. Since one objective of the present study was to construct two comparable scales, one for life change and one for distress, it was necessary that the same index item be used in each scaling procedure. If possible, the index item should be equally significant on each scale, so that the scales may indeed be truly comparable. Thus it was necessary initially to prescale the 67 items for both life change and emotional distress, in order to find an item which was of equal significance on each scale. This item could then be used as an index item for the final scaling procedure. For the prescaling procedure, a sample of 94 adult individuals was selected consisting of 31 hospital staff and 63 local community members. They were asked on two separate occasions to score the 67 items using a 0-20 scale of importance (after Paykel et al., 1971). On one occasion, events were scaled for the degree of life change required and on the other occasion, they were scaled for degree of emotional distress involved. Mean scores were calculated for each event for both life change and distress. The rank orders of each event on both the life change and distress scales were derived and compared. The two scales were examined and the item “a serious personal physical illness’’ was selected for use as an index item for the final and definitive scaling. This item was selected since its scores for degree of significance on the life change and distress scales were 13.6 and 13.9 respectively, and the item ranked 17th and 20th respectively in the two scales. The rank order of this item on the present “life change” scale was 8th compared with its rank order of 6th on Holmes’ scale (using only the 22 comparable events). The rank order of this same item on the present “distress” scale when compared with the rank order on Paykel’s scale (using the 59 comparable events) was 18th in both instances.

In order to demonstrate a relationship between

These results indicate that the item “A serious personal physical illness” is of apparently equal significance in terms of both the life change and emotional distress it may cause and was therefore a suitable index item for use in the final scaling procedure.

cumulative life stress and subsequent illness, it is necessary to calculate the cumulative scaled life events score for each individual. For this cumulative score to be calculated with any degree of validity, it

The final scaling was carried out using the above item as an index item. A sample of 151 adults scored the other 66 items using a modified ratio scaling method. This sample comprised 78 males and 73

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CHRISTOPHER

TENNANT AND GAVINANDREWS

females whose age ranged from 20 to 69 with a mean f the sample, 42 were single and age of 35 years. O 109 married, while 58 were medical personnel and 93 were nonmedical members of the local community. The sample was weighted towards the upper socioeconomic groups since 111 were from professional, managerial or administrative occupations while only 40 persons were employed in clerical, skilled or unskilled occupations. The scaling method involved the use of 67 printed cards each of which contained a single life event. The cards were presented to the subject singly in a random order. Each event in turn was compared with the index event and allocated an appropriate ratio score. The mean value for each item, for each of the two concepts, was calculated for the whole sample. In this way, two matched scales were obtained, one a life change scale, the other an emotional distress scale.

RESULTS The arithmetic mean scores for the items as scaled for both emotional distress and life change are shown in Table 1. The consistency with which the various sociodemographic subgroups scored the 67 items on both scales were assessed using Spearman rank order correlations. For the distress scale the rank order correlations between the scalings of males and females, between upper and lower occupational statuses, and between medical personnel and nonmedical personnel were all 0.98. The correlations between the scalings of the marrieds and the singles and between those younger than 40 years and those 40 or older were both 0.97. The rank order correlations between the life change scalings for the same subgroups were slightly lower and ranged from 0.93 to 0.97. These results demonstrate that there is a high consistency in the way various sociodemographic groups in the community rated the relative significance of these 67 life events. The subgroups were more consistent when rating events for distress than when rating events for life change. Spearman rank order correlations were also calculated between the 59 comparable events on the present distress scale and those published by Paykel and between the 22 comparable events on this life change scale and those published by Holmes. The correlations were 0.92 and 0.87 respectively, indicating a surprising level of consistency between the present sets of scalings and similar scales constructed b y the two authors. When the two present scales were examined and the two separate scores for each item compared. it can be seen that a number of events score high for both “life change” and “emotional distress” whilst other events show markedly different scores on the separate scales. The overall rank order correlation between these two scales was relatively low (r = 0.44). This supports the hypothesis that the two concepts of

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“life change” and “emotional distress” were seen by the scaling population to be relatively distinct, i.e. that the “life change” caused by an event, is relatively independent of the “emotional distress” it may cause.

DIsiCUSSION Items chosen for use in this life events inventory were selected so that a wide range of life events experience was included. Both desirable and undesirable events were selected so that the relationship between the quality of life event experience and subsequent onset of illness could later be examined. TO avoid ambiguous interpretation by either respondents involved in the scaling procedure or individuals completing the inventory, each item was defined as specifically as possible. Items which might reflect obvious symptoms of illness such as “change in eating habits” and which have been included in other life event inventories, were deleted to avoid possible contamination between events and illness. Sixty-seven items, a manageable number, were thus obtained.

In the prescaling procedure an interval method of scaling was used so that one item of equal significance and rank order on both life change and distress scales could be selected for use as an index item for the final scaling procedure. In the final procedure however, a ratio method of scaling was used so that scalings obtained for each item related in a proportionate way to all other items on the scale. This permitted the summation of individual scores to produce a cumulative distress or life change score. Since individuals in different cultures may not perceive the significance of life events in the same way (Miller, Benz, Aponte, and Brogan, 1974) it is necessary when examining the relationships of cumulative life stress and illness onset in one population, to use scalings which have been derived from a similar population. The scaling population selected to generate this set of scalings for use in Australia was somewhat weighted toward the upper socioeconomic groups since individuals in low socioeconomic groups had difficulty in complying with the scaling procedure. Nonetheless, in the present material there was high consistency between the mean scalings of the upper and lower status groups indicating a judgement of adversity that may be common to all urban Australians. Despite the original work of Selye (1956) who postulated that any life change caused physiological arousal and increased susceptibility to illness there has been controversy as to whether it is life change in general or distressing events in particular which are causally associated with illness onset. Indeed one illness may be associated more strongly with events of one quality, whilst another illness is associated more strongly with the other quality. The present life events inventory, with its two matched scalings for life change and distress, will permit examination of this controversial issue in various patient groups.

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A SCALETO MEASURESTRESS

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TABLE 1 Life Events Inventory (Questionnaire Form) EVENT HEALTH

5. 6. 7. 8. 9. 10.

LIFE CHANGE SCALINGS

( M e n and Women)

1. You had a minor illness or injury like one needing a visit to a doctor or a couple of days off work 2. You had a serious illness, injury or operation needing hospitalization or a month or more off work 3. A close relative had a serious illness (from which they did not die) 4.

DISTRESS SCALINGS

(Women Only) You are pregnant (with a wanted pregnancy) You are pregnant (with an unwanted pregnancy) You had a stillbirth You had an abortion or miscarriage You had a baby Your change of life (menopause) began You adopted a child

2

2

16

16

16

9

2 33 40 26

(Men Only) 11. Your wife had a child or you adopted a child

BEREAVEMENT ( M e n and W o m e n ) 12. Your wifelhusband died 13. A child of yours died 14. A close family member died (e.g. parent, brother, etc) 15. A close family friend or relative died (e.g. Aunt, Uncle, Grandmother, Cousin, etc) FAMILY AND SOCIAL (If you are or were married) 16. You married 17. There has been increasing serious arguments with your wife/ husband 18. There has been a marked improvement in the way you and your wife/husband are getting on 19. You have been separated from your husband/wife for more than a month because of marital difficulties 20. You have been separated from your wife/husband for more than a month (for reasons other than marital difficulties) 21. You have got back together again after a separation due to marital difficulties 22. You began an extramarital affair 23. Your wife/husband began an extramarital affair 24. You have been divorced

(Zj y o u have or had children) 25. A child of yours became engaged 26. A child of yours married with your approval 27. A child of yours married without your approval 28. A child of yours left home for reasons other than marriage 29. A child of yours entered the armed services

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14 4

26 29 22 13 41 18 47

4

41

83 80 57

'79 57 21

30

I2

5

59

26

25

5

2 31

29

12

I5

5 14 35 54

25 28 28 62

2 2 22

6

11

9

10 16 14 10

31

CHRISTOPHER TENNANT AND G A V ~ANDREWS N

EVENT

30. 31. 32. 33.

DISTRESS SCALINGS

LIFE CHANGE SCALINGS

2 25 18

17 21 18

15

13

8

20

I

10

13

13

16

16

10

8

3 5 2 14 10 20

16 11 27 22 13 18

20 38 32 15 20 2

22 44 34 53 18 18

10

9 16

( I f you are single) You became engaged or began a “steady” relationship You broke off your engagement You broke off a “steady” relationship You had increasing arguments or difficulties with your fiance or steady friend

FRIENDS AND RELATIVES 34. A new person came to live in your household (apart from a new baby) 35. There has been a marked improvement in the way you get on with someone close to you (excluding husband and wife) 36. You have been separated from someone important t o you (other than close family members) 37. There has been serious increase in arguments or problems with someone who lives at home (excluding husband or wife) 38. There has been serious problems with a close friend, neighbour or relative not living at home

EDUCATION 39. You started a course (i.e. University. Tech. College, Business College, apprenticeship or other occupational training course) 40. You change to a different course 41. You completed your training program 42. You dropped out of your training program 43. You studied for, or did, important exams 44. You failed an important exam

WORK 45. You have been unemployed and seeking work for a month or more 46. Your own business failed 47. You were sacked 48. You retired 49. You were downgraded or demoted at work 50. You were promoted 51. You began to have trouble or disagreements with your boss, supervisor or fellow workers 52. You had a big change in the hours you worked 53. You had a big change in the people, duties or responsibilities in your work 54. You started in a completely different type of job 55. You had holidays for a week or more

5

17

7 8 1

24

19 8 4

48 26 11

5

MOVING HOUSE 56. You moved to Sydney from overseas 57. You moved to Sydney from elsewhere in Australia 58. You moved house in Sydney

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A SCALETO MEASURE STRESS

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SC ALINGS

LIFE CHANGE SCALINGS

9 34 1

10 37 23

31

22

4

2

21 59

15 72

25 9

21 5

DISTRESS

EVENT FINANCIAL AND LEGAL 59. 60. 61. 62. 63. 64. 65. 66.

67.

You had moderate financial difficulties You had a major financial crisis You are much better off financially You were involved in a traffic accident that carried serious risk to the health or life of yourself or others You had minor difficulties with the police or the authorities [which has not required a court appearance (e.g. speeding fine, etc)l You had more important problems with the police or the authorities (leading to a court appearance) You had a jail sentence or were in prison You were involved in a civil law suit (eg. divorce, debt, custody, etc) Something you valued or cared for greatly was stolen or lost

REFERENCES Antonovsky, A. and Kats, Rachel (1967). The life crisis history as a tool in epidemiological research. Journal of Health and Social Behaviour, 8: 15. Birley, J. L. T. and Brown, G. W. (1970). Crises and life changes preceding the onset or relapse of acute schizophrenia: clinical aspects. British Journal of Psychiatry, 116: 327. Holmes, T. H. and Rahe, R. H. (1967). The social readjustment rating scale. Journal o f Psychosomatic Research, 11: 213. Miller, F. T., Bentz, W. K.. Aponte, J. F. and Brogan, D. R. (1974). Perception of life crisis events; a comparative study of rural and urban samples, in Stressful Life Events: Their Nature and E#ects. (eds. Dohrenwend, Barbara and Dohrenwend, B. P.), Wiley and Sons, New York.

Paykel, E. S., Myers, J. K., Dienelt. M. N., Klerman, G. L., Lindenthal. J. J. and Pepper, M. P. (1969). Life events and depression. Archives of General Psychiatry, 21: 753. Paykel, E. S., Prusoff, Brigitte, A. and Uhlenhuth, E. H. (1971). Scaling of life events. Archives of General Psychiatry, 25: 340. Selye, H. (1956). The Stress of Life. New York; McGraw Hill Book Company. Stevens, S. S. and Galanter, E. H. (1957). Ratio scales and category scales for a dozen perceptual continua. Journal of Experimental Psychology, 54: 377. Theorell, T. and Rahe, R. H. (1971). Psychosocial factors and myocardial infarction. I. an inpatient study in Sweden. Journal of Psychosomatic Research, 15: 25.

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A scale to measure the stress of life events.

A comprehensive life event inventory suitable for questionaire or interviewer administration has been constructed. Two sets of matched scalings of the...
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