Life changes and social group in relation to illness onset

LIFE. CHANGES

AND TO

SOCIAL

ILLNESS

GROUP

TN RELATIOT’!

ONSET”

VILH~ J. MATTILA and RAIM~ K. R. SALO~~AWAS (Received

I Ocfoher 1976)

SEVERAL studies carried out in Scandinavia [l-6] have emphasized psychosocial stress as one of the etiological factors of illnesses. The concept of stress initially defined by Selye (general adaptation syndrome) [7] has been later extended to include the area of all sociological, psychological and physiological problems with which an individual has been burdened with demands exceeding his potential ability for adaptation [8]. Theorell [4] divided stress into a chronic and an acute form. By the latter he means diverse life changes experienced by an individual. Holmes and Rahe [9] have developed a so-called SRE questionnaire (Schedule of Recent Experience) to quantify the degreee of adaptation required by diverse life events. A certain number of scores or LCU value (Life Change Unit) has been in this way secured for each event. In numerous retrospective and prospective studies a gradual build-up in life change intensity has been observed to occur during the course of several months prior to the onset of an illness and observed to remain after the illness for some time at a level higher than normal [5-6, 10-151. However, significant findings have not been obtained in all prospective studies carried out by Rahe’s school [16-l 71. On the other hand many other observations suggest that the nature of life changes, in particular life events not wished for, and the tendency for the individual to adopt the sick role contribute more to the explanation of request for treatment than objective incidents of change per SE [ 1g-241. Besides life changes, a low social status has been regarded as a stress factor, particularly as a chronic one [25]. In several studies [26-281 both physical and mental illnesses have been found to be more common in lower social groups. Since in only a few investigatons [29-301 has attention been focused on the interrelations between social status, life changes and the onset of illness, the examination of these relationships was chosen as the primary object of this pilot study. The point of departure in the present investigation is the hypothesis that both belonging to a low social group and experiencing numerous life changes are stress factors that are in a non-specific way conducive to susceptibility to illnesses. MATERIAL AND METHODS A large place of employment was chosen as the site of the investigation. It was situated in Turku and had good health facilities provided by the employer which had been in operation for a long time. The method proposed was to gather medical data about the subjects from the records of the occupational health centre as a separate source of information from the subjects’ own reports on the events of their lives. From those employees between the ages 20 and 49 who had been working at the place for the last three years in succession a random sample of 200 people was taken. A questionnaire about social background and a modified SRE questionnaire [5, 9, 311 was mailed to them. The subjects were asked about the life changes which had occured in the course of the last three years divided into three-month intervals. The LCU scale employed in the investigation was constructed using a duplicate sample taken from the same population [32]. *Department of Psychiatry and Department of Public Health, 111 Clinical Institute, University of Turku. Kurjenmgentie 4, 20700 Turku 70, Finland. 167

The number of visits to the occupational health centre, days spent on sick-leave and asscssmcnt\: made by the investigators about the possible eventuality of a chronic illness based on the data derived from the health records were used as variables relating to illness. The subjects were requested to return the questionnaires by post. An elfort was made to contact, by telephone or in person. those who failed to answer and those whose answers were in obvious variance v, ith the facts. Due to missing or incomplete information 35 cases were excluded. Those excluded did not differ in a statistically significant way regarding age, sex, occupation and illness incidence from those whose answers had been accepted as sufficient. However, among the persons excluded there were nearly significantly (p < 0.05) more single and divorced people. In the remaining 165 subjects there were 46 men. 84.2 y/c:of the subjects were married, 9.7 “/, single and 4.9 “i, divorced. As the criterion of social group (in the following, referred to as “occupation”) Rauhala’s g-stage scale [33] designed according to ranking the prestige of occupations was used. 61.8 “,/, of the subjects belonged to the three lowest groups, mainly unskilled labourers, and only 3.0:); to the three highest groups, mainly those with university education. The largest age group were those aged from 40 to 49 who totalled 46.1 % of the sample.

RESULTS A. Age. social class. life c1tattge.c ad

illnesses

drtr-ittg the three-year

period

The relationship between social background variables and life changes have been dealt with and discussed elsewhere [32]. In the material that follows, background variables and the life change totals for the whole three years’ research period are investigated for their relationships to the sums of visits to the occupational health centre and sick-leave days. The intercorrelations for these variables (Pearson product moment correlation coefficients) are recorded in Table I. TABLE

I.-THEINTERCORRELATIONSFORBACKGROUND VARIABLES, LCU AND THEIR LEVELS OF SIGNIFICANCE

--__~~ Age Occupation’? LCU scores Chronic illness Sick calls Sick leave tLow

value

Occupation

Age I .oo z+:\

-m0.05 I .oo :r1: :k%!_ ‘9 * :::

-

low social

status:

* p .’ 0.05;

SCORESANDILLNESSVARIABLES

Chronic LCU scores illness ~~. ___~____~~ -0.24 0.13 0.25 0.14

I .oo

Sick calls ___ ___~ - 0.04 ~0.36 0.04 0.5x I .oo ***

0.08 I .oo

+4 * >?;i:‘,k

Sick leave 0.1 I 0.23 0.00 0.51 0.57 1.00

** p .’ 0.01 ; *** p c: 0.001.

Considering the figures obtained it appears that life changes are more common among young people and those belonging to higher occupational groups. The occupation correlates fairly negatively with all the illness variables whereas between life changes and illness criteria, correlations are not found. Since it seemed possible that the connection between life changes and illnesses might be covered by the covariation of the variables, regression analyses were carried out using two different models of analysis separately. In the first (fixed) model variables were included in the analysis in the following order established before analysis: age, occupation, chronic illness, life change scores. In the other model (open) the best explanatory variables were chosen by computer. These regression analyses explaining health centre visits and sick leave are provided by Tables 225. The levels of significance are expressed in the same way as before. The increases in the proportion of the variance and accumulated proportions of the variance (F) recorded in the tables refer to increases when a new variable has been included in the model whereas the regression coefficients refer to coefiicientc within the framework of a completed model. TABLE Z.---THE FIXED REGRESSION MODEL

Explanatory Age Occupation Chronic illness LCU scores

variable

AND NUMBER

OF HEALTH

Regression coefficient

Increase in proportion of the variance

m-o.093 ---2.294 7.836 0.008

0.001

0.133**+ 0.263”:** 0.011

(‘ENTRL VISllS

Accumulated proportionofthevariance(R’) .._ ._ .~~~~

0.001 0.135*** 0,397**>!. 0.409***

~._

Life changes and social group in relation to illness onset TABLE 3.--THEPIXED

REGRESSION MODEL

Regression coefficient 0.118 --7.R06 43,860 0.059

Explanatory variable Age Occupation Chronic illness LCU scores

TABLET.-THEOPENREGRESSIONMODEL

TABLE 5.-THEOPEN

Explanatory Chronic illness Occupation LCU scores Age

AND NUMBEROFHEALTH

Increase in proportion of the variance 0.334*** 0.050*** 0.019* 0.004

REGRESSION MODEL

Regression coefficient

variable

AND SICK LEAVE

Increase in proportion of the variance 0.012 0.052** 0.206*** 0.014

Regression coefficient 7.836 -~ 2.294 0.008 -0.097

Explanatory variable Chronic illness Occupation LCU scores Age

Accumulated proportionofthevariance(R*) 0.012 0.064** 0.271*** 0.285*** CENTRE VISITS

Accumulated proportionofthevariance(R?) 0.334*** 0.385*** 0.404*** 0.409***

AND SICK LEAVE

Increase in proportion of the variance

43.861 -7.806 0.059 0.778

169

Accumulated proportionofthevariance(R2)

0.251*** 0.012 0.009 0.007

0.257*** 0.269*** 0.278*** 0.285***

The above tables show that age has little explanatory value. Chronic illness proved to be the most significant explanatory variable. Occupation accounted significantly for the variance of the illness all along, with the exception of sick-leave in the open regression model, ranging from l-13’%. Life changes accounted for l-2% not, however, achieving a statistically significant level. B. The temporal

relationship

between life changes and ilbtesses

For the purpose of comparing life changes and the time of the onset of illness an illness period was determined to be a three-month int:rval during which the subje:t had either visited the occupational health centre at least three times or been on sick leave for three days. The temporal distribution for life change scores based on the entire material is presented in Fig. I. Life changes are observed to increase prior to the onset of illness and to reach a peak during the illness period. The increases observed prior to the illness period are not, however statistically signiticant (p > 0.05).

FIG. I.-The

temporal distribution

of life change scores.

The temporal distributions for life change scores according to age are illustrated in Fig. 2. In the youngest age group, an increase in stages in LCU scores prior to the illness period can be seen. The values of LCU scores of the illness period are, however, lower than those of the interval immediately preceding it.

170

VILHO

FIG. 2.-The

J.

R~ATTII

temporal distribution

A nnd

RAIMO

K. R. Sat

OK~ASGAS

of life change scores according to age groups.

The distributions according to occupr\tion are given in Fig. 3. In the six highest occupational groups (mainly skilled labourers and professional workers) slight build-up in life change scores is to be seen. The tendency for the life change scores to increase stemvise is more pronounced if the four highest groups are considered separately.

24 PI

--J

L

Tk

6

occupoi

tllgr:c>t groups

N= 63

The 3 occupat

lowest groups

N : 102

FIG;.

3.-The

temporal distribution

of life change scores according to occupntional

groups.

The distributions according to chronic illness are provided in Fig. 4. Life change scores were found to increase a little prior to the illness period in those not having chronic illness, as expected. None of these pre-illness increases in LCU values were statistically significant, however (p > 0.05).

171

FIG. 4.

The temporal distribution

of life change scores according to the general state of health

DISCUSSION

Investigation of the intercorrelations and the results derived fromregression analysis is hampered a little by the fact that all intercorrelations are not linear. To some extent this has contributed to the low correlation between age and illnesses. Both health centre visits and sick-leaves were least likely to be found in the middle age group; in the younger subjects, there were a greater number of visits than in the older ones, referring to sick-leave the converse was true. This finding differs from the general population in which a rather clear-cut positive correlation between age and illnesses has been observed [34] primarily due to the fact that the present research subjects were rather healthy, relatively young and had high occupational stability. Social group and illnesses

A low occupational status was found to be related to both chronic illness and health centre visits and sick-leave. A low social group was associated with illnesses as well in the cases in which education and income level were used as the criterion for social group status. The finding seems to lend support to the hypothesis that a greater number of stress factors would accumulate in a low social status rather than in the higher ones. A finding in itself important and understandable was that chronic illnesses contributed in the most significant way to the explanation of illness behaviour (health centre visits and sick leave). Chronic illnesses explain illness behaviour not only by itself but possibly also in combination with low occupational status. In accordance with the original hypothesis this seems, then, to suggest that a greater number of stress factors, including those which increase susceptibility to chronic illnesses, would accumulate in the lower social groups.

172

VILHO J. MAITILA

and RAIMU K. R. SALWANGAS

Here, two qualifications must be made, however. Firstly, it is possible that chronic illnesses have led to lower occupational status. On reviewing the health records this does not seem likely, however. Secondly, the method of investigation may have contributed toward the finding that low occupational status was observed to have less explanatory value in the case of sick-leave than in health centre visits particularly when chronic illness was held constant (open regression model) since those belonging to higher occupational groups may use more than others medical services offered outside the working place.

The regression analysis revealed the previously lacking explanatory capacity ot life changes. The highest increase in the proportion of the variance (1.9 “/;) was obtained in visits using the open model. The finding is to a great extent consistent with the result obtained by Thurlow [21] with a population of labourers. While methodical factors might have partly influenced the low life change rates obtained in the present study [32], it is to be noted that the explanatory degree of life changes in other studies too, have been only about 30; or less [35], provided that the illness criteria have been similar to those employed in the present study. On the other hand, when various kinds of symptom scales have been used as the illness criteria, considerably higher rates for explanatory capacity have been obtained (e.g. [36]). In the investigation into temporal relationships, the most pronounced theoryconsistent accumulations of life change scores prior to illness were obtained in the young and healthy subjects and to some degree as well in those belonging to the higher occupational groups. For this part of the study the findings correspond with the results obtained by Rahe even though differences in LCU levels failed to meet the criteria of statistical significance. In other social status criteria than occupation regular temporal relationships were not found. The most clear-cut findings were usually obtained from those respondent groups who had the greatest number of life changes. Considering the above it appears that an increase to some degree in life changes occurs prior to an episode of illness or at least in close peri-illness proximity to it even though this tendency for accumulation is in general rather slight and is easily masked by other factors. Rahe has conducted most of his retrospective as well as his prospective studies using enlisted naval men who participated, for example, in the Vietnam war. His research sample thus consists of young and healthy people and in the present study the most distinct findings were obtained with people in this category. As for the retrospective studies performed by other researchers, the positive and theory-consistent temporal relationships found in them might be interpreted in such a way that illnesses may have been used by the subjects as anchors for holding on to and registering life changes. This may have been the case particularly in myocardial infarction studies. This view is supported by the findings of the new and extensive study performed by Theorell’s team [37] in which positive correlations could not be established in the case of myocardial infarction but proved to be significant in prediction of neuroses. Obviously factors other than life changes have a more decisive significance in the genesis of illnesses. Life changes may be not only stress producing agents but also

Lift changes and social group in relation to illness onset

173

consequences of an attempt to adapt to stress. In this regard, the material in the prospective studies by Rahe seems to be biased in the selection of the sample. It is easy to assume that only people of a certain type volunteer to live the life of a naval cnlistee in Vietnamese waters. The present research subjects are essentially different from Rahe’s subjects as they consist of rather stable working people who are older than Rahe’s subjects. In future research it would be important to pay attention to the interrelationships between psychological constitution, life changes and illnesses seeking at the same time to control the effects of social background factors. SUMMARY

For the purpose of examining interrelationships between life changes, social background variables and the onset of illness a random sample comprising 200 people was taken from those employees of a large working place who were between the ages 20 and 49 and who had worked there for the last three years successively. A questionnaire concerning social background information and a modified SRE questionnaire (Schedule of Recent Experience) in which the subjects were asked about their life changes over the last three years were mailed to them. This data was compared to the health records furnished by the occupational health centre. An effort was made to contact, by telephone or in person, those who failed to answer as well as those whose answers were in obvious variance with the facts. Subjects who answered adequately numbered 165. Both acute and chronic illnesses were found to be in a statistically significant way more common in the lower occupational groups than in the higher ones. Between life change totals based on the three years and the illnesses there was a low and statistically non-significant dependence (life changes accounted for the variance of illness at a level of 1.9% at the highest). In analysis of temporal relationships, low non-significant increases in life changes prior to a period of illness were found particularly among the young and healthy subjects and in those belonging to the higher social groups. In the discussion, these results have been considered from the methodological and theoretical point of view. REFERENCES

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