Psychological Medicine, 1976, 6, 429-438
Completed suicide: a taxonomic analysis of clinical and social data CHRISTOPHER BAGLEY,1 SOLOMON JACOBSON AND ANN REHIN From the Department of Sociology, University of Surrey, Guildford and St Francis Hospital, Haywards Heath, Sussex SYNOPSIS A post mortem enquiry has been made into the social family and clinical circumstances of 50 individuals who, according to a coroner's verdict, killed themselves in Brighton. A dimensional analysis of the 123 variables thus collected suggested the possibility of three distinct types of suicide: 'depressive suicide', 'sociopathic suicide' and 'physical illness suicide'. The reliability of this typology has been checked by the analysis of 55 selected variables for a total of 193 cases considered by the same coroner. A cluster analysis has confirmed that the data contain at least three independent types of suicide. Some implications for the prevention of suicide are discussed.
The purpose of this paper is to present the results of a post-mortem enquiry into the social and clinical circumstances surrounding completed suicide in a series of 50 individuals; then to attempt some taxonomic analysis of the data so obtained; and then to carry out a test of the reliability of this taxonomy by additional taxonomic analyses on a further series of cases, in which a variety of verdicts (suicide, open and misadventure) have been reached by the same coroner. Remarkably little taxonomic work has been carried out on the phenomenon of suicide (W.H.O., 1968), and papers still appear in which the term 'suicide' applies to both completed and attempted suicide. Although Stengel (1964) has stressed the conceptual distinction between suicide and attempted suicide, it is clear too that there is in fact some overlap between these two phenomena (Stengel, 1972). However, even the validity of the term 'attempted suicide' has been called in question (Kreitman et al. 1969) since acts of self-injury may not have the clear intention of self-killing. What categorization of suicide that has been carried out has mostly been of an intuitive nature, rather than being based on the more formal methods of numerical taxonomy which have been used in biological sciences. Neuringer 1 Address for correspondence: Dr Christopher Bagley, Department of Sociology, University of Surrey, Guildford.
(1974), for example, lists nine such types put forward by various writers; the most frequent basis for these classifications seems to have been the inference about the motivation towards suicide. One problem in establishing a proper taxonomy of suicide has been the paucity of data available about people who have killed themselves. Although some suicides have clinically recorded histories of psychiatric disorder, this is by no means so in every case. The only systematic collection of social, clinical and demographic information about people who have apparently killed themselves is that undertaken by legal authorities. However, as the data reported in the present paper indicate, the range of information considered by English Coroners is rather limited, and is confined only to contemporary events of apparent aetiological significance. The only significant work on the classification of suicide by statistical methods appears to be that of the Edinburgh group (McCulloch et al. 1967; Ovenstone & Kreitman, 1974). Ovenstone and Kreitman studied a consecutive series of 106 suicides, classified by clinical rather than purely legal criteria. By a combination of clinical-descriptive and simple taxonomic methods the cases were divided into two groups (50 and 56), one having a history of parasuicide, the other having no such history. The
429
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Christopher Bagley, Solomon Jacobson and Ann Rehin
'parasuicide' group had an excess of individuals with a history of chronic social maladjustment or personal instability, unemployment, and heavy drinking. By contrast, the' no parasuicide' group consisted of individuals whose lives were relatively stable, their suicides being precipitated more often by the death of a significant other or by major physical illness; contact with family doctor or psychiatrist was much less frequent than in the former group. In the present study we approach this problem of taxonomy by more mathematically complex (but not necessarily better) methods than those employed by the Edinburgh workers.2
METHODS THE SPECIAL POST-MORTEM ENQUIRY
The aim of this part of the study was to interview relatives of a consecutive series of 50 cases on whom the Brighton coroner had recorded a verdict of suicide in an eight-month period, 1970-1, in order to obtain more information than is usually available about the suicide's circumstances, state of mind, and previous history. Inquests where (in the opinion of the police officer responsible) there was a possibility of a suicide verdict were attended by the research assistant who undertook the fieldwork. On the few occasions when this was not possible the coroner's records were consulted. In either case the witnesses who knew the deceased best were identified. If the suicide had lived in the Brighton area, these witnesses were approached after an appropriate interval - which was normally felt to be a minimum of three weeks since the suicide - to ask for their cooperation in agreeing to be interviewed. (Where the informant had no close personal connection with the suicide the interview sometimes took place sooner after the suicide.) The research worker usually called without notice, and if an interview was agreed to, it was more often than not given there and then; otherwise an appointment for another a Kreitman (personal communication, 1974) reports that a variety of advanced numerical techniques were in fact applied to the Edinburgh data. The final methods used in that study were the most parsimonious, and accorded reasonably well with the 'collapsing' of clusters in several different types of analysis into two groups.
time was made. Where possible the last person to see the suicide alive was interviewed, as well as those who apparently knew them best; on eight occasions the research worker was referred to someone not at the inquest who was likely to be helpful. In 43 out of the 50 cases at least one interview was completed. Anticipated difficulties in interviewing did not occur, and many respondents felt it was a relief to talk to someone who was not personally involved. The interview schedule used was one designed and piloted by the MRC Clinical Psychiatry Unit (Barraclough et al. 1974). This schedule seeks information on a wide variety of topics, including threats of suicide or discussion of death shortly before suicide; psychiatric symptoms which might have been apparent before suicide; family, personal and social history; medical and psychiatric history and current treatment; consultation with G.P.; extent of social integration or isolation; and bereavement. In addition to this schedule a questionnaire on health status, recent symptoms, drugs prescribed, etc., was sent to the G.P.S in the 47 cases in which they could be identified; all but two of these questionnaires were completed and returned. From both the above sources and, frequently, from the inquest, information about hospital treatment which the suicide had undergone at some time was obtained. Records were obtained from those hospitals where the suicides had been treated, and these were valuable additions to the knowledge obtained about each case. A case summary which incorporated the main items of information was then compiled for each case, and sent to three psychiatrists, each at a different hospital, for their diagnosis. In most cases they agreed substantially; where they differed, the view of the majority was accepted. A total of 88 informants were seen, in 70 interviews. In addition, 10 people were approached but either refused (8), or found themselves unable to complete the interview (2). All data collected were recorded in binary form (i.e. present or absent), and subjected to a variety of statistical investigations, including product moment correlations and more complex analyses derived from correlation matrices. The use of product moment techniques with binary data will probably not produce gross
431
A taxonomic analysis of clinical and social data TABLE 1 PRINCIPAL COMPONENTS OF VARIABLES FROM THE PSYCHOLOGICAL AUTOPSY OF SUICIDE
Loadings on principal components Variable Committed suicide at home Had made suicide threats or talked about death Had made preparations for suicide One or more previous suicide attempt Two or more previous suicide attempts Used a different method than in previous suicide attempt Medical care after a previous suicide attempt Psychiatric care after a previous suicide attempt Had a drinking problem Had poor sleep Had depressed mood Difficulties in concentrating or thinking Feelings of guilt or worldlessness Violent behaviour In trouble with the law Recent psychiatric symptoms Previous psychiatric symptoms Under care of psychiatrist at time of suicide Saw G.P. 1-4 weeks before suicide Saw G.P. 0-4 weeks before suicide No psychiatric drugs prescribed at time of suicide Barbiturates prescribed Hypnotics + other drugs prescribed Antidepressants prescribed Phenothiazines prescribed Drugs supplied by G.P. without seeing patient One previous spell of psychiatric treatment Two or more previous spells of psychiatric treatment Physical illness at time of suicide Chronic pain Physical handicap Chronic pain, or handicap at time of suicide With both parents till age 18 Reared by foster parents or relatives Reared in an institution Deprivation from under 5 Deprivation from 6-15 Deprivation from 0-15 Eldest child Subject had children Psychiatric treatment of family member Off work sick at time of suicide Unemployed Retired Downward social mobility in past two years Moved house since retiring Money worries Money shortage Owner occupier Private tenant Head of household Living alone Two or more in household Saw no relatives regularly Complained of not enough to do Complained of loneliness Broken romance or marriage Quarrel within last 48 hours Spouse or family member ill Stress (non-personal) Attended church regularly Active in clubs or associations
Prevalence (%) 64 52 56 26 12 14 25 22 10 64 68 36 50 8 18 20 48 14 28 48 24 22 12 20 12 12 20 32 40 14 18 26
38 14 14 22 12 28 16 52 8 16 10 30 8 20 26 26 38 34 58 34
62 36 — 26 16 10 18 78
22 32
A
B
C
—
— —
0-387 0-425 —
-0-335 -0-357 — - 0-427 — — —
— — — 0-530 0-612
0-330 0-531 — 0-748 0-505 0-332 0-418 0-456 0-406 0-387 — — 0-495 0-465 0-635 — — -0-585 0-467 0-600 — 0-532 0-867 0-893 — — — — — — — — — — 0-392 — — — 0-690 — 0-380
— 0-301 — — 0-520 -0-585 0-588 — — — 0-590 — 0-525 0-595
— -0-327 -0-495 — -0-525 -0-462
— — —
0-312 0-485 0-552 0-520 -0-612 -0-355 -0-367 — — — — 0-657 -0-632 -0-660 -0-605 -0-440 -0-520 -0-325 — -0-422 — -0-447 — -0-660
— 0-715 0-487 0-456 0-667 — —
0-321 0-775 — 0-750 0-528
-0-495 -0-401 0-415 -0-617
— -0-550 0-525 -0-682 — — — — — —
— 0-605 0-499 — — 0-456 — — —
NOTE. The following variables have no significant loadings on the three components above: alcohol with a suicide attempt; anxiety; hypochondria; delusions; saw G.P. in week before death; hypnotics alone prescribed; previous psychiatric treatment; reared by one parent; suicide in parent; mental illness of parent; suicide in sibling; mental illness of sibling; suicide of family member; only child; middle child; youngest child; council tenant; living in institution; related to head of household; saw two or more relatives regularly; no relatives within 10 minutes' journey; two or more relatives within 10 minutes' journey; saw friends in week before death; active with hobbies.
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Christopher Bagley, Solomon Jacobson and Ann Rehin
Simple tabulations of prevalence, interesting as they are, do not tell us about the more complex interrelations of the data. There are a variety of techniques available for such a purpose, but the most parsimonious is that of calculating the principal components of the data. These are, effectively, groups of variables which tend to covary together and with a reified 'component' to a significant degree. The numerical values in Tables 1 and 2 represent the degree of association with the component itself, but by and large significant variables on any component also tend to covary with one another to a significant degree. Thus, for example, variables 8 and 9 (medical and psychiatric care after a suicide attempt) are strongly correlated with one another, and with Component II itself. Each of the three components presented in Table 1 has a distinctive character. Component A loads strongly on having made a previous RESULTS suicide attempt, mental symptoms associated The prevalence of the 123 items analysed for the with depression, previous psychiatric symptoms 50 special enquiry cases is presented in Table 1. and treatment, taking antidepressant drugs, Correlations were calculated between the vari- being prescribed drugs unseen by G.p., being ables, and the principal components (unrotated) retired, an owner-occupier, having children, in were extracted from the very large correlation contact with relatives, active in clubs and matrix which resulted. Because of the relatively associations, but also complaining of boredom, small number of subjects studied, only compo- being aged over 60, recent mobility (usually nents having an eigenvalue of greater than two following retirement a move to the South Coast), were considered (see Hope, 1968, for a technical and coming from the Registrar General's Class description of the methods of analysis used). I and II (professional and managerial). Over half of the subjects had made suicide Component B has significant loadings on threats, and a quarter had made one or more making more than one previous suicide attempt, suicide attempt. Two-thirds had a depressed history of violent and criminal behaviour, mood, but only 14 % had been under the care previous psychiatric illness, being prescribed of a psychiatrist at the time of their death. phenothiazines, abnormal upbringing (with foster However, nearly half had seen their G.p. in the or institutional care, and social deprivation week before killing themselves, and three- from birth to fifteen years), being an eldest quarters were taking some form of psychotropic child, psychiatric illness in a family member, drugs (including barbiturates). A quarter were unemployment, downward social mobility, living suffering chronic pain or handicap at the time alone in rented accommodation, seeing no relaof their death. With regard to early develop- tives, being single, and younger (age less than 44) ment, only a quarter of subjects had had normal and coming from a lower class background. family life until they were aged 18. Loneliness Component C has high loadings on poor was a feature of the lives of a quarter of the sleep, depressed mood, recent consultation subjects, and the majority had experienced with G.P., being prescribed barbiturates, and stress of one kind or another. No less than 38 % using such drugs for suicide, being physically had killed themselves through an overdose of ill, or in chronic pain, off work sick or retired, barbiturates, a finding which, in the light of lonely, living alone, having suffered recent Barraclough's research (1974), has particular bereavement, aged over 46, and coming from a middle-class background. implications for the prescribing of this drug.
distortions and in terms of empirical validation seems to be well established (Bagley, 1975). In addition to the data derived from this special post-mortem study of suicides, data on a further 141 cases coming before the Brighton coroner during 1970-2 were studied. These included 83 cases on which a verdict of suicide had been recorded, 33 misadventure verdicts, and 25 'open' verdicts. Information from these cases was used as a check on the taxonomic types which emerged from the analysis of the 50 'special enquiry' cases. In a further analysis of these same data (Jacobson et al. 1976) we have established that the information on which the coroner bases his judgement appears to be valid, since largely similar prevalence levels for various indices were obtained in the special enquiry study of 50 suicides.
A taxonomic analysis of clinical and social data
This analysis has, then, suggested the possibility of three distinct types of suicide; type 1 characterized by clinical depression and longstanding psychiatric problems in older, middleclass people; type 2 characterized by sociopathic traits in younger individuals who have experienced early deprivation; and type 3 characterized by older individuals, enduring chronic pain or physical handicap. This typology makes intuitive sense, but there are a number of methodological problems to be solved before it can be accepted. First of all, the principal components analysis does not set out to classify individuals in discrete categories, but classifies variables pertaining to those individuals in a continuous rather than a categorical manner. Each individual in the analysis had a component score for each of the components considered: it is inherent in the statistical method used that these scores are relatively normally distributed. It is theoretically possible for an individual to have high, or low, scores on all of the three types of suicide which appear to emerge from the analysis. While the binary method of recording data implies some mutual exclusiveness (for example, in terms of age and social class), types 1 and 3 above could in fact refer to basically the same population of individuals. A second methodological problem is that we are working on small numbers, and with some variables which have low prevalences.3 Would the same typology emerge if the similar methods were applied to a larger sample of cases? We have tested this possibility by analysing data on a second sample of 83 cases of suicide, considering a more limited range of data (since for these cases we had to rely on the information available to the coroner, rather than on special enquiry data). The criteria used in selecting variables for this second analysis were (a) there should be complete information for all cases; and (b) the information should be positive in at least 10 % of cases, in order to give sufficient variation for a more reliable correlational analysis. Using these criteria 55 of the original 3 An additional technical difficulty of unreliable factors arises when the number of subjects is less than the number of variables (Rummel, 1970; Everitt, 1975). An analysis of 123 variables for only 50 cases would have no credence on its own, and Table 1 must be read in the context of the whole study, not simply by itself.
433
123 variables were considered. Four analyses were carried out: first of the original 50 special enquiry cases, considering only the 55 selected variables; then of 83 further cases on which the coroner had recorded a verdict of suicide; then of the two groups of suicides combined (133 cases in all); and finally of the 133 suicide cases, 25 open verdict cases, and 33 accident cases, considered together. We are thus, in the last analysis, able to consider the reliability of the original factors through the introduction of additional and apparently diverse case material, and to see in addition the extent to which some open and misadventure verdicts resemble the suicide cases in their modal characteristics. The results of the unrotated principal components analysis of the 50 special enquiry and 83 suicide cases were remarkably similar, so that we have omitted the results of the second analysis in Table 2. It will be seen, from inspection of Table 2, that there is stability of loadings for each component between the three analyses. Component I on this fresh analysis of 55 variables has significant loadings on death at home, poor sleep, recent contact with G.P., prescription of barbiturates, and death from barbiturate overdose, physical illness, chronic pain or handicap, being retired, widowed, aged over 60, and from a middle class background. This component is clearly similar to Component C which emerged in the analysis of the 123 variables for 50 special enquiry cases in Table 1. Component II in the analysis of 55 variables has strong affinities with Component A reported in Table 1 above. It loads strongly on previous attempted suicide and psychiatric treatment, depression and associated symptoms, prescription of antidepressants, usually prescribed unseen. However, age and social class do not load as strongly or consistently as in the analysis for the 123 variables for 50 cases. The third component in this new analysis bears, as expected, a resemblance to Component B in Table 1, and loads on being in trouble with the law, being unemployed, having money worries, living alone as a private tenant, single with few family contacts, being less than 29, from a lower class background, and moving into Brighton in recent years. It will be noted that adding the open and misadventure verdicts
18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29.
12. 13. 14. 15. 16. 17.
6. 7. 8. 9. 10. 11.
5.
1. 2. 3. 4.
TABLE 2
Death at home Suicide threats Suicide preparations One or more previous suicide attempts Psychiatric treatment after previous attempt Drinking problems Alcohol consumed before death Poor sleep Anxiety symptoms Depressed mood Difficulties concentrating or thinking Felt guilty or worthless Hypochondria Trouble with law Symptoms onset in last 3 months Had symptoms before Psychiatric treatment at time of death Saw G.P. 0-4 weeks before No psychiatric drugs prescribed Barbiturates prescribed Hynoptics +other drugs Anti-depressants Phenothiazines Drugs prescribed unseen Previous psychiatric treatment Physical illness Chronic pain or handicap Off sick Unemployed
0-365 0-262 0-250 0181
0-453 0067 0-335
0099 0057 0019 0122 0-480 0181 0-284 0027 0081 -0007 -0059 -0-235 0083 -0105 0-365 -0-323 0-527 0-407 -0041 -0039 0-220 -0024 0-285 0-534 - 0-203 -0174
0000 0022 0197 0-527 0157 0-254
-0-216 -0099 -0138 -0062 -0-251 -0184
-0-300 0-489 -0113 0-467 0-424 -0178 -0-343 0143 -0173 0-467 0-664 -0-319 -0-221 -0149 0-389 -0-326 0-504 0-353 -0082 -0086 0175 -0103 0-404 0-494 -0-202 -0-214
0062 0031 -0017 -0-207 -0182 0046
0024 -0036 0060 0-439 0178 0175
0144
0-372 0180 0-226
133 'suicide' cases
50 special enquiry cases
191 'suicide', 'open'and 'accident' cases
Component I
0-481 0-415 0-297 0103 0-210 0-530 0-457 0110 - 0-446 0148 0-222 0-415 0-386 0-328 0-639 -0-348 -0-217 0-359 0055
0-442 0077 - 0-540 0-343 0-384 0-396 0-338 0-442 0-502 -0163 0048 0-439 -0041
0-497 0124 0-213 0-510 0-375 0-581
0-544
0022 0-262 -0057
133 'suicide' cases
0-545 0-473 0-264 0101 0-456 0-446
0-386 -0041 0187 0-571 0-578 0-715
0-588
0149 0-321 -0-227
50 special enquiry cases
Component II
0-435 0-206 -0-465 0155 0-232 0-455 0-376 0-232 0-592 -0-272 -0-218 0084 -0188
0-441 0-519 0-312 0009 0075 0-364
0-474 -0054 -0091 0-589 0-491 0-622
0-481
-0051 0-453 0025
191 'suicide', 'open'and 'accident' cases
-0-351 -0-209 0091 0-378 -0-271 0095 -0-243 -0-236 -0017 0-283 0145 0177 -0-201 0049 0104 -0-247 -0133 -0058 0-399
-0098 -0184 0026 0-267 0-294 -0-202 -0-262 0-212 0150 -0182 -0025 0072 0078
-0123 0123 0061 -0019 -0-217 -0077
0085
-0123 -0057 - 0028
133 'suicide' cases
-0-328 -0130 0-362 0-356 -0-349 -0044
-0050 0027 -0-233 0107 -0116 -0143
0183
-0076 -0117 -0197
50 special enquiry cases
Component III
0082 -0013 -0-211 0-427 0081 - 0024 0013 0014 0-207 -0165 -0104 0072 0-362
-0184 -0-247 0068 0-358 -0-317 0-267
0045 0-511 0-575 0114 -0115 -0106
0153
-0041 -0012 -0191
191 'suicide'. 'open'and ' accident' cases
PRINCIPAL COMPONENTS OF SOCIAL AND CLINICAL VARIABLES IN 'SPECIAL ENQUIRY', 'SUICIDE', 'OPEN' AND 'ACCIDENT' CORONERS' CASES
30. 31. 32. 33. 34. 35. 36. 37. 38. 39. 40. 41. 42. 43. 44. 45. 46. 47. 48. 49. 50. 51. 52. 53. 54. 55.
191 'suicide', 'open' and 'accident' cases 0-612 0139 0-235 -0144 0-470 0-262 0043 -0-252 -0-533 -0130 0-655 0-274 -0-485 -0-425 -0103 0-665 0-470 -0170 -0118 -0-331 0-600 0-463 -0125 -0-334 0-379 -0024 9-8
133 'suicide' cases 0-630 0-252 0018 0000 0-443 0-281 0081 -CI98 - 0-492 -0-250 0-718 0-375 -0-436 -0-441 -0071 0-698 0-480 0-247 -0-260 - 0-260 0-612 0-330 -0093 -0-238 0-397 -0171 10-3
50 special enquiry cases
0-694 0-273 0094 -0046 0-410 0-305 0005 -0-254 -0-459 -0-216 0-786 0-464 -0-367 - 0-626 -0113 0-759 0-454 -0186 -0189 -0-240 0-562 0-354 -0035 -0-292 0-383 -0-394
12-2
Retired Money worries Owner-occupier Private tenant Head of household Living alone Spouse or family member ill Male Single Married Widowed Left suicide note Age less than 29 Age 30-45 Age 46-59 Age 60 or more Death from overdose Death from t»as Death from fall Death from other cause Death from barbiturates Social Class I and II Social Class III Social Class IV and V Had children Moved in last 5 years
% of variance
Component I
TABLE
i
133 'suicide' cases -0-259 0196 -0-310 0-242 -0182 -0072 0-239 -0042 0031 -0079 0000 0144 0079 0144 0169 -0-295 0162 -0-315 -0010 0011 0039 -0-368 0-324 0097 0055 0-364 8-3
-0019 0-254 -0137 0096 0168 -0057 0-305 -0122 - 0024 -0137 0122 -0-223 0012 -0044 0106 -C050 0-271 -0-360 0096 -0043 0144 -0-355 0-266 0-238 0-237 0-381 9-52
Component II 50 special enquiry cases
2 (cont.)
9-2
-0-345 0-240 -0110 0-009 -0091 - 0079 0-244 0023 -0103 0096 -0-206 0138 0112 0-293 0112 -0-359 0-334 -0-220 -0051 -0094 0169 -0140 0157 0068 -0117 0-319
191 'suicide', 'open'and 'accident' cases
6-9
-0031 0-560 -0-628 0-626 0092 0-430 - 0-479 0030 0-563 - 0-244 -0016 0196 0-385 0086 0068 -0192 0 270 - 0 188 - 0008 -0-240 -0124 -0-224 -0-256 0-490 -0-352 0-343
50 special enquiry cases
5-5
-0026 0-328 -0-670 0699 -0070 0-583 -0-368 0057 0-718 -0-315 -0142 0-245 0-365 -0053 0093 - 0069 0-243 0009 0043 -0-321 0118 -0-209 -0148 0-336 -0-220 0-334
133 'suicide' cases
Component III
60
-0061 0-301 -0-549 0-585 -0061 0-405 -0121 0136 0-469 -0144 -0044 -0180 0-313 -0096 0197 - 0066 C-237 -0-228 -0081 -0083 0-245 -0-201 0047 0-350 -0190 0-360
191 'suicide', 'open'and 'accident' cases
436
Christopher Bagley, Solomon Jacobson and Ann Rehin
changes the structure of this third component to some extent. Drinking problems, and the consumption of alcohol at the time of suicide load strongly on the component when the open and misadventure cases are included. In fact, as we have indicated in another presentation of these data (Jacobson et al. 1976) these two variables significantly differentiate the open and accident from the suicide cases. We have demonstrated that the three original components of suicide hypothetically identified in the analysis of data for 50 cases emerge in the analysis of a larger and more diverse population whose deaths have been considered by the coroner. It remains now to demonstrate the extent to which these three components represent distinct types of suicide which are taxonomically independent of one another. In order to do this we have used the method of cluster analysis. A variety of different statistical techniques are available for such analysis (Tryon & Bailey, 1970; Everitt, 1974). We have chosen the method of Euclidean cluster analysis described by Golder & Yeomans (1973). We hypothesized that in the calculation of four clusters the first three would resemble the three components or 'types' of suicide identified in the previous analyses, while the fourth would contain the residual categories not clearly assignable to any particular group. In test of this hypothesis, ten arbitrary clusters were selected on the basis of the similarity of each case with each other case in terms of the 55 variables. The 'nearest neighbour' cluster for each case was calculated and in a series of steps the ten clusters were systematically reduced to four. Thus the cases in each cluster showed a much stronger similarity to one another than to cases in any other cluster. The cluster grouping has been checked against the component analyses in the following way. 'High scores' on each case were taken from the component scores; for each component the top third of scorers, in the direction of the three types of suicide identified above, were selected. Thus 60 individuals had 'high' scores on Component I in Table 2; 64 had high scores on Component II; and 55 had high scores on Component III. Table 3 presents the comparison between the four clusters obtained, and high scores on the
three components. There is excellent concordance between the components and the clusters, in the direction hypothesized. Cluster 1 defines 48 individuals with high scores on Component I (23 with exclusively high scores on Component I); while 15 have high scores on Component II, and 14 on Component III. The first cluster, then, strongly represents the group of suicides who were older, experienced chronic pain and physical illness, had poor sleep, experienced bereavement, and used barbiturates to kill themselves. Cluster 2 is characterized by high scorers on Component III (32 cases, 21 of them exclusively) and represents the type of suicide involving unemployment, trouble with the law, and lower class background. Cluster 3 is most frequently characterized by high scorers on Component 11 (35 cases, 25 of them exclusively high scorers) and thus represents the type of suicide characterized by previous attempted suicide, current depression and associated symptoms, and previous psychiatric treatment. Cluster 4 is clearly a residual category, 48 out of the 54 cases falling into this category having high scores on none of the three components. However, less than half of these residual cases are those on which the coroner recorded an open or misadventure verdict, and 23 of the 33 misadventure cases, and 13 of the 25 open verdicts are included in the three types of suicide. From this evidence it would seem that clusters 1 and 2 in particular ('old and handicapped' and 'sociopathic') contain many cases upon which a verdict of suicide has not been recorded, but which are similar to the suicide cases in demographic and clinical characteristics.
CONCLUSIONS
There appear, in our Brighton data, to be at least three distinct types of suicide. The first is characterized by physical illness and chronic pain in older, middle-class individuals who are likely to be widowed, and lonely, suffering poor sleep and depressed mood, and who use the barbiturates prescribed by their G.P.S in order to kill themselves. From the point of view of prevention, general practitioners could clearly
A taxonomic analysis of clinical and social data
437
TABLE3 COMPARISON OF TAXONOMY OF SUICIDE, OPEN AND ACCIDENT VERDICTS BY PRINCIPAL COMPONENTS AND CLUSTER ANALYSIS
Cluster 1
Cluster 2
Cluster 3
Cluster 4
Horizontal totals
High scores on Component A B C A and B A and C Band C A, B and C
23 2 0 11 12 0 2
1 4 21 0 2 8 1
0 25 0 3 0 4 2
3 0 2 0 0 1 0
27 31 23 14 14 13 5
Modal characteristics High scores on Component A B C None
48 15 14 1
4 13 32 8
5 35 6 7
3 1 3 48
60 64 55 64
Open verdicts Accident verdicts
4 10
8 13
2 0
11 10
25 33
Total no. of cases
51
45
41
54
191
re-examine their prescribing habits, and check on the psychiatric significance of poor sleep combined with chronic pain and physical handicap. Clearly too there is a role for social welfare authorities in reducing the strains of physical handicap and the loneliness which results from bereavement. The second type is characterized by early disruption of family life, poor adjustment in the employment field, sociopathic traits, social isolation, and previous parasuicide. There are clear implications here for preventive work, including intervention in the 'cycle of deprivation' which can have important implications for suicidal behaviour (McCulloch & Philip, 1972). The third type is characterized by chronic depression, and previous suicide attempts in individuals who have long had contact with psychiatric services. Prevention here would probably involve advances in the care and treatment of depressive illness. Ovenstone and Kreitman's Edinburgh study (1974) identified two types of suicide, which resemble types one and two identified in the present study. It is possible that our third type was not identified in their study because of the different methods used for establishing taxonomy. It is possible too that because of its
importance as a place of both retirement and cheap accommodation for deviant individuals (Jacobson & Jacobson, 1972; Bagley et al. 1973) the profiles of suicide are likely to be different from those encountered in Edinburgh. In conclusion, it should be borne in mind that the typology of suicide presented here is a tentative one, because of the difficulties which abound in the use of multivariate analyses with psychiatric data (Everitt, 1975). Almost certainly there are now more distinct subtypes of suicide than the three identified in the present study. Ideally the typology should be checked on a fresh sample, using different methods of analysis. In defence of the proposed typology, however, is the fact that it has been validated by checking the variation of types of suicide across contrasted ecological areas (Bagley & Jacobson, 1976). We are grateful to the South Eastern Metropolitan Hospital Board for a grant to undertake this research; to the Brighton coroner, MrC. Webb, and his staff; and to Mr David Hitchin of the Centre for Social Research, Sussex University, for progamming advice. REFERENCES Bagley, C. (1975). On the validity of measures of association. American Journal of Sociology 80, 992-993. Bagley, C. & Jacobson, S. (1976). Ecological variation of three types of suicide. Psychological Medicine 6, 423-427.
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Bagley, C , Jacobson, S. & Palmer, C. (1973). Social structure and the ecological distribution of mental illness, suicide and delinquency. Psychological Medicine 3, 177-187. Barraclough, B. (1974). Are there safer hypnotics than barbiturates? Lancet i, 57-58. Barraclough, B., Bunch, J., Nelson, B. & Sainsbury, P. (1974). A hundred cases of suicide: clinical aspects. British Journal of Psychiatry 125, 355-373. Everitt, B. (1974). Cluster Analysis. Heinemann: London. Everitt, B. (1975). Multivariate analysis: the need for data, and other problems. British Journal of Psychiatry 126, 237-240. Golder, P. & Yeomans, K. (1973). The use of cluster analysis for stratification. Applied Statistics 22, 213-219. Jacobson, S. & Jacobson, D. (1972). Suicide in Brighton. British Journal of Psychiatry 121, 369-377. Jacobson, S., Bagley, C. & Rehin, A. (1976). Clinical and social variables which differentiate suicide, open and accident verdicts. Psychological Medicine 6, 417-412 Hope, K. (1968). Methods of Multivariate Analysis. University of London Press: London. Kreitman, N., Philip, A., Greer, S. & Bagley, C. (1969). Parasuicide. British Journal of Psychiatry 115, 746.
McCulloch, J. & Philip, A. (1972). Suicidal Behaviour. Pergamon: Oxford. McCulloch, J., Philip, A. & Carstairs, G. (1967). The ecology of suicidal behaviour. British Journal of Psychiatry 113, 313-319. Neuringer, C. (1974). Problems of assessing suicidal risk. In The Assessment of Suicidal Risk (ed. C. Neuringer). Charles Thomas: Springfield, III. Ovenstone, I. & Kreitman, N. (1974). Two syndromes of suicide. British Journal of Psychiatry 123, 597. Rummel, R. (1970). Applied Factor Analysis. Northwestern Universities Press: Evanston. Stengel, E. (1964). Suicide and Attempted Suicide. Pelican Books: London. Stengel, E. (1972). A survey of follow-up examinations of attempted suicides. In Suicide and Attempted Suicide (ed. J. Waldenstrom, T. Larsson & H. Bjungstedt). Nordiska Bokandelns: Stockholm. Tryon, R. & Bailey, D. (1970). Cluster Analysis. McGrawHill: New York. World Health Organization (1968). The Prevention of Suicide. World Health Organization: Geneva.
Completed suicide: a taxonomic analysis of clinical and social data CHRISTOPHER BAGLEY,1 SOLOMON JACOBSON AND ANN REHIN From the Department of Sociology, University of Surrey, Guildford and St Francis Hospital, Haywards Heath, Sussex SYNOPSIS A post mortem enquiry has been made into the social family and clinical circumstances of 50 individuals who, according to a coroner's verdict, killed themselves in Brighton. A dimensional analysis of the 123 variables thus collected suggested the possibility of three distinct types of suicide: 'depressive suicide', 'sociopathic suicide' and 'physical illness suicide'. The reliability of this typology has been checked by the analysis of 55 selected variables for a total of 193 cases considered by the same coroner. A cluster analysis has confirmed that the data contain at least three independent types of suicide. Some implications for the prevention of suicide are discussed.
The purpose of this paper is to present the results of a post-mortem enquiry into the social and clinical circumstances surrounding completed suicide in a series of 50 individuals; then to attempt some taxonomic analysis of the data so obtained; and then to carry out a test of the reliability of this taxonomy by additional taxonomic analyses on a further series of cases, in which a variety of verdicts (suicide, open and misadventure) have been reached by the same coroner. Remarkably little taxonomic work has been carried out on the phenomenon of suicide (W.H.O., 1968), and papers still appear in which the term 'suicide' applies to both completed and attempted suicide. Although Stengel (1964) has stressed the conceptual distinction between suicide and attempted suicide, it is clear too that there is in fact some overlap between these two phenomena (Stengel, 1972). However, even the validity of the term 'attempted suicide' has been called in question (Kreitman et al. 1969) since acts of self-injury may not have the clear intention of self-killing. What categorization of suicide that has been carried out has mostly been of an intuitive nature, rather than being based on the more formal methods of numerical taxonomy which have been used in biological sciences. Neuringer 1 Address for correspondence: Dr Christopher Bagley, Department of Sociology, University of Surrey, Guildford.
(1974), for example, lists nine such types put forward by various writers; the most frequent basis for these classifications seems to have been the inference about the motivation towards suicide. One problem in establishing a proper taxonomy of suicide has been the paucity of data available about people who have killed themselves. Although some suicides have clinically recorded histories of psychiatric disorder, this is by no means so in every case. The only systematic collection of social, clinical and demographic information about people who have apparently killed themselves is that undertaken by legal authorities. However, as the data reported in the present paper indicate, the range of information considered by English Coroners is rather limited, and is confined only to contemporary events of apparent aetiological significance. The only significant work on the classification of suicide by statistical methods appears to be that of the Edinburgh group (McCulloch et al. 1967; Ovenstone & Kreitman, 1974). Ovenstone and Kreitman studied a consecutive series of 106 suicides, classified by clinical rather than purely legal criteria. By a combination of clinical-descriptive and simple taxonomic methods the cases were divided into two groups (50 and 56), one having a history of parasuicide, the other having no such history. The
429
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Christopher Bagley, Solomon Jacobson and Ann Rehin
'parasuicide' group had an excess of individuals with a history of chronic social maladjustment or personal instability, unemployment, and heavy drinking. By contrast, the' no parasuicide' group consisted of individuals whose lives were relatively stable, their suicides being precipitated more often by the death of a significant other or by major physical illness; contact with family doctor or psychiatrist was much less frequent than in the former group. In the present study we approach this problem of taxonomy by more mathematically complex (but not necessarily better) methods than those employed by the Edinburgh workers.2
METHODS THE SPECIAL POST-MORTEM ENQUIRY
The aim of this part of the study was to interview relatives of a consecutive series of 50 cases on whom the Brighton coroner had recorded a verdict of suicide in an eight-month period, 1970-1, in order to obtain more information than is usually available about the suicide's circumstances, state of mind, and previous history. Inquests where (in the opinion of the police officer responsible) there was a possibility of a suicide verdict were attended by the research assistant who undertook the fieldwork. On the few occasions when this was not possible the coroner's records were consulted. In either case the witnesses who knew the deceased best were identified. If the suicide had lived in the Brighton area, these witnesses were approached after an appropriate interval - which was normally felt to be a minimum of three weeks since the suicide - to ask for their cooperation in agreeing to be interviewed. (Where the informant had no close personal connection with the suicide the interview sometimes took place sooner after the suicide.) The research worker usually called without notice, and if an interview was agreed to, it was more often than not given there and then; otherwise an appointment for another a Kreitman (personal communication, 1974) reports that a variety of advanced numerical techniques were in fact applied to the Edinburgh data. The final methods used in that study were the most parsimonious, and accorded reasonably well with the 'collapsing' of clusters in several different types of analysis into two groups.
time was made. Where possible the last person to see the suicide alive was interviewed, as well as those who apparently knew them best; on eight occasions the research worker was referred to someone not at the inquest who was likely to be helpful. In 43 out of the 50 cases at least one interview was completed. Anticipated difficulties in interviewing did not occur, and many respondents felt it was a relief to talk to someone who was not personally involved. The interview schedule used was one designed and piloted by the MRC Clinical Psychiatry Unit (Barraclough et al. 1974). This schedule seeks information on a wide variety of topics, including threats of suicide or discussion of death shortly before suicide; psychiatric symptoms which might have been apparent before suicide; family, personal and social history; medical and psychiatric history and current treatment; consultation with G.P.; extent of social integration or isolation; and bereavement. In addition to this schedule a questionnaire on health status, recent symptoms, drugs prescribed, etc., was sent to the G.P.S in the 47 cases in which they could be identified; all but two of these questionnaires were completed and returned. From both the above sources and, frequently, from the inquest, information about hospital treatment which the suicide had undergone at some time was obtained. Records were obtained from those hospitals where the suicides had been treated, and these were valuable additions to the knowledge obtained about each case. A case summary which incorporated the main items of information was then compiled for each case, and sent to three psychiatrists, each at a different hospital, for their diagnosis. In most cases they agreed substantially; where they differed, the view of the majority was accepted. A total of 88 informants were seen, in 70 interviews. In addition, 10 people were approached but either refused (8), or found themselves unable to complete the interview (2). All data collected were recorded in binary form (i.e. present or absent), and subjected to a variety of statistical investigations, including product moment correlations and more complex analyses derived from correlation matrices. The use of product moment techniques with binary data will probably not produce gross
431
A taxonomic analysis of clinical and social data TABLE 1 PRINCIPAL COMPONENTS OF VARIABLES FROM THE PSYCHOLOGICAL AUTOPSY OF SUICIDE
Loadings on principal components Variable Committed suicide at home Had made suicide threats or talked about death Had made preparations for suicide One or more previous suicide attempt Two or more previous suicide attempts Used a different method than in previous suicide attempt Medical care after a previous suicide attempt Psychiatric care after a previous suicide attempt Had a drinking problem Had poor sleep Had depressed mood Difficulties in concentrating or thinking Feelings of guilt or worldlessness Violent behaviour In trouble with the law Recent psychiatric symptoms Previous psychiatric symptoms Under care of psychiatrist at time of suicide Saw G.P. 1-4 weeks before suicide Saw G.P. 0-4 weeks before suicide No psychiatric drugs prescribed at time of suicide Barbiturates prescribed Hypnotics + other drugs prescribed Antidepressants prescribed Phenothiazines prescribed Drugs supplied by G.P. without seeing patient One previous spell of psychiatric treatment Two or more previous spells of psychiatric treatment Physical illness at time of suicide Chronic pain Physical handicap Chronic pain, or handicap at time of suicide With both parents till age 18 Reared by foster parents or relatives Reared in an institution Deprivation from under 5 Deprivation from 6-15 Deprivation from 0-15 Eldest child Subject had children Psychiatric treatment of family member Off work sick at time of suicide Unemployed Retired Downward social mobility in past two years Moved house since retiring Money worries Money shortage Owner occupier Private tenant Head of household Living alone Two or more in household Saw no relatives regularly Complained of not enough to do Complained of loneliness Broken romance or marriage Quarrel within last 48 hours Spouse or family member ill Stress (non-personal) Attended church regularly Active in clubs or associations
Prevalence (%) 64 52 56 26 12 14 25 22 10 64 68 36 50 8 18 20 48 14 28 48 24 22 12 20 12 12 20 32 40 14 18 26
38 14 14 22 12 28 16 52 8 16 10 30 8 20 26 26 38 34 58 34
62 36 — 26 16 10 18 78
22 32
A
B
C
—
— —
0-387 0-425 —
-0-335 -0-357 — - 0-427 — — —
— — — 0-530 0-612
0-330 0-531 — 0-748 0-505 0-332 0-418 0-456 0-406 0-387 — — 0-495 0-465 0-635 — — -0-585 0-467 0-600 — 0-532 0-867 0-893 — — — — — — — — — — 0-392 — — — 0-690 — 0-380
— 0-301 — — 0-520 -0-585 0-588 — — — 0-590 — 0-525 0-595
— -0-327 -0-495 — -0-525 -0-462
— — —
0-312 0-485 0-552 0-520 -0-612 -0-355 -0-367 — — — — 0-657 -0-632 -0-660 -0-605 -0-440 -0-520 -0-325 — -0-422 — -0-447 — -0-660
— 0-715 0-487 0-456 0-667 — —
0-321 0-775 — 0-750 0-528
-0-495 -0-401 0-415 -0-617
— -0-550 0-525 -0-682 — — — — — —
— 0-605 0-499 — — 0-456 — — —
NOTE. The following variables have no significant loadings on the three components above: alcohol with a suicide attempt; anxiety; hypochondria; delusions; saw G.P. in week before death; hypnotics alone prescribed; previous psychiatric treatment; reared by one parent; suicide in parent; mental illness of parent; suicide in sibling; mental illness of sibling; suicide of family member; only child; middle child; youngest child; council tenant; living in institution; related to head of household; saw two or more relatives regularly; no relatives within 10 minutes' journey; two or more relatives within 10 minutes' journey; saw friends in week before death; active with hobbies.
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Christopher Bagley, Solomon Jacobson and Ann Rehin
Simple tabulations of prevalence, interesting as they are, do not tell us about the more complex interrelations of the data. There are a variety of techniques available for such a purpose, but the most parsimonious is that of calculating the principal components of the data. These are, effectively, groups of variables which tend to covary together and with a reified 'component' to a significant degree. The numerical values in Tables 1 and 2 represent the degree of association with the component itself, but by and large significant variables on any component also tend to covary with one another to a significant degree. Thus, for example, variables 8 and 9 (medical and psychiatric care after a suicide attempt) are strongly correlated with one another, and with Component II itself. Each of the three components presented in Table 1 has a distinctive character. Component A loads strongly on having made a previous RESULTS suicide attempt, mental symptoms associated The prevalence of the 123 items analysed for the with depression, previous psychiatric symptoms 50 special enquiry cases is presented in Table 1. and treatment, taking antidepressant drugs, Correlations were calculated between the vari- being prescribed drugs unseen by G.p., being ables, and the principal components (unrotated) retired, an owner-occupier, having children, in were extracted from the very large correlation contact with relatives, active in clubs and matrix which resulted. Because of the relatively associations, but also complaining of boredom, small number of subjects studied, only compo- being aged over 60, recent mobility (usually nents having an eigenvalue of greater than two following retirement a move to the South Coast), were considered (see Hope, 1968, for a technical and coming from the Registrar General's Class description of the methods of analysis used). I and II (professional and managerial). Over half of the subjects had made suicide Component B has significant loadings on threats, and a quarter had made one or more making more than one previous suicide attempt, suicide attempt. Two-thirds had a depressed history of violent and criminal behaviour, mood, but only 14 % had been under the care previous psychiatric illness, being prescribed of a psychiatrist at the time of their death. phenothiazines, abnormal upbringing (with foster However, nearly half had seen their G.p. in the or institutional care, and social deprivation week before killing themselves, and three- from birth to fifteen years), being an eldest quarters were taking some form of psychotropic child, psychiatric illness in a family member, drugs (including barbiturates). A quarter were unemployment, downward social mobility, living suffering chronic pain or handicap at the time alone in rented accommodation, seeing no relaof their death. With regard to early develop- tives, being single, and younger (age less than 44) ment, only a quarter of subjects had had normal and coming from a lower class background. family life until they were aged 18. Loneliness Component C has high loadings on poor was a feature of the lives of a quarter of the sleep, depressed mood, recent consultation subjects, and the majority had experienced with G.P., being prescribed barbiturates, and stress of one kind or another. No less than 38 % using such drugs for suicide, being physically had killed themselves through an overdose of ill, or in chronic pain, off work sick or retired, barbiturates, a finding which, in the light of lonely, living alone, having suffered recent Barraclough's research (1974), has particular bereavement, aged over 46, and coming from a middle-class background. implications for the prescribing of this drug.
distortions and in terms of empirical validation seems to be well established (Bagley, 1975). In addition to the data derived from this special post-mortem study of suicides, data on a further 141 cases coming before the Brighton coroner during 1970-2 were studied. These included 83 cases on which a verdict of suicide had been recorded, 33 misadventure verdicts, and 25 'open' verdicts. Information from these cases was used as a check on the taxonomic types which emerged from the analysis of the 50 'special enquiry' cases. In a further analysis of these same data (Jacobson et al. 1976) we have established that the information on which the coroner bases his judgement appears to be valid, since largely similar prevalence levels for various indices were obtained in the special enquiry study of 50 suicides.
A taxonomic analysis of clinical and social data
This analysis has, then, suggested the possibility of three distinct types of suicide; type 1 characterized by clinical depression and longstanding psychiatric problems in older, middleclass people; type 2 characterized by sociopathic traits in younger individuals who have experienced early deprivation; and type 3 characterized by older individuals, enduring chronic pain or physical handicap. This typology makes intuitive sense, but there are a number of methodological problems to be solved before it can be accepted. First of all, the principal components analysis does not set out to classify individuals in discrete categories, but classifies variables pertaining to those individuals in a continuous rather than a categorical manner. Each individual in the analysis had a component score for each of the components considered: it is inherent in the statistical method used that these scores are relatively normally distributed. It is theoretically possible for an individual to have high, or low, scores on all of the three types of suicide which appear to emerge from the analysis. While the binary method of recording data implies some mutual exclusiveness (for example, in terms of age and social class), types 1 and 3 above could in fact refer to basically the same population of individuals. A second methodological problem is that we are working on small numbers, and with some variables which have low prevalences.3 Would the same typology emerge if the similar methods were applied to a larger sample of cases? We have tested this possibility by analysing data on a second sample of 83 cases of suicide, considering a more limited range of data (since for these cases we had to rely on the information available to the coroner, rather than on special enquiry data). The criteria used in selecting variables for this second analysis were (a) there should be complete information for all cases; and (b) the information should be positive in at least 10 % of cases, in order to give sufficient variation for a more reliable correlational analysis. Using these criteria 55 of the original 3 An additional technical difficulty of unreliable factors arises when the number of subjects is less than the number of variables (Rummel, 1970; Everitt, 1975). An analysis of 123 variables for only 50 cases would have no credence on its own, and Table 1 must be read in the context of the whole study, not simply by itself.
433
123 variables were considered. Four analyses were carried out: first of the original 50 special enquiry cases, considering only the 55 selected variables; then of 83 further cases on which the coroner had recorded a verdict of suicide; then of the two groups of suicides combined (133 cases in all); and finally of the 133 suicide cases, 25 open verdict cases, and 33 accident cases, considered together. We are thus, in the last analysis, able to consider the reliability of the original factors through the introduction of additional and apparently diverse case material, and to see in addition the extent to which some open and misadventure verdicts resemble the suicide cases in their modal characteristics. The results of the unrotated principal components analysis of the 50 special enquiry and 83 suicide cases were remarkably similar, so that we have omitted the results of the second analysis in Table 2. It will be seen, from inspection of Table 2, that there is stability of loadings for each component between the three analyses. Component I on this fresh analysis of 55 variables has significant loadings on death at home, poor sleep, recent contact with G.P., prescription of barbiturates, and death from barbiturate overdose, physical illness, chronic pain or handicap, being retired, widowed, aged over 60, and from a middle class background. This component is clearly similar to Component C which emerged in the analysis of the 123 variables for 50 special enquiry cases in Table 1. Component II in the analysis of 55 variables has strong affinities with Component A reported in Table 1 above. It loads strongly on previous attempted suicide and psychiatric treatment, depression and associated symptoms, prescription of antidepressants, usually prescribed unseen. However, age and social class do not load as strongly or consistently as in the analysis for the 123 variables for 50 cases. The third component in this new analysis bears, as expected, a resemblance to Component B in Table 1, and loads on being in trouble with the law, being unemployed, having money worries, living alone as a private tenant, single with few family contacts, being less than 29, from a lower class background, and moving into Brighton in recent years. It will be noted that adding the open and misadventure verdicts
18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29.
12. 13. 14. 15. 16. 17.
6. 7. 8. 9. 10. 11.
5.
1. 2. 3. 4.
TABLE 2
Death at home Suicide threats Suicide preparations One or more previous suicide attempts Psychiatric treatment after previous attempt Drinking problems Alcohol consumed before death Poor sleep Anxiety symptoms Depressed mood Difficulties concentrating or thinking Felt guilty or worthless Hypochondria Trouble with law Symptoms onset in last 3 months Had symptoms before Psychiatric treatment at time of death Saw G.P. 0-4 weeks before No psychiatric drugs prescribed Barbiturates prescribed Hynoptics +other drugs Anti-depressants Phenothiazines Drugs prescribed unseen Previous psychiatric treatment Physical illness Chronic pain or handicap Off sick Unemployed
0-365 0-262 0-250 0181
0-453 0067 0-335
0099 0057 0019 0122 0-480 0181 0-284 0027 0081 -0007 -0059 -0-235 0083 -0105 0-365 -0-323 0-527 0-407 -0041 -0039 0-220 -0024 0-285 0-534 - 0-203 -0174
0000 0022 0197 0-527 0157 0-254
-0-216 -0099 -0138 -0062 -0-251 -0184
-0-300 0-489 -0113 0-467 0-424 -0178 -0-343 0143 -0173 0-467 0-664 -0-319 -0-221 -0149 0-389 -0-326 0-504 0-353 -0082 -0086 0175 -0103 0-404 0-494 -0-202 -0-214
0062 0031 -0017 -0-207 -0182 0046
0024 -0036 0060 0-439 0178 0175
0144
0-372 0180 0-226
133 'suicide' cases
50 special enquiry cases
191 'suicide', 'open'and 'accident' cases
Component I
0-481 0-415 0-297 0103 0-210 0-530 0-457 0110 - 0-446 0148 0-222 0-415 0-386 0-328 0-639 -0-348 -0-217 0-359 0055
0-442 0077 - 0-540 0-343 0-384 0-396 0-338 0-442 0-502 -0163 0048 0-439 -0041
0-497 0124 0-213 0-510 0-375 0-581
0-544
0022 0-262 -0057
133 'suicide' cases
0-545 0-473 0-264 0101 0-456 0-446
0-386 -0041 0187 0-571 0-578 0-715
0-588
0149 0-321 -0-227
50 special enquiry cases
Component II
0-435 0-206 -0-465 0155 0-232 0-455 0-376 0-232 0-592 -0-272 -0-218 0084 -0188
0-441 0-519 0-312 0009 0075 0-364
0-474 -0054 -0091 0-589 0-491 0-622
0-481
-0051 0-453 0025
191 'suicide', 'open'and 'accident' cases
-0-351 -0-209 0091 0-378 -0-271 0095 -0-243 -0-236 -0017 0-283 0145 0177 -0-201 0049 0104 -0-247 -0133 -0058 0-399
-0098 -0184 0026 0-267 0-294 -0-202 -0-262 0-212 0150 -0182 -0025 0072 0078
-0123 0123 0061 -0019 -0-217 -0077
0085
-0123 -0057 - 0028
133 'suicide' cases
-0-328 -0130 0-362 0-356 -0-349 -0044
-0050 0027 -0-233 0107 -0116 -0143
0183
-0076 -0117 -0197
50 special enquiry cases
Component III
0082 -0013 -0-211 0-427 0081 - 0024 0013 0014 0-207 -0165 -0104 0072 0-362
-0184 -0-247 0068 0-358 -0-317 0-267
0045 0-511 0-575 0114 -0115 -0106
0153
-0041 -0012 -0191
191 'suicide'. 'open'and ' accident' cases
PRINCIPAL COMPONENTS OF SOCIAL AND CLINICAL VARIABLES IN 'SPECIAL ENQUIRY', 'SUICIDE', 'OPEN' AND 'ACCIDENT' CORONERS' CASES
30. 31. 32. 33. 34. 35. 36. 37. 38. 39. 40. 41. 42. 43. 44. 45. 46. 47. 48. 49. 50. 51. 52. 53. 54. 55.
191 'suicide', 'open' and 'accident' cases 0-612 0139 0-235 -0144 0-470 0-262 0043 -0-252 -0-533 -0130 0-655 0-274 -0-485 -0-425 -0103 0-665 0-470 -0170 -0118 -0-331 0-600 0-463 -0125 -0-334 0-379 -0024 9-8
133 'suicide' cases 0-630 0-252 0018 0000 0-443 0-281 0081 -CI98 - 0-492 -0-250 0-718 0-375 -0-436 -0-441 -0071 0-698 0-480 0-247 -0-260 - 0-260 0-612 0-330 -0093 -0-238 0-397 -0171 10-3
50 special enquiry cases
0-694 0-273 0094 -0046 0-410 0-305 0005 -0-254 -0-459 -0-216 0-786 0-464 -0-367 - 0-626 -0113 0-759 0-454 -0186 -0189 -0-240 0-562 0-354 -0035 -0-292 0-383 -0-394
12-2
Retired Money worries Owner-occupier Private tenant Head of household Living alone Spouse or family member ill Male Single Married Widowed Left suicide note Age less than 29 Age 30-45 Age 46-59 Age 60 or more Death from overdose Death from t»as Death from fall Death from other cause Death from barbiturates Social Class I and II Social Class III Social Class IV and V Had children Moved in last 5 years
% of variance
Component I
TABLE
i
133 'suicide' cases -0-259 0196 -0-310 0-242 -0182 -0072 0-239 -0042 0031 -0079 0000 0144 0079 0144 0169 -0-295 0162 -0-315 -0010 0011 0039 -0-368 0-324 0097 0055 0-364 8-3
-0019 0-254 -0137 0096 0168 -0057 0-305 -0122 - 0024 -0137 0122 -0-223 0012 -0044 0106 -C050 0-271 -0-360 0096 -0043 0144 -0-355 0-266 0-238 0-237 0-381 9-52
Component II 50 special enquiry cases
2 (cont.)
9-2
-0-345 0-240 -0110 0-009 -0091 - 0079 0-244 0023 -0103 0096 -0-206 0138 0112 0-293 0112 -0-359 0-334 -0-220 -0051 -0094 0169 -0140 0157 0068 -0117 0-319
191 'suicide', 'open'and 'accident' cases
6-9
-0031 0-560 -0-628 0-626 0092 0-430 - 0-479 0030 0-563 - 0-244 -0016 0196 0-385 0086 0068 -0192 0 270 - 0 188 - 0008 -0-240 -0124 -0-224 -0-256 0-490 -0-352 0-343
50 special enquiry cases
5-5
-0026 0-328 -0-670 0699 -0070 0-583 -0-368 0057 0-718 -0-315 -0142 0-245 0-365 -0053 0093 - 0069 0-243 0009 0043 -0-321 0118 -0-209 -0148 0-336 -0-220 0-334
133 'suicide' cases
Component III
60
-0061 0-301 -0-549 0-585 -0061 0-405 -0121 0136 0-469 -0144 -0044 -0180 0-313 -0096 0197 - 0066 C-237 -0-228 -0081 -0083 0-245 -0-201 0047 0-350 -0190 0-360
191 'suicide', 'open'and 'accident' cases
436
Christopher Bagley, Solomon Jacobson and Ann Rehin
changes the structure of this third component to some extent. Drinking problems, and the consumption of alcohol at the time of suicide load strongly on the component when the open and misadventure cases are included. In fact, as we have indicated in another presentation of these data (Jacobson et al. 1976) these two variables significantly differentiate the open and accident from the suicide cases. We have demonstrated that the three original components of suicide hypothetically identified in the analysis of data for 50 cases emerge in the analysis of a larger and more diverse population whose deaths have been considered by the coroner. It remains now to demonstrate the extent to which these three components represent distinct types of suicide which are taxonomically independent of one another. In order to do this we have used the method of cluster analysis. A variety of different statistical techniques are available for such analysis (Tryon & Bailey, 1970; Everitt, 1974). We have chosen the method of Euclidean cluster analysis described by Golder & Yeomans (1973). We hypothesized that in the calculation of four clusters the first three would resemble the three components or 'types' of suicide identified in the previous analyses, while the fourth would contain the residual categories not clearly assignable to any particular group. In test of this hypothesis, ten arbitrary clusters were selected on the basis of the similarity of each case with each other case in terms of the 55 variables. The 'nearest neighbour' cluster for each case was calculated and in a series of steps the ten clusters were systematically reduced to four. Thus the cases in each cluster showed a much stronger similarity to one another than to cases in any other cluster. The cluster grouping has been checked against the component analyses in the following way. 'High scores' on each case were taken from the component scores; for each component the top third of scorers, in the direction of the three types of suicide identified above, were selected. Thus 60 individuals had 'high' scores on Component I in Table 2; 64 had high scores on Component II; and 55 had high scores on Component III. Table 3 presents the comparison between the four clusters obtained, and high scores on the
three components. There is excellent concordance between the components and the clusters, in the direction hypothesized. Cluster 1 defines 48 individuals with high scores on Component I (23 with exclusively high scores on Component I); while 15 have high scores on Component II, and 14 on Component III. The first cluster, then, strongly represents the group of suicides who were older, experienced chronic pain and physical illness, had poor sleep, experienced bereavement, and used barbiturates to kill themselves. Cluster 2 is characterized by high scorers on Component III (32 cases, 21 of them exclusively) and represents the type of suicide involving unemployment, trouble with the law, and lower class background. Cluster 3 is most frequently characterized by high scorers on Component 11 (35 cases, 25 of them exclusively high scorers) and thus represents the type of suicide characterized by previous attempted suicide, current depression and associated symptoms, and previous psychiatric treatment. Cluster 4 is clearly a residual category, 48 out of the 54 cases falling into this category having high scores on none of the three components. However, less than half of these residual cases are those on which the coroner recorded an open or misadventure verdict, and 23 of the 33 misadventure cases, and 13 of the 25 open verdicts are included in the three types of suicide. From this evidence it would seem that clusters 1 and 2 in particular ('old and handicapped' and 'sociopathic') contain many cases upon which a verdict of suicide has not been recorded, but which are similar to the suicide cases in demographic and clinical characteristics.
CONCLUSIONS
There appear, in our Brighton data, to be at least three distinct types of suicide. The first is characterized by physical illness and chronic pain in older, middle-class individuals who are likely to be widowed, and lonely, suffering poor sleep and depressed mood, and who use the barbiturates prescribed by their G.P.S in order to kill themselves. From the point of view of prevention, general practitioners could clearly
A taxonomic analysis of clinical and social data
437
TABLE3 COMPARISON OF TAXONOMY OF SUICIDE, OPEN AND ACCIDENT VERDICTS BY PRINCIPAL COMPONENTS AND CLUSTER ANALYSIS
Cluster 1
Cluster 2
Cluster 3
Cluster 4
Horizontal totals
High scores on Component A B C A and B A and C Band C A, B and C
23 2 0 11 12 0 2
1 4 21 0 2 8 1
0 25 0 3 0 4 2
3 0 2 0 0 1 0
27 31 23 14 14 13 5
Modal characteristics High scores on Component A B C None
48 15 14 1
4 13 32 8
5 35 6 7
3 1 3 48
60 64 55 64
Open verdicts Accident verdicts
4 10
8 13
2 0
11 10
25 33
Total no. of cases
51
45
41
54
191
re-examine their prescribing habits, and check on the psychiatric significance of poor sleep combined with chronic pain and physical handicap. Clearly too there is a role for social welfare authorities in reducing the strains of physical handicap and the loneliness which results from bereavement. The second type is characterized by early disruption of family life, poor adjustment in the employment field, sociopathic traits, social isolation, and previous parasuicide. There are clear implications here for preventive work, including intervention in the 'cycle of deprivation' which can have important implications for suicidal behaviour (McCulloch & Philip, 1972). The third type is characterized by chronic depression, and previous suicide attempts in individuals who have long had contact with psychiatric services. Prevention here would probably involve advances in the care and treatment of depressive illness. Ovenstone and Kreitman's Edinburgh study (1974) identified two types of suicide, which resemble types one and two identified in the present study. It is possible that our third type was not identified in their study because of the different methods used for establishing taxonomy. It is possible too that because of its
importance as a place of both retirement and cheap accommodation for deviant individuals (Jacobson & Jacobson, 1972; Bagley et al. 1973) the profiles of suicide are likely to be different from those encountered in Edinburgh. In conclusion, it should be borne in mind that the typology of suicide presented here is a tentative one, because of the difficulties which abound in the use of multivariate analyses with psychiatric data (Everitt, 1975). Almost certainly there are now more distinct subtypes of suicide than the three identified in the present study. Ideally the typology should be checked on a fresh sample, using different methods of analysis. In defence of the proposed typology, however, is the fact that it has been validated by checking the variation of types of suicide across contrasted ecological areas (Bagley & Jacobson, 1976). We are grateful to the South Eastern Metropolitan Hospital Board for a grant to undertake this research; to the Brighton coroner, MrC. Webb, and his staff; and to Mr David Hitchin of the Centre for Social Research, Sussex University, for progamming advice. REFERENCES Bagley, C. (1975). On the validity of measures of association. American Journal of Sociology 80, 992-993. Bagley, C. & Jacobson, S. (1976). Ecological variation of three types of suicide. Psychological Medicine 6, 423-427.
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Bagley, C , Jacobson, S. & Palmer, C. (1973). Social structure and the ecological distribution of mental illness, suicide and delinquency. Psychological Medicine 3, 177-187. Barraclough, B. (1974). Are there safer hypnotics than barbiturates? Lancet i, 57-58. Barraclough, B., Bunch, J., Nelson, B. & Sainsbury, P. (1974). A hundred cases of suicide: clinical aspects. British Journal of Psychiatry 125, 355-373. Everitt, B. (1974). Cluster Analysis. Heinemann: London. Everitt, B. (1975). Multivariate analysis: the need for data, and other problems. British Journal of Psychiatry 126, 237-240. Golder, P. & Yeomans, K. (1973). The use of cluster analysis for stratification. Applied Statistics 22, 213-219. Jacobson, S. & Jacobson, D. (1972). Suicide in Brighton. British Journal of Psychiatry 121, 369-377. Jacobson, S., Bagley, C. & Rehin, A. (1976). Clinical and social variables which differentiate suicide, open and accident verdicts. Psychological Medicine 6, 417-412 Hope, K. (1968). Methods of Multivariate Analysis. University of London Press: London. Kreitman, N., Philip, A., Greer, S. & Bagley, C. (1969). Parasuicide. British Journal of Psychiatry 115, 746.
McCulloch, J. & Philip, A. (1972). Suicidal Behaviour. Pergamon: Oxford. McCulloch, J., Philip, A. & Carstairs, G. (1967). The ecology of suicidal behaviour. British Journal of Psychiatry 113, 313-319. Neuringer, C. (1974). Problems of assessing suicidal risk. In The Assessment of Suicidal Risk (ed. C. Neuringer). Charles Thomas: Springfield, III. Ovenstone, I. & Kreitman, N. (1974). Two syndromes of suicide. British Journal of Psychiatry 123, 597. Rummel, R. (1970). Applied Factor Analysis. Northwestern Universities Press: Evanston. Stengel, E. (1964). Suicide and Attempted Suicide. Pelican Books: London. Stengel, E. (1972). A survey of follow-up examinations of attempted suicides. In Suicide and Attempted Suicide (ed. J. Waldenstrom, T. Larsson & H. Bjungstedt). Nordiska Bokandelns: Stockholm. Tryon, R. & Bailey, D. (1970). Cluster Analysis. McGrawHill: New York. World Health Organization (1968). The Prevention of Suicide. World Health Organization: Geneva.
