Spectrum of suicidal behaviours in Edinburgh.

Until a few years ago, suicides and attempted suicides were regarded as a homogeneous group. Stengel, Cook, and Kreeger (1958) pointed out that they are two different but overlapping populations. The 'overlap' has been demonstrated by follow-up studies of attempted suicide which reveal only a small proportion who later committed suicide (0-3% to 22% depending upon the duration of follow-up), and by retrospective studies on com pleted suicides showing that only a small proportion of these had made previous attempts (8-6% to 33-3% in any unselected and consecutive series of suicides) (Dorpat and Ripley, 1967). Investigation of the full spectrum of suicidal behaviour requires the integration of detailed data on both suicides and attempted suicides occurring in the same population over the same period of time. The majority of researchers have studied the two patterns of behaviour in different populations or in different areas or at different times with ensuing problems of interpretation. Those few studies making a contem poraneous comparison have been restricted by difficulties in representative sampling among the attempted suicide population (Schmid and Van Arsdol, 1955, in Seattle; Farberow and Schneidman, 1961, in Los Angeles; Stengel etal, 1958, in London; Ropschitz and Ovenstone, 1968, in Halifax). This occurred either because the studies were carried out at a time when suicidal behaviour was a legal offence, as in London and Seattle, and precautions would be taken to conceal all but the most serious attempts, or the data were based on hospitalized cases and therefore likely to be biased towards persons requiring admission. The Los Angeles study did, however, include cases notified to them by the community physicians (from whom they had a 70 % response) and achieved what they called 'a fair but undoubtably conservative figure' for attempted suicides occurring over their research period. Sampling presents less difficulty in Edinburgh as 98 % of all suicidal attempts sent to, or presenting at, hospitals in the area are admitted to the Regional Poisoning Treatment Centre (RPTC) no matter how trivial the attempt. It has been demonstrated that 80% of the cases seen in general practice are also admitted and that the RPTC population is represen tative of those attempting suicide in Edinburgh (Kennedy, 1971). In most studies data relating to completed suicides have been obtained from coroners' records, which it is accepted under-report the problem. However, of more fundamental importance is the question whether under-reporting materially alters the characteristics of the suicide population. On this issue, a previous paper put forward the rationale for adopting a psychiatric instead of a legal approach to the matter of diagnosis (Ovenstone, 1972). However, a comparison of the two methods carried out on a series of Edinburgh deaths revealed that, to all intents and purposes, the officially recorded suicides provided a representative picture. Further analysis of those suicides ascertained by psychiatric means demonstrated that they were sub-divisible into two almost equal groups, distinguished on the basis of the presence or absence of a previous suicidal attempt or 'parasuicide'. Their character istics have been fully described in a separate paper (Ovenstone and Kreitman, in preparation). The present paper compares the same series of suicides, on a limited number of variables, with a group of attempted suicides admitted to the RPTC contemporaneously, to ascertain the common determinants of both types of behaviour, those factors which differentiate them, and the nature of the 'overlap'. Method Collection of Suicide Data