Suicidal Ideation and Later Suicide
To the Editor: In the December 2011 issue of the Journal, Posner et al. (1) state that “studies of risk factors predicting suicide consistently suggest that suicidal ideation and a history of suicide attempts are among the most salient risk factors for suicide.” We agree that there is strong evidence of a relationship between suicide attempts and subsequent suicide, but the association between expressed ideas of suicide and suicide is less clear.
The authors cite four papers supporting the presence of an association. The first reported mortality among suicide attempters but did not mention suicidal ideation (2). The next two found that high scores on the Scale for Suicide Ideation were associated with later suicide (3, 4). However, some items on this scale describe suicidal behavior rather than suicidal ideation, and it is the behavior items that are strongly associated with suicide (5). The fourth study found an association between suicidal ideation and suicide attempts, but it did not consider completed suicide (6).
In fact, two systematic meta-analyses have found weak associations between suicidal ideation and suicide. The first found that a modest association between suicide and suicidal ideation expressed by psychiatric inpatients might have been because of publication bias (7). Suicidal ideation did not independently predict inpatient suicide when depressed mood and previous suicide attempts were also considered (8). The second study found that suicidal ideas expressed in the hospital were weakly associated with suicide after discharge (9). We agree that there is a need to clarify the definitions of suicidal ideation and behavior. However, the presence of suicidal ideation, in the absence of a suicide attempt, has not been firmly established as a risk factor for suicide.
1. : The Columbia–Suicide Severity Rating Scale: initial validity and internal consistency findings from three multisite studies with adolescents and adults. Am J Psychiatry 2011; 168:1266–1277Link, Google Scholar
2. : Survival analysis of suicide risk after attempted suicide. Acta Psychiatr Scand 1995; 91:336–340Crossref, Medline, Google Scholar
3. : Suicide ideation at its worst point: a predictor of eventual suicide in psychiatric outpatients. Suicide Life Threat Behav 1999; 29:1–9Medline, Google Scholar
4. : Risk factors for suicide in psychiatric outpatients: a 20-year prospective study. J Consult Clin Psychol 2000; 68:371–377Crossref, Medline, Google Scholar
5. : Worst-point suicidal plans: a dimension of suicidality predictive of past suicide attempts and eventual death by suicide. Behav Res Ther 2003; 41:1469–1480Crossref, Medline, Google Scholar
6. : Incidence of suicide ideation and attempts in adults: the 13-year follow-up of a community sample in Baltimore. Psychol Med 2001; 31:1181–1191Crossref, Medline, Google Scholar
7. : Systematic review and meta-analysis of the clinical factors associated with the suicide of psychiatric in-patients. Acta Psychiatr Scand 2011; 124:18–29Crossref, Medline, Google Scholar
8. : The validity and utility of risk assessment for inpatient suicide. Australas Psychiatry 2011; 19:507–512Crossref, Medline, Google Scholar
9. : Risk factors for suicide within a year of discharge from psychiatric hospital: a systematic meta-analysis. Aust NZ J Psychiatry 2011; 45:619–628Crossref, Medline, Google Scholar
