Factor analyses of the Suicidal Intent Scale (SIS) and the Risk-Rescue Rating Scale (RRRS): toward the identification of homogeneous subgroups of suicidal behaviors.

BACKGROUND: Suicidal behavior is a heterogeneous entity, determined by multiple factors. This heterogeneity has major implications for clinical management of patients and identification of risk factors. Our study aims at identifying homogeneous subgroups of patients with suicidal behavior.
METHODS: We used two validated questionnaires to assess the intent (Suicidal Intent Scale, SIS) and lethality (Risk-Rescue Rating Scale, RRRS) of the most severe suicide attempt in a sample of 608 patients recruited consecutively. We first explored the factorial structure of the two scales, using a principal component analysis, and then tested the relationship between sub-scores identified and subtypes of suicide attempts (violent, serious overdose) using a backward logistic regression.
RESULTS: A four-factor structure was retained for the SIS (conception, preparation, precautions and communication). The RRRS, for which a factorial structure has not been previously published, had a three-factor structure (medical damage, implementation and rescue conditions). This structure was valid, stable and clinically relevant. Serious suicide attempts were characterized by less communication and more precautions against discovery, whereas violent attempts were associated with higher risk acts. Neither violent nor serious attempts were characterized by more planning. LIMITATIONS: The SIS and RRRS were assessed retrospectively, and so could have been influenced by recall bias. Finally, censoring bias may have affected our results.
CONCLUSIONS: The characterization of suicidal behaviors using SIS and RRRS sub-scores constitutes a first step toward the identification of homogeneous subgroups of suicide attempters. Prospective studies are needed to test the predictive value of these sub-scores for subsequent suicidal acts. 2009 Elsevier B.V. All rights reserved.