Cross-Cultural Adaptation and Psychometric Evaluation of the Suicidal Intrusions Attributes Scale (SINAS) in Iranian Adolescents With Suicidal Ideation

Abstract

Suicidal intrusive thoughts are unwanted, recurrent mental images of suicide that carry considerable weight in suicide-risk evaluation. Yet, few brief screening instruments exist for assessing them in high-risk groups. This study examined the psychometric properties and cross-cultural adaptation of the Suicidal Intrusions Attributes Scale (SINAS) for evaluating the severity and characteristics of these thoughts in adolescents. The sample comprised 623 Iranian adolescents (aged 14–19 years) with current suicidal ideation, drawn from 12,000 students in Lorestan Province who were first screened with the Suicide Probability Scale and then selected through random cluster and purposive sampling. Instruments included the 10-item SINAS, the Suicide Probability Scale, the Beck Hopelessness Scale, the Hospital Anxiety and Depression Scale, a brooding-rumination measure, and a fearlessness-about-death measure. We examined age and gender as grouping variables to evaluate measurement invariance. Data were analysed in SPSS 26/27 and JASP 0.19.1. Exploratory factor analysis (n = 323) identified a single-factor structure explaining 50.48% of the variance; confirmatory factor analysis (n = 300) supported this one-factor structure with good fit. Internal consistency was satisfactory (Cronbach's α = 0.91; McDonald's ω = 0.89) and convergent and discriminant validity were acceptable. SINAS also discriminated well between adolescents with suicidal ideation and those with a history of a suicide attempt (AUC = 0.876). Convergent validity was supported by significant positive correlations between SINAS scores and suicide probability (r = 0.724), hopelessness (r = 0.698), anxiety (r = 0.663), rumination (r = 0.578), depression (r = 0.569) and fearlessness about death (r = 0.167; all p < 0.001). CFA confirmed a unidimensional structure, with measurement invariance across gender and age. These findings indicate that the SINAS demonstrates acceptable reliability and validity among Iranian adolescents with suicidal ideation and represents a suitable instrument for screening suicidal intrusive thoughts in research and clinical settings.