Psychometric Evaluation of Sinhala and Tamil Measures of Suicidal Behavior and Interpersonal Suicide Risk Constructs...

Valid and culturally appropriate instruments are essential for suicide research and risk screening. This study evaluated the psychometric properties of the Sinhala and Tamil versions of the Suicide Behaviors Questionnaire-Revised (SBQ-R), Interpersonal Needs Questionnaire-10 (INQ-10), and Acquired Capability for Suicide Scale-Fearlessness About Death (ACSS-FAD), which assess constructs of the Interpersonal Theory of Suicide (IPTS).

In this cross-sectional study, 551 university students (409 Sinhala-speaking, 142 Tamil-speaking) and 98 patients presenting with self-harm completed the measures. Structural validity, reliability, convergent validity, known-group validity, measurement invariance, and receiver operating characteristic analyses were performed.

The SBQ-R demonstrated a unidimensional structure, good internal consistency (ordinal α = 0.86-0.92), language and gender invariance, and satisfactory convergent and known-group validity. The original seven-item ACSS-FAD performed poorly, whereas a four-item version demonstrated satisfactory psychometric properties. INQ-10 did not support the hypothesized two-factor structure, with relatively better support for a bifactor model. The SBQ-R discriminated between students and patients presenting with self-harm (AUC = 0.716, 95% CI = 0.656-0.777), with improved discrimination among patients reporting suicidal intent (AUC = 0.876, 95% CI = 0.820-0.931). The established cut-off of ≥7 was supported.

The Sinhala and Tamil SBQ-R demonstrated good psychometric properties and are suitable for suicide research and risk screening in Sri Lanka. The four-item ACSS-FAD appears preferable to the original version, whereas INQ-10 subscale scores should be interpreted cautiously. These findings support further research on suicidal behavior and evaluation of IPTS-based hypotheses in clinical and community populations in Sri Lanka.