Measurement invariance, sex differences, and convergent validity of the Farsi version of the Interpersonal Needs Questionnaire-15 and Acquired Capability with Rehearsal for Suicide Scale-7

Introduction: Suicidality is prevalent in Iran; however, psychometric properties of the scales assessing suicide-related risk factors (i.e., interpersonal needs and capability for suicide) are unavailable in Iran. Thus, this study examined the factor structure, measurement invariance, and convergent validity of the Farsi versions of the Interpersonal Needs Questionnaire (F-INQ) and the Acquired Capability with Rehearsal for Suicide Scale (F-ACWRSS). Methods: Participants were community members (n = 773; 69.1% women) who filled out the F-INQ and F-ACWRSS, as well as scales assessing suicide ideation, suicide attempts, and hopelessness. Analyses focused on validating the factor structure, internal consistencies, convergent validity, and testing measurement invariance of the F-INQ and F-ACWRSS by sex assigned at birth. Results: The original two-factor structure of the F-INQ and a three-factor structure of the F-ACWRSS were supported. Additionally, both the F-INQ and F-ACWRSS were invariant across sex, indicating that the scales perform similarly by sex. Men reported a higher score than women on the pain tolerance subscale of the F-ACWRSS. Both the F-INQ and F-ACWRSS subscales were associated with suicide ideation, suicide attempts, and hopelessness, supporting the convergent validity of the scales. Discussion: Findings suggest that the F-INQ and F-ACWRSS can aid researchers examining suicide-related risk factors in Iran.