Validation and Analysis of the Psychometric Properties of Two Irritability-Measuring Tools: The Affective Reactivity Index (ARI) and the Born-Steiner Irritability Scale (BSIS) in the Italian Adult and Adolescent Populations

Irritability is a transdiagnostic symptom that affects quality of life during the lifespan of individuals. The objective of the present research was to validate two assessment tools, namely the Affective Reactivity Index (ARI) and the Born-Steiner Irritability Scale (BSIS). We investigated internal consistency as measured with Cronbach’s alpha, test–retest with intraclass correlation coefficient (ICC) and convergent validity confronting ARI and BSIS scores with the strength and difficulties questionnaire (SDQ). Our results revealed ARI good internal consistency with a Cronbach’s α of 0.79 for adolescent and 0.78 for adults. The BSIS also demonstrated good internal consistency for both samples with Cronbach’s α = 0.87. Test–retest analysis showed excellent values for both tools. Convergent validity showed positive and significant correlation with SDW, albeit weak for some sub-scales. In conclusion, we found ARI and BSIS to be good tools for measuring irritability in adolescents and adults, and now, Italian healthcare professionals can use it with more confidence.