Inventory of Callous-Unemotional Traits (ICU) Factor Structure and Measurement Invariance in an Adolescent Multinational Sample

OBJECTIVE: The Inventory of Callous-Unemotional Traits (ICU) is a widely used, comprehensive measure of callous-unemotional (CU) traits. While the ICU total score is used frequently in research, the scale's factor structure remains highly debated. Inconsistencies in past factor structure research appear to be largely due to the use of small non-representative samples and failure to control for method variance (i.e., item wording direction). METHOD: The current study used a multitrait-multimethod (MTMM) confirmatory factor analysis (CFA) approach that considers both trait and method variance to test the factor structure of a 22-item version of the self-report ICU in a multinational community sample of 4,683 adolescents (ages 11-17). RESULTS: Results showed that a hierarchical four-factor model (i.e., one overarching CU factor, four latent trait factors) that controlled for method variance (i.e., by allowing residuals from positively worded items to covary) provided the best fit (χ2 = 2797.307, df = 160, RMSEA=.059, CFI=.922, TLI=.888, SRMR=.045). CONCLUSIONS: After controlling for method variance, the best-fitting factor structure is consistent with how the ICU was developed and corresponds to the four symptoms of Limited Prosocial Emotions (LPE) specifier in the DSM-5 criteria for Conduct Disorder (CD). In addition, measurement invariance of this factor structure across age (i.e., younger versus older adolescents) and sex was supported. As a result, mean differences in ICU total score across age and sex can be interpreted as reflecting true variations in these traits. Further, we documented that boys generally scored higher than girls on the ICU, and this sex difference was larger in later adolescence.