Does the Revised Child Anxiety and Depression Scale (RCADS) measure anxiety symptoms consistently across adolescence? The TRAILS study.

We assessed if the Revised Child Anxiety and Depression Scale (RCADS) measures anxiety symptoms similarly across age groups within adolescence. This is crucial for valid comparison of anxiety levels between different age groups. Anxiety symptoms were assessed biennially in a representative population sample (n = 2226) at three time points (age range 10-17 years) using the RCADS anxiety subscales (generalized anxiety disorder [GAD], obsessive-compulsive disorder [OCD], panic disorder [PD], separation anxiety [SA], social phobia [SP]). We examined longitudinal measurement invariance of the RCADS, using longitudinal confirmatory factor analysis, by examining the factor structure (configural invariance), factor loadings (metric invariance) and thresholds (strong invariance). We found that all anxiety subtypes were configural invariant. Metric invariance held for items on the GAD, OCD, PD and SA subscales; yet, for the SP subscale three items showed modest longitudinal variation at age 10-12. Model fit decreased modestly when enforcing additional constraints across time; however, model fit for these models was still adequate to excellent. We conclude that the RCADS measures anxiety symptoms similarly across time in a general population sample of adolescents; hence, measured changes in anxiety symptoms very likely reflect true changes in anxiety levels. We consider the instrument suitable to assess anxiety levels across adolescence.