Linking the RCADS-25 to the PROMIS^® pediatric item banks Anxiety and Depressive Symptoms in a general Dutch population sample

Purpose: This study aims to link scores of the Revised Child Anxiety and Depression Scale short version (RCADS-25) to the metric of the PROMIS pediatric item banks Anxiety and Depressive Symptoms in a general Dutch population sample. Methods: The RCADS-25 and PROMIS pediatric item banks Anxiety and Depressive Symptoms were administered online to 2,893 Dutch children and adolescents aged 8–18. Assumptions for linking methods were checked. Linking was achieved by using three item response theory (IRT) and two equipercentile methods. For each method, the observed PROMIS metric scores were compared to the ones predicted from the RCADS-25 subscale scores using correlations, mean and SD of differences, and RMSD. Results: The assumptions for IRT-based and equipercentile linking were met. The IRT-based method using separate calibration with Stocking-Lord constants was considered the optimal choice for linking both RCADS-25 subscales to the PROMIS metric. Based on this Stocking-Lord approach, we created item parameters for RCADS-25 items and two crosswalk tables. Conclusion: The RCADS-25 item parameters and crosswalk tables presented in this study are sufficiently valid. Researchers can use these products to translate the RCADS-25 anxiety and depression subscales scores to the PROMIS metric in order to ensure comparability with the previous research.