Linking the Perceived Stress Scale to the PROMIS Psychological Stress Experiences-Pediatric in adolescents

The Perceived Stress Scale (PSS) and PROMIS Psychological Stress Experiences-Pediatric (PPSE) are two self-report instruments that have been used with adolescents to measure subjective feelings of stress. Stress is a critical construct to evaluate, as chronic stress can result in negative long-term consequences for an individual's physical and mental health. While the PSS is more commonly used in research and clinical practice, use of the PPSE is becoming more widespread. This increased usage necessitates a way to compare the measures, for example, when changing which instrument is used in practice or when combining data from the two measures in pooled analysis. After assessing linking assumptions, we used equipercentile linking to score-link the two measures on the raw score and T-score metrics for both longer forms (10 PSS items; 8 PPSE items) and shorter forms (4 PSS or PPSE items), yielding crosswalk tables (Open Science Framework: https://osf.io/9pzyk/) to convert scores on each measure to the metric of the other. Raw scores between measures (.670 = r = .794) were not sufficiently correlated for score linking. Therefore, linked scores were treated as predictions, rather than counterfactual values on the alternative measure. Further, confirmatory factor analyses revealed that this low correlation was primarily due to the low reliability and multidimensionality of the PSS, and the derived linking functions were found to have minimal bias. Recommendations for the use of these conversion tables by researchers and practitioners are provided.