(PS7-D76) Bursting the SUDS Bubble: Refining the Psychometrics of the Subjective Units of Distress Scale with Ecological Momentary Assessment

Background: The Subjective Units of Distress Scale (SUDS) is a self-report measure of anxiety and distress (Wolpe & Lazarus, 1966) used across clinics and research settings. In clinical-research practice, it is often used during exposure and response prevention (ERP) to monitor patient progress, prevent exposures from becoming too distressing too quickly, and test the efficacy of interventions (Abramowitz et al., 2019; Wolpe, 1961). However, the psychometric properties of the SUDS have never been reviewed within a structured theoretical framework for construct validation. Moreover, studies that have examined the psychometrics of the SUDS are flawed, as they (a) focus on atheoretical (vs. theoretical) correlations between the SUDS and other measures and (b) fail to evaluate the SUDS as a moment-to-moment measure of anxiety and distress. Using the Strong Program of Construct Validation, we evaluate the psychometrics of the SUDS as a measure of changing emotional valence, consistent with an Ecological Momentary Assessment (EMA) perspective. We then propose improvements to the SUDS relevant to clinical and research practice.

Method: To evaluate the psychometric properties of the SUDS, we examined it within the framework of the Strong Program of construct validation (Benson, 2005; Loevinger, 1957). This framework of construct validation has been used extensively for several decades, recommended in modern factor analytic texts (Watkins, 2021) and included in recent investigations validating moment-to-moment changes in emotional constructs (Cloos et al., 2022). We critically examined the SUDS within the Strong Program’s substantive, structural, and external stages. Concurrently, we compared the SUDS to validated measures of distress, as proposed by Cloos and colleagues (2023), that capture within person variance over time to understand how the SUDS fits within contemporary measurement theory and practice.

Results: Evaluation in the Strong Program reveals that the SUDS has weak psychometric properties. Specifically, it suffers from construct underrepresentation, construct irrelevance, and modern definitional problems.

Conclusion: When assessing affective experiences, like distress, it is essential to capture moment-to-moment, within-person variability (Brose et al., 2020). The SUDS seeks to measure this kind of variability, but studies are lacking that establish its psychometric properties as either a state or trait measure. Use of the single-item measures developed by Cloos and colleagues (2023) in EMA format, we may be able to measure “distress” in a way that is psychometrically valid—an important contribution to the field of cognitive-behavioral therapy and practice.