Development and early validation of a patient-reported outcome measure to assess sleep amongst people experiencing problems with alcohol or other drugs

Study Objectives: To develop a patient-reported outcome measure to assess sleep amongst people experiencing problems with alcohol or other drugs. Methods: Item development included secondary analyses of qualitative interviews with drug or alcohol users in residential treatment, a review of validated sleep measures, focus groups with drug or alcohol users in residential treatment, and feedback from drug or alcohol users recruited from community and residential settings. An initial version of the measure was completed by 549 current and former drug or alcohol users (442 in person and 107 online). Analyses comprised classical test theory methods, exploratory and confirmatory factor analysis, measurement invariance assessment, and item response theory (IRT). Results: The initial measure (30 items) had good content and face validity and was named the Substance Use Sleep Scale (SUSS) by addiction service users. After seven items were removed due to low item-factor loadings, two factors were retained and labeled: "Mind and Body Sleep Problems" (14 items) and "Substance-Related Sleep Problems" (nine items). Measurement invariance was confirmed with respect to gender, age, and administration format. IRT (information) and classical test theory (internal consistency and stability) indicated measure reliability. Standard parametric and nonparametric techniques supported convergent and discriminant validity. Conclusions: SUSS is an easy-to-complete patient-reported outcome measure of sleep for people with drug or alcohol problems. It can be used by those concerned about their own sleep, and by treatment providers and researchers seeking to better understand, assess, and potentially treat sleep difficulties amongst this population. Further validity testing with larger and more diverse samples is now required.