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/alcohol users in residential treatment, a review of validated sleep measures, focus groups with drug/alcohol users in residential treatment, and feedback from drug/alcohol users recruited from community and residential settings. An initial version of the measure was completed by 549 current and former drug/alcohol users (442 in person [IP] and 107 online [OL]). 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 7 items were removed due to low item-factor loadings, 2 factors were retained and labelled: ‘Mind and Body Sleep Problems’ (14 items) and ‘Substance Related Sleep Problems’ (9 items). Measurement invariance was confirmed with respect to gender, age, and administration format. IRT (information) and classical test theory (internal consistency, stability) indicated measure reliability. Standard parametric and non-parametric techniques supported convergent and discriminant validity. Conclusions: SUSS is an easy-to-complete patient reported outcome measure of sleep for people with drug/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.