Supplementary Material for: Development of OSTQOL: A Measure of Quality of Life for Patients in Opioid Substitution Treatment

Background: Quality of life (QOL) of patients in opioid substitution treatment (OST) is increasingly being addressed in research. However, no disease- or treatment-specific instrument is available to assess the QOL of this target population. The purpose of this project was to develop the first QOL instrument for OST patients. Methods: Focus groups with 60 OST patients were analyzed using thematic analysis to elicit key QOL themes as perceived by patients. Identified themes were developed into items and refined through pilot testing and cognitive debriefing. The resulting 82 items were tested in a large sample of OST patients (n = 577). Principal component analysis with varimax rotation was performed to explore a possible factor structure and reduce the number of items. Psychometric properties were assessed. Results: Factor analysis revealed 6 subscales accounting for 46.1% of the variance: Personal Development, Mental Distress, Social Contacts, Material Well-being, Opioid Substitution Treatment, and Discrimination. The 38-item instrument demonstrated good to acceptable internal consistency reliability for all subscales (Cronbach’s alpha = 0.75–0.88), and good convergent and discriminant validity. Conclusion: The Opioid Substitution Treatment Quality of Life scale (OSTQOL) is a multidimensional instrument with low respondent and administrator burden. A thorough validation is needed to assess its validity.