Supplementary Material for: Psychometric Evaluation of the Dutch version of the Substance Use Recovery Evaluator (SURE-NL)

Introduction
Patient-Reported Outcome Measures (PROMs) are an important source of information that allow for a patient-centered assessment. Outcome measurement of substance use disorder (SUD) treatment traditionally focuses on drug use and deficits in functioning, overlooking other aspects of the personal and dynamic process of recovery. The Substance Use Recovery Evaluator (SURE) is a PROM developed with service user input to monitor the recovery journey and assess treatment outcomes in people with SUD.
The objective of this study was to examine the validity and reliability of the Dutch translation of the SURE, the SURE-NL, for measuring indicators of recovery in Dutch-speaking patients with SUD.

Methods
The original SURE questionnaire was translated from English to Dutch using forward-backward translation. A total of N=171 participants were recruited as part of a naturalistic multicenter study in inpatient (N=149) and outpatient (N=22) SUD treatment centers. We examined the factorial structure, reliability, and concurrent and discriminant validity of the SURE-NL.

Results
The original 5-factor structure of the SURE showed acceptable fit for the SURE-NL, and internal consistencies of the subscales ranged from .61 to .76 and internal consistency of the total score was .83. Concurrent validity was confirmed through positive correlations of the SURE-NL total and subscale scores with the WHOQoL-BREF subscales, but correlations varied depending on subscale and treatment setting, with higher correlations for the outpatient compared to the inpatient subgroup. Discriminant validity was confirmed through low, mostly non-significant correlations between the SURE-NL and the DASS-21.

Conclusions
Although the SURE was originally designed for outpatient settings, our findings in a predominantly inpatient sample indicate that the SURE-NL is suitable for assessing personal recovery and recovery capital in Dutch-speaking Belgian patients with SUD. However, subscales should be used and interpreted with caution. Further research is needed with larger Dutch-speaking outpatient samples and the development of a tailored SURE for inpatient settings should be considered.