The main objective of the study is to provide new knowledge about the implementation of DBT-informed environmental therapy in short-term substance use disorder (SUD) inpatient treatment. The study will examine which organizational and clinical conditions promote or inhibit implementation in clinical practice by elucidating how the implementation is experienced by staff (including experiences with structure, skill focus and environmental therapeutic principles) related to DBT-informed environmental therapy, DBT-SUD skill groups and patients' perceived satisfaction and utility.

A secondary and exploratory aim is to examine preliminary trends in clinical measures in patients over time, including changes in symptom burden and reported use of DBT skills throughout the course of treatment. The study further seeks, at a descriptive and hypothesis-generating level, to explore patterns in patient-reported conditions related to substance abuse, emotion regulation, and other clinical burden. The sample will consist of up to 70 adult patients and 12 staff. One half of the patients will receive ordinary short-term inpatient treatment, while the other half will receive DBT informs milieu therapy after the approach has been established in clinical practice without being implemented. All patients will complete questionnaires upon admission (baseline), week 6 and upon discharge (week 12).

This pilot implementation study evaluates the introduction of DBT-informed milieu therapy in a short-term inpatient substance use disorder (SUD) treatment unit. The study aims to investigate the feasibility, acceptability, and fidelity of implementing DBT-informed milieu therapy in routine clinical practice, as well as to explore preliminary trends in patient-reported clinical outcomes.

The study uses a sequential A-B design. During Phase A, patients receive treatment as usual (TAU), consisting of standard short-term inpatient SUD treatment. During Phase B, DBT-informed milieu therapy is implemented as part of routine care following staff training and integration of DBT-informed principles and skills into daily clinical practice.

Implementation outcomes are assessed at the unit level and include measures of fidelity, feasibility, acceptability, and adherence to planned implementation activities. Data sources include implementation records, staff questionnaires, and qualitative interviews with staff members involved in the implementation process.

Patient-reported clinical outcomes are collected to explore changes during treatment and to generate hypotheses for future studies. Outcomes include emotion regulation, borderline symptom severity, DBT-related coping skills, alcohol use, and drug use. Data are collected at admission (baseline), week 6, and discharge when applicable.

The study is conducted in a multidisciplinary specialized substance use disorder treatment service. Adult patients admitted to the participating short-term inpatient unit are recruited consecutively during the study period. The study is intended to provide knowledge about factors that facilitate or hinder implementation of DBT-informed milieu therapy and to inform future larger-scale evaluations.

Inclusion Criteria

Adults aged 18 years or older. Admitted to the participating short-term inpatient substance use disorder treatment unit during the study period.

Able and willing to provide written informed consent.

Exclusion Criteria

Unable to understand study information. Unable to provide informed consent. Severe cognitive impairment or other conditions preventing meaningful participation in study procedures.

It has not yet been determined whether de-identified individual participant data will be made available. Any future data sharing will be subject to applicable ethical approvals, institutional policies, data protection regulations, and participant consent.