Psychometric Outcomes of a Phased Residential Program for Substance Use Disorders: A Retrospective Pre-Post Cohort Service-Evaluation

Residential treatment for substance use disorders (SUDs) is widely used, but outcome evidence remains limited by inconsistent measurement and insufficient attention to multidomain recovery. 158 treatment episodes were analyzed from a 28-day phased residential program in the United Kingdom. Admission and pre-discharge measures included the Patient Health Questionnaire (PHQ-9), Generalized Anxiety Disorder scale (GAD-7), Brief Craving Scale (BCS) and WHOQOL-BREF psychological domain. Change was estimated using Cohen’s dz with 95% confidence intervals. Clinically meaningful change was assessed using reliable change indices and study-defined improvement thresholds. Temporal stability was also examined. Large to very large improvements were observed across all domains: depression (dz = 2.14), anxiety (dz = 1.90), craving (dz = 1.43) and psychological quality of life (dz = 1.46) (all p <.001). Reliable improvement occurred in 61.4%–82.3% of episodes. Study-defined improvement thresholds were met in at least three of four domains in 86.1% of cases, and 57.0% improved across all four domains. Severity distributions shifted markedly toward minimal or mild ranges by discharge, with no evidence of performance drift. A phased residential model was associated with substantial multidomain improvement in routine care, supporting structured treatment sequencing and multidomain outcome assessment in addiction recovery.