BACKGROUND AND AIMS: Measurement-based care (MBC) is a structured approach using standardized, repeated assessments to monitor treatment progress and guide clinical decision-making. MBC improves outcomes for substance use treatment but can be time consuming due in part to lengthy assessment tools. Single-item, patient-reported outcome measures (PROMs) offer a more acceptable alternative for routine monitoring, yet their psychometric properties have not been systematically evaluated. We sought to identify constructs assessed by single-item PROMs in substance use treatment and critically appraise their validity, reliability and overall quality using standardized criteria.

METHODS: We conducted a systematic review following COSMIN and PRISMA guidelines. MEDLINE, Embase and PsycINFO were searched from January 2005 to August 2025 for studies evaluating single-item PROMs in adults with substance use. We assessed psychometric properties, including content validity, test-retest reliability, construct validity, responsiveness and predictive validity using COSMIN criteria. Quality of evidence was assessed using a modified GRADE approach.

RESULTS: Of 4722 records screened, 35 studies met inclusion criteria, evaluating 68 single-item PROMs across 9 clinical constructs for more than 50 000 participants. Fifteen studies achieved an overall rating of sufficient measure properties and moderate-or-above level of evidence rating across domains. Test-retest reliability ranged approximately from Intraclass Correlation Coefficient = 0.60-0.85; construct validity correlations approximately ranged r = 0.11-0.98. Predictive validity was strong for several measures, with odds ratios up to 7.3 for treatment readiness. Measures assessing craving, treatment readiness and self-efficacy demonstrated the most robust evidence and, in some cases, outperformed multi-item scales. However, over half of measures lacked empirically validated thresholds and responsiveness to change analyses, limiting clinical interpretability and treatment monitoring.

CONCLUSIONS: Single-item patient-reported outcome measures (PROMs) are pragmatic tools for implementing measurement-based care in substance use treatment, offering strong implementation feasibility and, in some cases, predictive performance comparable to longer instruments. PROMs lacking validated thresholds or responsiveness may be best used as complementary tools, whereas those with strong evidence and thresholds can support primary monitoring.