Malcolm, RobertMedland, SarahTelfer-Thomas, EllenAlshammari, Manar2026-02-152025https://hdl.handle.net/20.500.14154/78192Abstract Background: Opioid use disorder (OUD) is an escalating public health and policy challenge in the UK. While opioids remain essential for acute and palliative pain, long-term prescribing increased sharply, thereby contributing to dependence, overdose, and an increase in mortality. Despite these harms, systematic screening for OUD is not part of routine National Health Service (NHS) primary care. It is therefore important to identify effective and cost-effectiveness screening strategies Methods: This study combined a pragmatic review of the literature with a decision-analytic model to evaluate the cost-effectiveness of introducing the Drug Abuse Screening Test (DAST10) in NHS primary care. Evidence used to populate the model was extracted from published literature and authoritative national data sources , including NICE guidance , the British National Formulary ( BNF) , the NHS Reference cost and the electronic Market information Tool (eMIT) .These sources data on epidemiology provide screening accuracy, treatment effectiveness, health-related quality of life, and costs relevant to opioids used disorder withing the UK context . The analysis was conducted from the perspective of the NHS and personal social services (PSS) over a 12-month time horizon, with the results expressed in terms of cost, quality-adjusted life years (QALYs), and incremental cost-effectiveness ratios (ICERs).A deterministic Sensitivity analyses were performed to test the robustness of the findings. Results: Systematic screening using the DAST-10 was found to be both less costly and more effective than usual care. The expected average cost per patient was £349.18 with screening, compared with £446.69 under usual care. Health outcomes were also better in the screening arm, with an average of 0.8946 QALYs per patient, compared to 0.8703 QALYs for usual care representing a gain of 0.024 QALYs. Because screening achieved greater health benefits at lower cost, the incremental cost-effectiveness ratio (ICER) was negative, indicating dominance. Net monetary benefit (NMB) analysis confirmed that screening remained the economically preferred option across all willingness-to-pay thresholds tested, from £20,000 to £70,000 per QALY, including the Treasury Green Book’s societal valuation of health gains. Conclusion: This analysis suggests that implementing DAST-10 screening in UK primary care could improve health outcomes for people with OUD while also reducing overall NHS costs. The findings suggest that screening is a cost-effective intervention when considered against NICEs threshold for decision making. The model did not capture wider societal costs (e.g., criminal justice, productivity losses) or the long-term downstream effects of untreated OUD, thereby meaning that the benefits of screening may be underestimated. Future research should explore these elements and test sensitivity to key assumptions, including treatment uptake and retention58enOUDOpioid use disorderNHSHealth EconomicsDecision tree modelCost-EffectivnessDAST-10incremental cost-effectiveness ratios (ICERs).QALYsincremental cost-effectiveness ratios (ICERs)primary careaddictionNational Health Servicedecision-analytic modelThesis