Cost-effectiveness analysis
REGRESSIONS
Estimates of the adjusted mean incremental costs and mean incremental outcomes (QALYs, CORE-OM improvement or WEMWBS improvement) generated from the bivariate regressions are shown in Cost-effectiveness acceptability curves (CEACs) for the base-case and scenario analyses: each curve shows the probability of cost-effectiveness at a particular willingness-to-pay (λ) threshold per unit of outcome (QALYs: base case, S1-3; CORE-OM point: S4; WEMWBS point: S5). CCA, complete case analysis; CORE-OM, Clinical Outcomes in Routine Evaluation Outcome Measure; QALYs, quality adjusted life years; WEMWBS, Warwick-Edinburgh Mental Well-being Scale.UCS costs (£), outcomes (base case and S1–S3: QALYs; S4: CORE-OM unit; S5: WEMWBS unit) and ICER for base case and scenarios, where SAU is the referenceCosts and outcomes adjusted for sex and cohort; additionally, outcomes adjusted by corresponding baseline outcome measurement. CORE-OM scores reversed to align direction of improvement with other outcomes: an increase in CORE-OM here indicates an improvement (reduction) on the original scale.CCA, complete case analysis; CORE-OM, Clinical Outcomes in Routine Evaluation Outcome Measure; ICER, incremental cost-effectiveness ratio; Incre. dif., incremental difference; QALYs, quality adjusted life years; SAU, support as usual; UCS, University Counselling Service; WEMWBS, Warwick-Edinburgh Mental Well-being Scale.In the base case and all scenarios, MSS+SAU achieves significantly (95% CIs exclude zero) higher (better) outcomes, but is also significantly more expensive, than SAU. In this setting, there are no established thresholds for what ICERs would be considered cost-effective. However, at NICE threshold of £20 000 per QALY, used in economic evaluations for the NHS, MSS+SAU would be considered cost-effective for the base case and scenarios S1–3 (where outcomes are measured in terms of QALYs).The uncertainties surrounding cost-effectiveness conclusions are depicted in the cost-effectiveness planes in the Supplementary file. All bootstrap replicates fell in the north-east quadrant for the base case and all scenarios S1–5: this means that when evaluating uncertainty using bootstrap methods, The probability of cost-effectiveness, illustrated by the CEACs (