Cost-effectiveness Analysis of Depression Case Finding Followed by Alerting Patients and Their General Practitioners among Older Adults in Northern England:Results From a Regression-discontinuity Study

Background In the United Kingdom (UK), around one in four adults over 65 years suffers from depression. Depression case finding followed by alerting patients and their GPs (screening + GP) is a promising strategy to facilitate depression management, but its cost-effectiveness remains unclear. Aims To investigate the cost-effectiveness of screening + GP compared to standard of care (SoC) in Northern England. Method Conducted alongside the CASCADE study, 1,020 adults aged 65+ were recruited. Participants with baseline Geriatric Depression Scale (GDS) ≥ 5 were allocated to the intervention arm and those less than 5 to SoC. Resource use and EQ-5D-5L data were collected at baseline and six-month. Incremental cost-effectiveness ratio was calculated. Non-parametric bootstrapping was performed to capture sampling uncertainty. The results were presented on cost-effectiveness acceptability curves (CEACs). Sensitivity analyses were conducted to assess the robustness of primary findings. Subgroup analyses were undertaken to examine the cost-effectiveness among participants with more comparable baseline characteristics across treatment groups. Results Screening + GP incurred £37 more costs and 0.006 fewer QALYs than SoC. The probability of its being cost-effective was below 5% at £30,000 cost-effectiveness threshold. Sensitivity analyses confirmed the base-case findings. Subgroup analyses indicated screening + GP was cost-effective when patients with baseline GDS 2-7, 3-6, and 4-5 were analysed, respectively. Conclusions Screening + GP was dominated by SoC in Northern England. However, subgroup analyses suggested it could be cost-effective if patients with more balanced baseline characteristics were analysed. Economic evaluations alongside randomised controlled trials are warranted to validate these findings.