Cost-effectiveness analysis of depression case finding followed by alerting patients and their GPs among older adults in northern England: results from a regression discontinuity study.

Background: In the UK, around 1 in 4 adults over 65 years suffers from depression. Depression case finding followed by alerting patients and their general practioners (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 with standard of care (SoC) in northern England.

Method: Conducted alongside the CASCADE study, 1020 adults aged 65+ years were recruited. Participants with baseline Geriatric Depression Scale (GDS) ≥5 were allocated to the intervention arm and those >5 to SoC. Resource use and EQ-5D-5L data were collected at baseline and 6 months. Incremental cost-effectiveness ratio was calculated. Non-parametric bootstrapping was performed to capture sampling uncertainty. The results are presented using cost-effectiveness acceptability curves. 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 quality-adjusted life years than SoC; the probability of the former being cost-effective was <5% at a £30 000 cost-effectiveness threshold. Sensitivity analyses confirmed the base-case findings. Subgroup analyses indicated that screening + GP was cost-effective when patients with baseline GDS 2-7, 3-6 and 4-5, respectively, were analysed.

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.