Ciclosporin compared to prednisolone therapy for patients with pyoderma gangrenosum: cost-effectiveness analysis of the STOP GAP trial

Background Pyoderma gangrenosum (PG) is a painful, ulcerating skin disease with poor evidence for management. Prednisolone and ciclosporin are the most commonly used treatments, although not previously compared within a randomised controlled trial (RCT) Objectives To compare the cost-effectiveness of ciclosporin and prednisolone-initiated treatment for patients with PG. Methods Quality-of-life (EuroQoL EQ-5D-3L) and resource data were collected as part of the STOP-GAP trial: a multicentre, parallel-group, observer-blind RCT. Within-trial analysis used bivariate regression of costs and QALYs, with multiple imputation of missing data, informing a probabilistic assessment of incremental treatment cost-effectiveness from a health service perspective. Results In the base case analysis, when compared with prednisolone, ciclosporin was cost-effective due to a reduction in costs (net cost: -£1160; 95%CI: (-2991 to 672) and improvement in quality of life (net QALYs: 0.055; 95%CI: 0.018 to 0.093). However, this finding appears driven by a minority of patients with large lesions (≥20cm2) (net cost: -£5310; 95%CI: -9729 to -891; net QALYs: 0.077; 95%CI: 0.004 to 0.151). The incremental cost-effectiveness of ciclosporin for the majority of patients with smaller lesions was £23,374/QALY although the estimate is imprecise: the probability of being cost-effective at a willingness to pay of £20,000/QALY was 43%. Conclusions Consistent with the clinical findings of the STOP-GAP trial, patients with small lesions should receive treatment guided by the side effect profiles of the drugs and patient preference - neither strategy is clearly a preferred use of NHS resources. However, ciclosporin-initiated treatment may be more cost-effective for patients with large lesions