Ciclosporin compared with 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 randomized controlled trial (RCT). OBJECTIVES To compare the cost-effectiveness of ciclosporin and prednisolone-initiated treatment for patients with PG. METHODS Quality of life (QoL, EuroQoL five dimensions three level questionnaire, 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 quality-adjusted life years (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% confidence interval (CI) -2991 to 672] and improvement in QoL (net QALYs: 0·055; 95% CI 0·018-0·093). However, this finding appears driven by a minority of patients with large lesions (≥ 20 cm2 ) (net cost: -£5310; 95% CI -9729 to -891; net QALYs: 0·077; 95% CI 0·004-0·151). 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 National Health Service resources. However, ciclosporin-initiated treatment may be more cost-effective for patients with large lesions.