Cost effectiveness of imiquimod 5% cream compared with methyl aminolevulinate-based photodynamic therapy in the treatment of non-hyperkeratotic, non-hypertrophic actinic (solar) keratoses: a decision tree model.

BACKGROUND: Actinic keratosis (AK) is caused by chronic exposure to UV radiation (sunlight). First-line treatments are cryosurgery, topical 5-fluorouracil (5-FU) and topical diclofenac. Where these are contraindicated or less appropriate, alternatives are imiquimod and photodynamic therapy (PDT). OBJECTIVE: To compare the cost effectiveness of imiquimod and methyl aminolevulinate-based PDT (MAL-PDT) from the perspective of the UK NHS. METHODS: A decision tree model was populated with data from a literature review and used to estimate costs and QALYs gained and incremental cost effectiveness over 1 year. The model simulated patients who were in secondary care, who had four to nine AK lesions, and for whom cryosurgery, 5-FU and diclofenac were contraindicated or considered less appropriate. RESULTS: Over 1 year, imiquimod cost £174 less than MAL-PDT (year 2006 values) but resulted in 0.005 fewer QALYs gained. The incremental cost-effectiveness ratio (ICER) of MAL-PDT over imiquimod was £34,576. In the probabilistic sensitivity analysis, there was a 75% probability that imiquimod was cost effective compared with MAL-PDT at a threshold of £20,000 per QALY gained, falling to 73% at £30,000. CONCLUSIONS: Imiquimod may be the more cost-effective treatment at conventional cost-effectiveness thresholds. A direct head-to-head study of MAL-PDT versus imiquimod is required to reduce uncertainty.