A comparison of two methods for expert elicitation in health technology assessments
OBJECTIVE To evaluate the cost-effectiveness of degarelix vs luteinizing hormone-releasing hormone analogue (triptorelin) plus short-term antiandrogen treatment for advanced prostate cancer. METHODS We developed a decision analytic model based on a clinical trial and literature review. The two interventions evaluated were: (i) monthly injection of degarelix and (ii) 3-monthly triptorelin therapy plus short-term flutamide, cyproterone or bicalutamide treatment. The model consisted of a decision tree monitoring a hypothetical cohort of patients aged 70 years from the start of hormonal treatment to the end of the first month, and a Markov model monitoring patients from the end of month 1 for a time horizon of 10 years (i.e. when 96% of patients are assumed to have died). The base-case analysis assumed patients present with asymptomatic metastatic prostate cancer. Costs and outcomes were collected over the model time horizon. Outcome measures were quality-adjusted life years (QALYs), lifetime costs and incremental cost-effectiveness ratios. Sensitivity analyses (one-way and multi-way) and probabilistic sensitivity analyses were conducted to explore the uncertainties around the assumptions. RESULTS In the base-case analysis, the incremental cost-effectiveness ratio (ICER) for degarelix vs triptorelin plus antiandrogen was £59,000 per QALY gained. The model was most sensitive to the rate of significant adverse events in the triptorelin plus antiandrogen group. The model was also sensitive to the assumed survival of patients with metastatic prostate cancer and the price of degarelix. The results of the probabilistic sensitivity analyses suggested that there was a low probability (9.6%) of degarelix being the most cost-effective treatment option when a willingness-to-pay threshold of £30,000 per QALY gained is assumed. CONCLUSION Degarelix is unlikely to be cost-effective compared to triptorelin plus short-term antiandrogen in the management of advanced prostate cancer with respect to the usual thresholds of cost-effectiveness used in the UK: £20,000-30,000 per QALY gained (used by the National Institute for Health and Clinical Excellence).