Cost-effectiveness analysis of top-down versus step-up strategies in patients with newly diagnosed active luminal Crohn's disease

BACKGROUND: Top-down (TD) strategy with frontline infliximab proved to be more effective than the traditional step-up (SU) approach in newly diagnosed luminal moderate-to-severe CD patients. However, the considerable cost of infliximab calls its universal use as frontline treatment into question. The aim of this study is to evaluate the cost-effectiveness of the TD approach using a Markov decision model. METHODS: Four states were modelled, namely step 1, step 2, step 3 and death. The first three steps were in TD infliximab induction plus azathioprine, infliximab rechallenge plus azathioprine and steroids plus azathioprine, and in SU steroid induction, azathioprine plus steroid rechallenge and infliximab plus azathioprine. Each health state lasted 1 month. The time horizon of the model was 5 years. Transition probabilities and quality of life were estimated from a randomised trial. First- and second-order sensitivity analyses were done to test the robustness of the results. RESULTS: At baseline analysis, TD improved quality-adjusted life expectancy from 3.76 to 3.90 quality-adjusted life years (QALYs), that is, 0.14 QALYs, while allowing a saving of <euro>773, proving dominant when compared to SU. TD was cost-saving in 66 \% of the Monte Carlo simulations and cost <euro>20,000/QALY in 84 \%. At sensitivity analysis the most significant variables were infliximab cost and time horizon: doubling infliximab cost (<euro>1,000 per 100 mg vial) resulted in an incremental cost-utility ratio of <euro>12,114/QALY. CONCLUSIONS: TD is a cost-effective treatment in newly diagnosed CD patients with luminal moderate-to-severe disease, and sensitivity analysis showed the result to be robust.