In the base case scenario the incremental cost per QALY gained using omeprazole rather than ranitidine was Can$46,900. In sensitivity analysis the most sensitive parameter was the utility associated with dysphagia and dilation. Varying this between 0.00 and 0.32 (base case 0.068) led to an incremental cost per QALY ranging from Can$1,850,000 and Can$11,800. Varying the probability of redilation whilst on either omeprazole or ranitidine also lead to a wide range of cost utility ratios. In the case of omeprazole varying the baseline estimate of 0.30 between 0.20 and 0.40 led to incremental costs per QALY ranging between Can$30,100 and Can$135,200. Similarly for ranitidine varying the base estimate of 0.46 between 0.40 and 0.60 led to incremental costs per QALY between Can$80,700 and Can$25,800.
Varying the costs of the two drugs also had an impact. For omeprazole varying this between Can$500 and Can$1,862 led to costs per QALY between Can$11,200 and Can$132,000. For ranitidine varying between Can$180 and Can$709 would produce incremental costs per QALY between Can$65,500 and Can$18,300. No other parameters in the analysis varied the baseline scenario significantly.