Objective: To assess the cost effectiveness of the addition of folinic acid to fluorouracil plus levamisole in patients with colon cancer from the perspective of the German Social Health Insurance.
Study design and methods: Patients with International Union Against Cancer (Union International Contre Cancer; UICC) II/T(4) or UICC III colon cancer enrolled in an open-label randomised clinical trial in Germany (Forschungsgruppe Onkologie Gastrointestinaler Tumoren-1 [FOGT-1]) received either fluorouracil plus levamisole (A, standard) or fluorouracil plus levamisole and folinic acid (B) for 12 months as adjuvant chemotherapy after curative intended surgery. Outcome measures for economic evaluation were disease-free life-years gained (df-LYG) and overall life-years gained (LYG) derived from the respective Kaplan-Meier survival curves. Direct medical costs from the perspective of the German Social Health Insurance were estimated retrospectively (2000 values) and incremental cost-effectiveness ratios (ICERs) were calculated. A Markov model was used to project the trial results beyond 5 years for the patients' remaining life expectancy.
Results: Adding folinic acid to the fluorouracil/levamisole regimen results in an increase in time to progression and survival in patients with locally advanced colon cancer. Within the trial period of 5 years ICERs (B versus A) were 33,008 Euro per df-LYG and 51,225 Euro per LYG (costs and effects discounted at 5%). The Markov model yielded ICERs of 11,176 Euro per df-LYG and 11,020 Euro per LYG (costs and effects discounted at 5%). The model was robust for variations of key variables in the sensitivity analysis.
Conclusions: Results of this cost-effectiveness analysis suggest that the addition of folinic acid offers clinical benefits at additional costs which are likely to be acceptable for decision makers in the long term. Cost-effectiveness ratios calculated within the clinical trial period were just above 50,000 Euro/LYG. Because treatment benefits, i.e. prolonged survival, are sustained beyond 5 years whereas incremental costs are mainly incurred in the first year, results of the Markov model yielded cost-effectiveness ratios that compare more favourably with other published ICERs.