Expected costs and QALYs for age-variant screening scenarios were €1,074 and 10.961 with no screening, €1,107 and 10.968 with gFOBT at 55 to 74 years, €1,092 and 10.966 with gFOBT at 55 to 64 years, €1,089 and 10.963 with gFOBT at 65 to 74 years, €1,114 and 10.984 with faecal immunochemical testing at 55 to 74 years, €1,094 and 10.978 with faecal immunochemical testing at 55 to 64 years, €1,088 and 10.969 with faecal immunochemical testing at 65 to 74 years, €1,077 and 10.966 with flexible sigmoidoscopy once at 60 years and €1,092 and 10.968 with flexible sigmoidoscopy once at 55 years.
For base case strategies compared with no screening, the lowest incremental cost per QALY gained was €589 with flexible sigmoidoscopy followed by faecal immunochemical testing at €1,696 and gFOBT at €4,428; gFOBT was eliminated by extended dominance. The incremental cost per QALY with faecal immunochemical testing over flexible sigmoidoscopy was €2,058. All these ratios appeared well below the notional cost-effectiveness threshold of €45,000 per QALY.
The most influential inputs were discount rate, cost of screening tests and costs of managing colorectal cancer. The results of the probabilistic sensitivity analysis showed that there was a great uncertainty on the most cost-effective approach.