Impact of whole-body CT screening on the costeffectiveness of CT colonography

Purpose: to analyze the impact of adding computed tomographic (CT) imaging of the chest on the clinical effectiveness and cost-effectiveness of CT colonography to determine whether performing CT colonography and whole-body CT is a more clinically and cost-effective strategy than CT colonography alone when screening average-risk subjects. Materials and methods: a markov model simulated the occurrence of colorectal neoplasia, extracolonic abominal-pelvic malignancy, lung cancer, coronary artery disease (CAD), and abdominal aortic aneurysm (AAA) in a cohort of 100 000 U. S. subjects aged 50 to 100 years. Cost-effectiveness of CT colonography and whole-body CT was compared with that of CT colonography alone; each test was assumed to be repeated every 10 years between ages of 50 and 80 years. Results: Performing CT colonography and whole-body CT was more effective and costly than was CT colonography alone. The addition of chest CT was associated with a 22% increase in efficacy (life-years gained: 14 662 vs 11 990) and with a 48% increase in cost per person ($13 605 vs $9 223). Both strategies were cost effective as compared with no screening, with an incremental cost-effectiveness ratio (ICER) of $17 672 (CT colonography alone) and $44 337 (CT colonography and whole-body CT), respectively, but performing CT colonography and whole-body CT was not a cost-effective option when compared with CT colonography alone (ICER, $164 020). This was mainly a result of the high cost of false-positive follow-up for CAD and to the poor efficacy of lung cancer screening. Expected value of perfect information was $520 per patient. Conclusion: The addition of chest CT to CT colonography does not appear to be a cost-effective alternative. Further research is needed before whole-body CT can be recommended in clinical practice.