Published literature lacks consensus, and most guidelines lack definitive recommendations as to whether cost-effectiveness analyses (CEAs) should include all "future" costs or distinguish between related and unrelated medical costs. This systematic review of oncology CEAs evaluated cost methods used and the impact on the cost-effectiveness of incorporating different cost categories, including costs due to study intervention, related medical costs of the treated condition, and unrelated medical costs. Of the 59 studies reviewed, none included medical costs unrelated to the treated condition and 14 studies (32%) excluded direct medical costs related to the condition but not the evaluated intervention. Recomputing ICERs using different cost categories altered overall cost-effectiveness conclusions. The authors propose conventional CEA methods may implicitly penalize therapies that add "expensive" life years for chronically ill patients. Presenting ICERs computed with and without disease-attributable costs can help better convey how much the treatment itself contributes to overall costs.
Keywords: cost methodology; cost-effectiveness analysis; future costs; oncology.