The impact of including future medical care costs when estimating the costs attributable to a disease: A colorectal cancer case study

A source of controversy in the economic literature concerns whether to incl ude or exclude future medical care costs when computing attributable costs for lifesaving interventions. Although it is hypothesized that including fu ture medical care costs will offset the cost savings achieved through preve ntion, the magnitude of the effect is not known. The objectives of the present study are to develop a methodology for estima ting the excess costs of care among colorectal cancer patients, including a nd excluding future costs of care, and comparing these results with previou s studies that do not include costs in added years of life. Subjects in the study included those identified with colorectal cancer draw n from the Surveillance, Epidemiology and End Results (SEER)-Medicare datab ase and an age- and gender-matched control group drawn from the general Med icare population. Using the Kaplan-Meier Sample Average estimator, we direc tly estimate expected 11-year costs, and then, with the addition of some si mple extrapolating assumptions, determine expected 25-year costs. The latte r time horizon captures lifetime costs for over 90% of the cohort. Males results for discounted, stage-specific 11- versus 25-year excess cost s: in situ, $22411 versus $23494; Stage 1, $29365 versus $32510; Stage 2, $ 28114 versus $25263; Stage 3, $27397 versus $19647; Stage 4, $3006 versus $ 7837. Trends were similar for females. It can be concluded that adding costs of care in future years for those who se colorectal cancer is prevented owing to screening greatly alters the est imate of lifetime excess costs for colorectal cancer patients, and can prod uce negative results for advanced stage disease. The results emphasize the need to adopt a standard approach for dealing with future costs when evalua ting lifesaving interventions for cost-effectiveness analyses. Copyright (C ) 2001 John Wiley & Sons, Ltd.