Comparison of Approaches for Estimating Prevalence Costs of Care for Cancer Patients What Is the Impact of Data Source?

Background: National prevalence costs of medical care can be key inputs in health policy decisions. Cost estimates vary across data sources, patient populations, and methods, however, the objective of this study was to compare 3 approaches for estimating the prevalence costs of colorectal cancer (CRC) care using different data sources, but similar patient populations and methods. Methods: We identified prevalent CRC patients aged 65 and older from: (1) linked Surveillance Epidemiology and End Results (SEER) registry-Medicare data, (2) Medicare claims only, and (3) the Medical Expenditure Panel Survey (MEPS). Controls were matched by sex, age-group, and geographic location. Mean per person total and net costs, measured as the difference between patients and controls, were compared for each approach during a similar observation period. The SEER-Medicare approach was our reference, and we evaluated the impact of patient selection criteria with sensitivity analyses. Aggregate prevalence estimates were also compared. Results: We found considerable variability across the different approaches to estimating prevalence costs of CRC. Mean net annual per person estimates in the SEER-Medicare reference were $5341 (95% CI: $5243, $5439), compared with $8736 (95% CI: $8203, $9269) for the Medicare claims only and $11,614 (95% CI: $7566, $15,663) for the MEPS. Aggregate national estimates of net prevalence costs of CRC in 2004 ranged from $4524 million, using the SEER-Medicare approach, to $9629 million, using the MEPS approach. Estimates varied by data source based on the payors included and identification of prevalent CRC patients. Conclusions: CRC prevalence cost estimates vary substantially depending on the data sources. Our findings have implications for estimating prevalence costs for other cancers and other diseases without registry systems that can be used to identify newly diagnosed individuals as well as those diagnosed less recently.