Colon Cancer Treatment Costs for Medicare and Dually Eligible Beneficiaries

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INTRODUCTION

The cost of colorectal cancer has recently been the subject of several scientific investigations (Wright et al., 2007; Yabroff et al., 2007a; Warren et al., 2008). These investigations were most likely spurred by recent screening initiatives and efforts to raise public awareness of colorectal cancer. Accurately estimating the direct medical cost of cancer is relevant to policymakers weighing new options for cancer prevention and control, screening guidelines, and treatments. A descriptive review of cancer cost studies found significant heterogeneity in estimation methods, study settings, populations, and measurements of cost (Yabroff et al., 2007b). Past analyses of the cost of cancer treatment focused on long-term aggregate estimates (Brown et al., 1999; 2002; Etzioni et al., 2002) and were not designed to answer questions related to patient characteristics or treatment regimens.

In this study, we have two objectives: (1) to extend prior studies by estimating the cost attributable to colon cancer 1-year after diagnosis by cancer stage, comorbidity, treatment regimen, and other patient characteristics; and (2) to estimate the differences in 1-year cost between Medicare only and the dually eligible beneficiaries. Colon cancer usually occurs later in life (at age 60 to 70 years), and Medicare and Medicaid are the primary payers of cancer care. We focused on colon cancer instead of colorectal cancer because the cost of rectum cancer is usually higher and because colon cancer is among the cancer sites where screening, early detection, and effective treatment are feasible and proven to reduce mortality (Midgley and Kerr, 2005). Individuals who receive health care coverage from the Medicare and Medicaid Programs for at least 12 months prior to the diagnosis of cancer are defined as dual eligibles in this and our previous study (Bradley, Luo, and Given, 2008). Dually eligible beneficiaries are more likely to live under the Federal poverty level, reside in nursing homes or live alone, be from a minority population and unmarried, and have lower education attainment (Murray and Shatto, 1998). Studies have found that Medicaid patients are less likely to receive cancer screening and more likely to be diagnosed at a later cancer stage than are Medicare only patients (Ward et al., 2008). An inquiry on cancer cost differentials by cancer stage, treatment procedure and comorbidity between Medicare only and dually eligible groups can shed light on disparity in healthcare utilization. Our method of estimating 1-year cost takes into account prior year non-cancer costs and treatment received.

DATA AND METHODS

Cancer Patients

We used statewide Medicaid and Medicare data merged with the Michigan Tumor Registry to extract a study sample of patients with a first primary colon cancer diagnosis in the years 1997 through 1999. The Michigan Cancer Surveillance Program, which maintains the Michigan Tumor Registry, is more than 95% complete based on external audit findings. For details of the linkage process, see Bradley et al. (2007). This study was approved by Institutional Review Boards at the Michigan Department of Community Health, Michigan State University, and Virginia Commonwealth University.

From statewide Medicare files, we extracted all claims for inpatient, outpatient, physician services, and hospice during the study period for all patients who correctly matched to the Michigan State segment of the Medicare Denominator file (approximately 89% of patients) and were enrolled in Parts A and B. Patients enrolled in Part A only were excluded for lack of physician office visit information.

We identified 8,157 Medicare Parts A and B beneficiaries aged 66 years and older who had a first primary colon cancer diagnosis from 1997 to 1999. Our database contains claims from January 1996 to December 2000 so that all patients had at least 12 months of data before and after the month of diagnosis. …