Longitudinal versus Cross-Sectional Methodology for Estimating the Economic Burden of Breast Cancer
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Background: Projecting future breast cancer treatment expenditure is critical for budgeting purposes, medical decision making and the allocation of resources in order to maximise the overall impact on health-related outcomes of care. Currently, both longitudinal and cross-sectional methodologies are used to project the economic burden of cancer. This pilot study examined the differences in estimates that were obtained using these two methods, focusing on Maryland, US Medicaid reimbursement data for chemotherapy and prescription drugs for the years 1999–2000.
Methods: Two different methodologies for projecting life cycles of cancer expenditure were considered. The first examined expenditure according to chronological time (calendar quarter) for all cancer patients in the database in a given quarter. The second examined only the most recent quarter and constructed a hypothetical expenditure life cycle by taking into consideration the number of quarters since the respective patient had her first claim.
Results: We found different average expenditures using the same data and over the same time period. The longitudinal measurement had less extreme peaks and troughs, and yielded average expenditure in the final period that was 60% higher than that produced using the cross-sectional analysis; however, the longitudinal analysis had intermediate periods with significantly lower estimated expenditure than the cross-sectional data.
Conclusions: These disparate results signify that each of the methods has merit. The longitudinal method tracks changes over time while the cross-sectional approach reflects more recent data, e.g. current practice patterns. Thus, this study reiterates the importance of considering the methodology when projecting future cancer expenditure.
KeywordsLetrozole Average Expenditure Future Expenditure Medicaid Reimbursement Chronological Time
This research was supported by the University of Maryland, Maryland Statewide Health Network through the Maryland Cigarette Restitution Funds.
The data in this study was provided through co-operation with the Maryland Department of Health and Mental Hygiene.
The authors would like to acknowledge the assistance of Fadia T. Shaya, Ph.D., for her review and assistance in the preparation of this manuscript.
The authors have no conflicts of interest directly relevant to the content of this study.
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