Abstract WP382: The Cost of Ischemic Stroke: The Superiority of Marginal over Total Cost Estimation and Its Impact on National Cost Estimates

Abstract

Introduction Cost of illness for ischemic stroke has historically been reported as mean cost per case over a time period. Such cost include expenditures made for comorbid conditions, and may result in an over-estimation of the economic burden of stroke on the nation. Without accurate estimates, policymakers cannot plan appropriately for the ageing US population. Hypothesis The 1-year marginal cost of stroke is less than the 1-year total cost of stroke for South Carolina (SC) Medicare beneficiaries. Methods A cost of illness analysis was performed from the Medicare perspective. SC Medicare billing files for 2004 and 2005 were used to estimate the mean 12 month cost of stroke for 2,976 Medicare beneficiaries hospitalized for ischemic Stroke in 2004. Using nearest neighbor propensity score matching, a control group of 5,952 non-stroke beneficiaries were matched on age, race, gender and comorbid conditions. Results The total cost estimated for stroke patients for 1 year was $81.3 million. The cost for the matched comparison group without stroke, but with similar age, gender, race and comorbid conditions was significantly less at $54.4 million (p<0.0001). Thus, the 2004 marginal costs to Medicare due to ischemic stroke in SC are estimated to be $26.9 million. If this difference is inflated to 2012 dollars and projected to estimate the 2012 one year burden of ischemic stroke nationally, total annual stroke costs would be overestimated by $4.89 billion. Conclusions Accurate estimates of cost of care for conditions, such as stroke, that are common in older patients with a high rate of comorbid conditions require the use of a marginal costing approach. Overestimation of cost of care for stroke may lead to erroneous funding allocation and prediction of larger savings than realizable from stroke treatment and prevention programs. Given the trend of policies based on cost savings, overestimation poses a danger of limiting services that patients may receive. Thus, it is important to use marginal costing for stroke program estimates, especially with the increasing public focus on evidence-based economic decision making to be expected with health reform.