Applying cardiac CT to the evaluation of patients who present to the emergency department (ED) with chest pain at low to intermediate risk of acute coronary syndrome saved money in both the initial diagnosis and over a one-year period, according to a decision analytic model published in the January issue of Academic Radiology .
Chest pain accounts for 5 percent of all ED visits and cumulative costs for evaluation of acute chest pain reached $12 billion in the U.S. in 2008. Previous studies have suggested that cardiac CT-based evaluation of low to intermediate risk patients may be less expensive than the standard of care. However, some stakeholders have suggested downstream costs associated with CT may tip the balance in favor of the standard of care. To date, no studies had accounted for both current and downstream costs associated with cardiac CT, according to researchers.
Kelley R. Branch, MD, MS, from the division of cardiology at University of Washington in Seattle, and colleagues devised a model to test the hypothesis that CT-based evaluation of patients at low to intermediate risk of acute coronary syndrome (ACS) would be less expensive than the standard of care even when downstream costs are included in the analysis.
The prospective cohort study included low to intermediate risk patients who presented to the ED with possible ACS between July 2006 and May 2009. All patients underwent cardiac CT and standard of care, which included a chest x-ray, serial ECGs, serial troponin and stress myocardial perfusion imaging as well as additional tests at the discretion of the physician. CT findings were reported as negative at less than 30 percent stenosis or not negative at more than 30 percent stenosis.
Patients were contacted at three, six and nine months after the initial ED visit to determine additional costs.
The researchers constructed decision trees for standard of care and cardiac CT models and calculated costs based on the 2007 Medicare fee schedule, with the exception of cardiac imaging which used the 2010 schedule to account for lower reimbursement over time. Branch and colleagues also evaluated various scenarios which could affect costs, including levels of ACS prevalence and application of cardiac CT in very low risk patients.
After completing the analysis, the researchers determined the mean estimated cost for obtaining a correct diagnosis using the base case values was $3,127 for standard of care and $2,384 for cardiac CT, which translates into a $750 savings for CT-based evaluation. The main source of savings was the difference between reimbursement for a nuclear stress test and cardiac CT.
According to the researchers’ analyses, CT became more expensive than standard of care when its specificity was reduced to less than 67 percent. CT remained less expensive across nearly 99 percent of probable scenarios, according to Branch et al.
Branch and colleagues noted that unlike previous studies the current study included actual data from CT patients who underwent both types of evaluations and included downstream costs.
The researchers cautioned that expanding CT to very low risk patients could cut into cost savings. “Based on these findings, the most substantial cost savings for cardiac CT evaluation would be in lower risk patients who would otherwise have a standard of care cardiac evaluation that included ED observation and stress testing,” Branch and colleagues concluded.