Abstract 740: Selection of Chest Pain Investigations in the Emergency Room: A Decision-Analytic Model for Low-risk CVD Patients
Background. The high predictive value of negative CT coronary angiography (CTA) has led to its proposal as the test of choice to select chest pain (CP) pts for early ER discharge. We sought to determine the conditions where CTA, SPECT and S/Echo would be the most efficient strategy with lowest costs and greatest health benefits.
Methods. The costs and outcomes for three investigative strategies:
SPECT with angiography for positive scans (basecase);
S/Echo with angiography for positive scans;
CTA plus angiography for severe and SPECT for moderate stenoses.
The reference case was based on CAD prevalence of 10%, prognostic sensitivity of CT of 10%, sensitivity and specificity of each test from meta-analyses, risks from the literature, and costs to the USA healthcare funder including a legal liability of $1,000,000 for failure to diagnose infarction. Sensitivity analyses were based on CAD prevalence, prognostic sensitivities and costs.
Results. In the reference case, the utility of S/Echo was inferior (0.803 QALYs vs 0.809 for CTA and SPECT) but the cost was less ($539 vs $540 vs $790). Compared to SPECT, S/Echo resulted in worse outcomes over the 1% to 30% CAD prevalence range whereas CTA resulted in better outcomes when CAD prevalence was <10%. CTA costs were consistently higher than SPECT whereas S/Echo was cost-saving at prevalence rates <10%. When CT prognostic sensitivity was <10%, SPECT was dominant strategy. S/Echo was the lowest cost strategy when the cost of angiography was <$385, at higher angiography costs SPECT was the lowest cost strategy.
Conclusions. The differences in efficacy between each of the test strategies are minor. SPECT is the optimal strategy when CAD prevalence was >10%; at low levels of CAD prevalence S/Echo is optimal. The prognostic sensitivity of CTA and the prevalence of CAD are critical determinants of relative effectiveness and cost for determining the most cost-effective test to select chest pain (CP) pts for early ER discharge.