Cost-effectiveness comparison of response strategies to a large-scale anthrax attack on the chicago metropolitan area: impact of timing and surge capacity.

Rapid public health response to a large-scale anthrax attack would reduce overall morbidity and mortality. However, there is uncertainty about the optimal cost-effective response strategy based on timing of intervention, public health resources, and critical care facilities. We conducted a decision analytic study to compare response strategies to a theoretical large-scale anthrax attack on the Chicago metropolitan area beginning either Day 2 or Day 5 after the attack. These strategies correspond to the policy options set forth by the Anthrax Modeling Working Group for population-wide responses to a large-scale anthrax attack: (1) postattack antibiotic prophylaxis, (2) postattack antibiotic prophylaxis and vaccination, (3) preattack vaccination with postattack antibiotic prophylaxis, and (4) preattack vaccination with postattack antibiotic prophylaxis and vaccination. Outcomes were measured in costs, lives saved, quality-adjusted life-years (QALYs), and incremental cost-effectiveness ratios (ICERs). We estimated that postattack antibiotic prophylaxis of all 1,390,000 anthrax-exposed people beginning on Day 2 after attack would result in 205,835 infected victims, 35,049 fulminant victims, and 28,612 deaths. Only 6,437 (18.5%) of the fulminant victims could be saved with the existing critical care facilities in the Chicago metropolitan area. Mortality would increase to 69,136 if the response strategy began on Day 5. Including postattack vaccination with antibiotic prophylaxis of all exposed people reduces mortality and is cost-effective for both Day 2 (ICER=$182/QALY) and Day 5 (ICER=$1,088/QALY) response strategies. Increasing ICU bed availability significantly reduces mortality for all response strategies. We conclude that postattack antibiotic prophylaxis and vaccination of all exposed people is the optimal cost-effective response strategy for a large-scale anthrax attack. Our findings support the US government's plan to provide antibiotic prophylaxis and vaccination for all exposed people within 48 hours of the recognition of a large-scale anthrax attack. Future policies should consider expanding critical care capacity to allow for the rescue of more victims.

Prospective diagnostic accuracy assessment of the HemosIL HS D-dimer to exclude pulmonary embolism in emergency department patients.

INTRODUCTION: Chest pain and shortness of breath are among the most common symptoms requiring immediate evaluation. Testing for pulmonary embolism (PE) has become easier and widespread due to D-dimer blood tests. Safe use of these tests is only possible if sensitivity is high and they are used in non-high probability patients. We evaluated diagnostic performance of the HemosIL HS D-dimer, which despite FDA approval in 2005, has been minimally reported in prospective standard clinical care. MATERIALS AND METHODS: We used a prospective observational study design to follow patients in a single center with the HemosIL HS ordered for symptoms of possible PE with positive test result if >243 ng/ml. The outcome was PE or deep venous thrombosis (DVT) at the time of presentation or subsequent 45 days determined by structured evaluation of imaging tests, phone, or medical record follow-up in all patients. RESULTS: 529 patients received a D-dimer and 4.7% were ultimately diagnosed with PE or DVT. The sensitivity of the HemosIL HS was 96.0% (95% CI; 79.6 to 99.9%) specificity was 65.7% (95% CI; 61.4 to 69.8%) and likelihood ratio negative was 0.06 (95% CI; 0.01 to 0.42). The probability of PE in patients with a negative D-dimer was 1/332 or 0.3% (95% CI; 0.01% to 1.67%). The receiver operator curve had an area under the curve of 0.87 and supported the current cut-point as optimal. CONCLUSIONS: The HemosIL HS D-dimer had high sensitivity, very low negative post-test probability and is useful in excluding PE in the acute care setting.