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PROACT-4: Point-of-care troponin testing fails to shorten patient disposition time
ORLANDO, Fla. — Troponin testing performed in the ambulance significantly reduced the time before troponin values were available for patients presenting with chest pain, but testing did not significantly reduce time to disposition compared with usual care, according to results of the PROACT-4 study.
The trial included 601 patients with chest pain who were treated in 25 ambulances within the Edmonton, Alberta, Canada, EMS system between July 2013 and February 2015. Besides standard care, paramedics also randomly assigned eligible participants to usual care alone (n = 296) or point-of-care troponin in the ambulance (n = 305) upon receipt of verbal consent. Patients were eligible for inclusion if they were older than 30 years; had symptoms of acute chest pain with CVD as the most probable diagnosis; and did not have STEMI on ECG, cardiac arrest or pain compatible with other causes such as asthma or trauma.
Paramedics performed troponin testing using the Cardio2 Troponin I assay (Alere Inc.), which generated results within 15 to 18 minutes that were provided to ED staff upon arrival at the hospital.
The primary outcome was the time to disposition, defined as the time between first medical contact (arrival of the ambulance) to patient disposition in the hospital.
Results of troponin testing were available within 38 minutes for the point-of-care group compared with 138 minutes in the usual-care group (P < .001), Justin A. Ezekowitz, MBBCh, associate professor of medicine in the division of cardiology at University of Alberta, said during a presentation. He noted that troponin levels were less than 0.01 ng/mL in 64.3% of patients in the point-of-care group, with values greater than 0.03 ng/mL observed in 9.8% of the population. In-hospital troponin levels exceeded 0.1 ng/mL in 9.5% of the usual-care group vs. 14% of the point-of-care troponin group.
In intention-to-treat analysis, the time from first medical contact to final disposition was 8.85 hours in the point-of-care troponin group vs. 9.14 hours in the usual-care group; however, this difference was not significant (P = .069 for unadjusted analysis; P = .074 after adjustment for modified GRACE score). The time until patient discharge from the ED was shorter in the point-of-care troponin group (8.88 hours vs. 9.32 hours; unadjusted P = .021; adjusted P = .017), but the time until patient admission did not differ between the groups (8.62 hours vs. 8.73 hours). Results of a per-protocol analysis were similar.
Ezekowitz noted that the two groups did not differ with regard to 30-day rates of all-cause mortality, rehospitalization or return visits to the ED.
The final diagnosis was ACS for 112 cases, angina in 24 cases and acute HF in 16 cases. Non-cardiac diagnoses were made for the remaining patients. Using a threshold of greater than 0.03 ng/mL for point-of-care troponin values to indicate ACS, researchers calculated a sensitivity of 44%, specificity of 96%, positive predictive value of 73% and negative predictive value of 87%.
“Point-of-care troponin in the ambulance shortened the time to final disposition in ED, although this was not statistically significant in our primary endpoint,” Ezekowitz concluded. However, he added that point-of-care testing will continue to evolve with regard to speed, ease of use and sensitivity, and that it “will provide a potential opportunity in a low-risk population to streamline pre-ED and ED care, as well as for triage and pre-hospital therapy [in a high-risk population].” – by Adam Taliercio
Reference:
Ezekowitz JA, et al. Late-Breaking Clinical Trials 3. Presented at: American Heart Association Scientific Sessions; Nov. 7-11, 2015; Orlando, Fla.
Disclosure: One researcher is an employee of Alere Inc. Ezekowitz and the other researchers report no relevant financial disclosures.
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This is a very integrated system, which may be difficult to apply to many places in the United States, but if we can begin to implement procedures like this, where we can get a quick diagnosis in the ambulance, that might streamline things. The takeaway message is that there is something going on in the ED once the patient arrives at the hospital because they had a 100-minute head start on the diagnosis, and yet slowed down in the hospital. Based upon what we’ve seen so far, maybe we should start looking at systems of care in the ED. I know that in our ED, the doctors order lots of tests and patients sit around waiting for the results to come back. If you have a good, up-front test with a high negative predictive value, which [the researchers] showed, you could really streamline things. Maybe you don’t need 9 hours to rule something out; maybe you could do it with repeated studies over the course of 3 hours.