Each year about 6 million people suffering from chest pain arrive at hospital emergency departments (EDs), and doctors must decide whether they have unstable angina pectoris or are suffering from a heart attack (acute myocardial infarction, AMI). The price of missing an AMI diagnosis is high, with nearly twice as many deaths among AMI patients who are mistakenly discharged from the ED compared with those who are appropriately hospitalized.
Two computerized diagnostic aids may help ED staff make faster and more appropriate ED triage decisions for chest pain patients, and they also may reduce health care costs, according to a review of studies by Daniel B. Stryer, M.D., of the Center for Outcomes and Effectiveness Research, Agency for Healthcare Research and Quality. The Acute Cardiac Ischemia Time-Insensitive Predictive Instrument (ACI-TIPI) and the related Thrombolytic Predictive Instrument (TPI) are programmed into conventional computerized electrocardiographs (ECGs), which automatically compute and print out a patient's predicted outcomes based on characteristics of the ECG when the patient arrives at the ED.
The ACI-TIPI predicts a patient's probability of heart attack based on seven risk factors that range from pain in the chest or left arm to peaking or inversion of ECG T waves. The TPI, based on records from 13 major clinical trials and registries, is used to calculate 30-day and 1-year mortality and cardiac arrest probability within 48 hours with and without thrombolytic (clot-busting) therapy. Both instruments were developed, tested, and refined by researchers at Boston University, led by Harry Selker, M.D., and supported in part by the Agency for Healthcare Research and Quality (HS07360, HS08212).
Use of ACI-TIPI in a 10-hospital trial led to a decline from 15 to 12 percent in coronary care unit (CCU) admission rates and an increase from 49 to 52 percent in discharges to home among patients without cardiac ischemia. Appropriate hospitalization and CCU admission remained about the same for patients with AMI or unstable angina. If these results were reproduced nationally, it is estimated that use of the ACI-TIPI could result in savings of $728 million by avoiding unnecessary CCU admissions and hospitalizations. Results from recent clinical trials of the two instruments are expected to be published soon and should lead to a greater understanding of their effects.
See "The development and role of predictive instruments in acute coronary events: Improving diagnosis and management," by Dr. Stryer, in the April 2002 Journal of Cardiovascular Nursing 16(3), pp. 1-8.
Reprints (AHRQ Publication No. 02-R064) are available from the AHRQ Publications Clearinghouse and AHRQ InstantFax.
Update: Select for information on the results of clinical trials of the two instruments.