The TIMI risk score for unstable angina/non-ST elevation MI - A method forprognostication and therapeutic decision making

Context Patients with unstable angina/non-ST-segment elevation myocardial i nfarction (MI) (UA/NSTEMI) present with a wide spectrum of risk for death a nd cardiac ischemic events. Objective To develop a simple risk score that has broad applicability, is e asily calculated at patient presentation, does not require a computer, and identifies patients with different responses to treatments for UA/NSTEMI. Design, Setting, and Patients Two phase 3, international, randomized, doubl e-blind trials (the Thrombolysis in Myocardial Infarction [TIMI] 11B trial [August 1996-March 1998] and the Efficacy and Safety of Subcutaneous Enoxap arin in Unstable Angina and Non-Q-Wave MI trial [ESSENCE; October 1994-May 1996]). A total of 1957 patients with UA/NSTEMI were assigned to receive un fractionated heparin (test cohort) and 1953 to receive enoxaparin in TIMI 1 1B; 1564 and 1607 were assigned respectively in ESSENCE. The 3 validation c ohorts were the unfractionated heparin group from ESSENCE and both enoxapar in groups. Main Outcome Measures The TIMI risk score was derived in the test cohort by selection of independent prognostic variables using multivariate logistic regression, assignment of Value of 1 when a factor was present and 0 when i t was absent, and summing the number of factors present to categorize patie nts into risk strata. Relative differences in response to therapeutic inter ventions were determined by comparing the slopes of the rates of events wit h increasing score in treatment groups and by testing for an interaction be tween risk score and treatment. Outcomes were TIMI risk score for developin g at least 1 component of the primary end point (all-cause mortality, new o r recurrent MI, or severe recurrent ischemia requiring urgent revasculariza tion) through 14 days after randomization. Results The 7 TIMI risk score predictor variables were age 65 years or olde r, at least 3 risk factors for coronary artery disease, prior coronary sten osis of 50% or more, ST-segment deviation on electrocardiogram at presentat ion, at least 2 anginal events in prior 24 hours, use of aspirin in prior 7 days, and elevated serum card iac markers. Event rates increased significa ntly as the TIMI risk score increased in the test cohort in TIMI 11B: 4.7% for a score of 0/1; 8.3% for 2; 13.2% for 3; 19.9% for 4; 26.2% for 5; and 40.9% for 6/7 (P<.001 by chi(2) for trend). The pattern of increasing event rates with increasing TIMI risk score was confirmed in all 3 validation gr oups (P<.001). The slope of the increase in event rates with increasing num bers of risk factors was significantly lower in the enoxaparin groups in bo th TIMI 11B (P=.01) and ESSENCE (P=.03) and there was a significant interac tion between TIMI risk score and treatment (P=.02). Conclusions In patients with UA/NSTEMI, the TIMI risk score is a simple pro gnostication scheme that categorizes a patient's risk of death and ischemic events and provides a basis for therapeutic decision making.