Playing by the Rules: Using Decision Rules Wisely Part 2, Nontraumatic Conditions
In part 2 of this 2-part review, the authors discuss validated clinical decision rules for nontraumatic conditions commonly encountered in the ED, and provide useful pearls and pitfalls pertaining to their use.
Most recently, a stepped-wedge, cluster randomized trial across 9 hospitals published in 2017 investigated the utility of the HEART score. Despite enrolling only 3648 patients out of the statistically required sample size of 6600, they found that the HEART score was not inferior to usual care and there was no significant difference in median length of stay, but health care resources were typically lower in the HEART score group.23
Comment: While derived in a less conventional manner, the HEART score has held up in several validation studies and appears poised to safely decrease health care costs and increase ED efficiency and throughput. As more US EDs look to adopt high sensitivity troponin biomarkers, prospective studies will be needed to determine the role of the HEART score in this setting.
Thrombolysis in Myocardial Infarction (TIMI) score
The Thrombolysis in Myocardial Infarction (TIMI) score was developed in 2000 as a tool to risk-stratify patients with a diagnosis of unstable angina (UA) and non–ST-elevation myocardial infarction (NSTEMI). The score was derived from 1 arm (2047 patients) of a study comparing heparin with enoxaparin for treatment of NSTEMI, and validated in the other 3 arms of the study (5124 patients). Multivariate logistic regression was used to develop 7 variables of equal weight:
Age greater than or equal to 65yo
Three or more cardiac risk factors
Known coronary artery disease (with stenosis greater than or equal to 50%)
Aspirin use in the past 7 days
Severe angina (2 or more episodes in the past 24 hours)
EKG ST changes greater than or equal to 0.5 mm
Positive serum cardiac biomarkers
The investigators found that with a higher score, there was progressive increase in adverse cardiac outcomes, with a c-statistic of 0.65.24 This score was subsequently validated across several existing databases evaluating various therapeutic interventions for UA/NSTEMI and remained statistically significant, with increasing risk for MI and mortality with increasing score.25,26
Given the success in predicting patient outcomes and identifying patients who could benefit from more aggressive care, the TIMI risk score was then applied to unselected ED chest pain patients. In a secondary analysis of a prospective observational cohort of 3929 patient visits, the TIMI score correlated to the risk for adverse outcomes, with a risk of 2.1% at score 0.27
