Overuse of Troponin? A Comprehensive Evaluation of Testing in a Large Hospital System

Abstract

Troponin assays are integral to the diagnosis of acute myocardial infarction (AMI), but there is concern that testing is over utilized and may not conform to published guidelines. We reviewed all testing performed at 14 hospitals over 12 months and associated troponin values with the primary and secondary diagnoses for each visit. Troponin was determined to be negative, indeterminate or elevated based on reference ranges. The majority of troponin measurements were single, not serial (64%). The rate of AMI was low, with only 3.5% of tested patients having a primary or secondary diagnosis of AMI. Sensitivity, specificity and negative predictive value were excellent, exceeding 90%. However, positive predictive value was low, suggesting testing of populations with diseases known to be associated with elevated troponin levels in the absence of AMI. The majority (79%) of elevated troponin values were associated with primary diagnoses other than AMI. Only 28% of elevated troponins were associated with a primary or secondary diagnosis of AMI. These data suggest possible overuse of troponin testing in our healthcare system.

Inpatient Mortality and 30-Day Readmission Rates Associated with Troponin Testing in Patients without Acute Myocardial Infarction

“…There is a noted strong link between troponin values and overall prognosis. 8 We see similar findings here, noting that in nearly all categories of type 2 AMI except for CHF, TnI elevation is a poor prognostic marker in terms of mortality and 30-day readmission. Interestingly, even patients with TnI testing had worse outcomes on the whole.…”

“…Overall, these data appear consistent with recent reports from other larger observational studies from similar cohorts with regard to risk factors such as age, elevated creatinine, any smoking history, hypertension, diabetes, and/or hyperlipidemia. 8,9 For this analysis, we included all inpatient admissions with troponin testing, since patient demographics are known to influence readmission. Not surprisingly, we found patients with more comorbidities carry a higher rate of TnI testing, higher rate of positive TnI results, increased inpatient mortality, and higher 30-day readmission rates.…”

Single vs Serial Measurements of Cardiac Troponin Level in the Evaluation of Patients in the Emergency Department With Suspected Acute Myocardial Infarction

“…25 A previous multicenter study, in which 64% of troponin measurements were single assesssments, found that 79% of elevated troponin levels were associated with diagnoses other than AMI. 26 When the troponin test was first introduced for clinical use, it was thought to be specific for AMI because the population in which it was studied had a significantly higher prevalence of coronary artery disease. However, its current use in the general population and with hsTn has made it less specific for AMI when results are positive.…”

The trouble with troponin

“…More than 70% of elevated troponin values identified in our health care system are found in patients without AMI. 10 The positive predictive value of testing in our system is <30%. When utilization was reviewed, most testing occurred in patients unlikely to have AMI or in whom the diagnosis would not be expected.…”