Metaanalysis in clinical chemistry: validation of cardiac troponin T as a marker for ischemic heart diseases

Metaanalysis is a method that incorporates the pooling of previously published results to produce more statistically significant results. We used metaanalysis to examine the role of a new cardiac marker, cardiac troponin T (cTnT), in patients with ischemic heart disease. Metaanalysis of six articles and one abstract on cTnT showed that this marker was just as sensitive as creatine kinase MB isoenzyme (CK-MB) for the retrospective diagnosis of acute myocardial infarction (AMI) 12-48 h after onset but less specific. Most of these articles showed that cTnT was increased in non-AMI patients with unstable angina pectoris. In a metaanalysis of four papers, two abstracts, a letter, and an unpublished manuscript, we examined the prognostic role of cTnT in non-AMI cardiac patients. For an unfavorable endpoint defined as cardiac death, AMI, or the need for coronary artery revascularization, the results demonstrated that abnormal concentrations of cTnT were associated with a higher risk for a poor outcome than were normal concentrations of cTnT. We also compared cTnT with CK-MB for risk stratification. Metaanalysis will become an increasingly important tool for evaluating new tests as they become available.