Study of the 99th-percentile reference value for sensitive cardiac troponin I assays in Egyptian population

Background To establish the 99th-percentile cutoff for sensitive cardiac troponin-I (cTnI) assay in Egyptian population. Patients and methods A sample size of 400 volunteers were divided into two groups [group A, including 200 participants without cardiovascular risk factors (CVRF), and group B, including 200 participants with more than 1 CVRF]. These two groups were used to create cardiac troponin-I (cTnI) 99th-percentile cutoffs, which were implied later on a third group of 100 patients suspected as myocardial infarction (MI) to illustrate the effect of the calculated values and to assess their precision in the diagnosis of MI. Results After calculation of the 99th percentile of each group, the present data revealed that the exclusion of CVRFs resulted in lowering of the calculated cutoffs from 0.05 to 0.038 ng/ml for group B and group A, respectively. Additionally, it has been clear that sex and age are important factors influencing the cTn concentrations. These lower values have predicted more patients at risk of having acute MI. There were correlations of troponin I with age, sex, and traditional risk factors. Conclusion Troponin-I concentrations in apparently healthy individuals rely on cardiac risk factors, sex, and age. Using the lower cutoff values after exclusion of risk factors led to prediction of more patients at risk compared with higher thresholds at the expense of specificity.