Evaluation of sex-specific cut-off values of high-sensitivity cardiac troponin I and T assays in an emergency department setting - Results from the Linz Troponin (LITROP) study

Background: The aim of the present analysis was to evaluate sex-specific cut-off values of a high-sensitivity cardiac troponin T (hs-cTnT) assay and a high-sensitivity cardiac troponin I (hs-cTnI) assay in an emergency department setting. Methods: We retrospectively studied 1945 male and 1643 female emergency department patients in whom we had measured both Roche hs-cTnT and Abbott hs-cTnI routinely upon every troponin measurement request. We performed reclassification analyses of sex-specific thresholds versus sex-neutral thresholds of both assays. In addition, we performed sensitivity analyses to find those sex-specific cut-off values for the Roche hs-cTnT and the Abbott hs-cTnI assays with the lowest possible rate of discordant classifications by both assays. Results: Compared with the classification by the sex-neutral thresholds (i.e., 14 ng/L for hs-cTnT and 26 ng/L for hs-cTnI), using sex-specific thresholds (i.e., 16 ng/L in males and 9 ng/L in females for hs-cTnT; and in 34 ng/L males and 16 ng/L in females for hs-cTnI) resulted in a total reclassification rate of 4% for hs-cTnT and 3% for hs-cTnI in male individuals, and of 11% and 6%, respectively, in female individuals. In our cohort, the sex-specific hs-cTnT cut-off values currently in use (i.e., 16 ng/L in males and 9 ng/L in females) were best matched to a hs-cTnI cut-off value of 11 ng/L in male and 5 ng/L in female individuals. Conversely, the sex-specific hs-cTnI cutoff values currently in use (i.e., 34 ng/L in males and 16 ng/L in females) were best matched to a hs-cTnT cut-off value of 49 ng/L in male and 24 ng/L in female individuals. These "harmonised" cut-off values reduced discordant classifications between both assays by 43-68% compared to using cut-off values currently in use. Conclusion: Especially in women, reclassification rates were high, when using sex specific versus sex-neutral thresholds. Best matching cut-off values for hs-cTnT and hs-cTnI were markedly different to those currently in use. These "harmonised" cut-off values minimised discordant classifications between both assays.