Evaluation of the effect of older age on the diagnostic specificity of high-sensitivity troponin I and high-sensitivity troponin T in patients with suspected acute myocardial infarction

Abstract

Background Cardiac troponins have become the gold standard for appropriate and rapid diagnosis of an acute myocardial infarction (AMI). However, elevated cardiac troponins levels can be observed in the absence of AMI in elderly patients and therefore a loss of specificity is seen in the diagnosis of AMI in elderly patients. Purpose This study aims to define old age in suspected AMI and to evaluate the effect of older age on the diagnostic specificity of a high sensitivity troponin I (hs-cTnI) and high sensitivity troponin T (hs-cTnT) assay in elderly women and men. Methods This study used data from patients with suspected AMI who were enrolled between 08–2011 and 10–2016 to a multicentre biomarker registry and an University Hospital and with available hs-cTnI and hs-cTnT upon admission (n=564 patients). First, we investigated the effect of age on the specificity of both hs-cTnI and hs-cTnT to detect AMI continuously. We then classified over seventy-year-olds as elderly (n=281; 49,8%) and compared the specificity of hs-cTnI and hs-cTnT between elderly and younger patients. Results In the group of older patients, 62.6% (n=176) were diagnosed with AMI compared with 50.9% (n=144) in younger age patients (p<0.01). Elderly patients had higher median levels of hs-cTnI and hs-cTnT than younger patients: 45.4 ng/L vs. 13.1 ng/L hs-cTnI (p<0.001) and 36.8 ng/L vs. 12.8 ng/L hs-cTnT (p<0.001) irrespective of the final diagnosis. Figure1 shows a shift in diagnostic specificity for the whole troponin concentration range in elderly patients compared to younger patients starting at the age of 60 years with clear impact in patients older than 70 years used as threshold for old age in further analyses. Applying the 99th percentile cut-off led to a specificity of 93.5% (95% CI: 88.1–97.0%) in younger patients vs. 88.6% (95% CI: 80.9–94.0%) in elderly patients for hs-cTnI and of 91.4% (95% CI: 85.4–95.5%) vs. 65.7% (95% CI: 55.8–74.7%) for hs-cTnT. To achieve the same specificity in elderly patients as in younger patients, optimized rule-in cut-offs were calculated with 2.6-fold of the 99th percentile for hs-cTnI (68.9 ng/L) and 3.1-fold of the 99th percentile for hs-TnT (43.9 ng/L). Conclusions The specificity of both, hs-cTnI and hs-cTnT is significantly reduced in elderly patients due to higher hs-cTnT and hs-cTnI levels in elderly patients at admission irrespective of the final diagnosis. A relevant loss in diagnostic specificity is observed at 70 years of age starting already at 60 years. Use of assay-specific adjusted cut-offs for hs-cTnI and hs-cTnT for elderly patients regains diagnostic specificity that leads to a more accurate decision-making concerning “rule-in” for older patients with suspected AMI. Funding Acknowledgement Type of funding source: None