Prediction of Death After Noncardiac Surgery: Potential Advantage of Using High‐Sensitivity Troponin T as a Continuous Variable

BACKGROUND: Increased high‐sensitivity cardiac troponin T (hs‐cTnT) above the upper reference limit (URL) after noncardiac surgery identifies patients at risk for mortality. Prior studies have not analyzed hs‐cTnT as a continuous variable or probed age‐ and sex‐specific URLs. This study compared the prediction of 30‐day mortality using continuous postoperative hs‐cTnT levels to the use of the overall URL and age‐ and sex‐specific URLs. METHODS AND RESULTS: Patients (876) >40 years of age who underwent noncardiac surgery were included. Hs‐cTnT was measured on postoperative day 1. Cox proportional hazards models were used to compare associations between 30‐day mortality and using hs‐cTnT as a continuous variable, or above the overall or age‐ and sex‐specific URLs. Comparisons were performed by the area under the receiver operating characteristic curve analysis. Mortality was 4.2%. For each 1 ng/L increase in postoperative hs‐cTnT, there was a 0.3% increase in mortality (P<0.001). Patients with postoperative hs‐cTnT >14 ng/L were 37% of the cohort, while those above age‐ and sex‐specific URLs were 25.3%. Both manifested higher mortality (hazard ratio [HR], 3.19; 95% CI, 1.20–8.49; P=0.020) and (HR, 2.76; P=0.009) than those with normal levels. The area under receiver operating characteristic curve was 0.89 using hs‐cTnT as a continuous variable, 0.87 for age‐ and sex‐specific URLs, and 0.86 for the overall URL. CONCLUSIONS: Hs‐cTnT as a continuous variable was independently associated with 30‐day mortality and had the highest accuracy. Hs‐cTnT elevations using overall and/or age‐ and sex‐specific URLs were also associated with higher mortality.