Prediction of death after noncardiac surgery: Potential advantage of using high-sensitivity troponin t as a continuous variable

Abstract

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 ac-curacy. Hs-cTnT elevations using overall and/or age-and sex-specific URLs were also associated with higher mortality.