The performance of the EuroSCORE and the Society of Thoracic Surgeons mortality risk score: the gender factor

Abstract

The purpose of this study was to explore potential differences in the performance of the EuroSCORE and the STS mortality risk score in the prediction of operative mortality following cardiac surgery with special focus on the impact of gender. We retrospectively reviewed 3125 consecutive cases of coronary artery bypass surgery performed at our institution between 2001 and 2004. STS and EuroSCORE (logistic [E-log] and additive [E-add]) operative mortality risk scores were calculated for each patient and stratified by gender (female: n=692; male: n=2433). Mortality risk scores were compared between the STS and EuroSCORE using C-statistics and likelihood ratios (LR). Stratified by gender, the E-log and E-add correlated well with the STS (female: r=0.77, 0.78, PPC-statistics generated from logistic regression, both EuroSCORE models correctly modeled operative mortality compared to the STS. Among male patients, the EuroSCORE C-statistic (E-log, 0.808; E-add, 0.809; STS, 0.796) performed more comparable to the STS than female patients (E-log, 0.853; E-add, 0.855; STS, 0.827). Our results suggest that both the STS risk scores and the EuroSCORE are good predictors for operative mortality with slight advantage for the STS risk score. Combined with the ease of use, we conclude that the EuroSCORE is another viable, bedside instrument for surgeons looking for a preoperative assessment of mortality risk, particularly in female patients undergoing cardiac surgery.