Risk stratification for in-hospital mortality after cardiac surgery: external validation of EuroSCORE II in a prospective regional registry.
OBJECTIVE
To evaluate performance of the European System for Cardiac Operation Risk Evaluation (EuroSCORE II), to assess the influence of model updating and to derive a hierarchical tree for modelling the relationship between EuroSCORE II risk factors and hospital mortality after cardiac surgery in a large prospective contemporary cohort of consecutive adult patients.


METHODS
Data on consecutive patients, who underwent on-pump cardiac surgery or off-pump coronary artery bypass graft intervention, were retrieved from Puglia Adult Cardiac Surgery Registry. Discrimination, calibration, re-estimation of EuroSCORE II coefficients and hierarchical tree analysis of risk factors were assessed.


RESULTS
Out 6293 procedures, 6191 (98.4%) had complete data for EuroSCORE II assessment with a hospital mortality rate of 4.85% and EuroSCORE II of 4.40 ± 7.04%. The area under the receiver operator characteristic curve (0.830) showed good discriminative ability of EuroSCORE II in distinguishing patients who died and those who survived. Calibration of EuroSCORE II was preserved with lower predicted than observed risk in the highest EuroSCORE II deciles. At logistic regression analysis, the complete revision of the model had most of re-estimated regression coefficients not statistically different from those in the original EuroSCORE II model. When missing values were replaced with the mean EuroSCORE II value according to urgency and weight of intervention, the risk score confirmed discrimination and calibration obtained over the entire sample. A recursive tree-building algorithm of EuroSCORE II variables identified three large groups (55.1, 17.1 and 18.1% of procedures) with low-to-moderate risk (observed mortality of 1.5, 3.2 and 6.4%) and two groups (3.8 and 5.9% of procedures) at high risk (mortality of 14.6 and 32.2%). Patients with low-to-moderate risk had good agreement between observed events and predicted frequencies by EuroSCORE II, whereas those at greater risk showed an underestimation of expected mortality.


CONCLUSIONS
This study demonstrates that EuroSCORE II is a good predictor of hospital mortality after cardiac surgery in an external validation cohort of contemporary patients from a multicentre prospective regional registry. The EuroSCORE II predicts hospital mortality with a slight underestimation in high-risk patients that should be further and better evaluated. The EuroSCORE II variables as a risk tree provides clinicians and surgeons a practical bedside tool for mortality risk stratification of patients at low, intermediate and high risk for hospital mortality after cardiac surgery.
Division of Cardiac Surgery, Department of Emergency and Organ Transplant, University of Bari Aldo Moro, Bari, Italy domenico.paparella@uniba.it.
Domenico
D
Paparella
Puglia Health Regional Agency, Bari, Italy.
Pietro
P
Guida
Department of Cardiac Surgery, Città di Lecce Hospital, Lecce, Italy.
Giuseppe
G
Di Eusanio
Department of Cardiac Surgery, Villa Bianca Hospital, Bari, Italy.
Sergio
S
Caparrotti
Department of Cardiac Surgery, Città di Lecce Hospital, Lecce, Italy.
Renato
R
Gregorini
Department of Cardiac Surgery, Santa Maria Hospital, Bari, Italy.
Mauro
M
Cassese
Department of Cardiac Surgery, Villa Verde Hospital, Taranto, Italy.
Vitantonio
V
Fanelli
Department of Cardiac Surgery, Anthea Hospital, Bari, Italy.
Giuseppe
G
Speziale
Department of Cardiac Surgery, Villa Bianca Hospital, Bari, Italy.
Valerio
V
Mazzei
Department of Cardiac Surgery, Vito Fazzi Hospital, Lecce, Italy.
Salvatore
S
Zaccaria
Division of Cardiac Surgery, Department of Emergency and Organ Transplant, University of Bari Aldo Moro, Bari, Italy.
Luigi De Luca Tupputi
Lde L
Schinosa
Division of Anesthesia, Department of Emergency and Organ Transplant, University of Bari Aldo Moro, Bari, Italy.
Tommaso
T
Fiore
D000368:Aged; D006348:Cardiac Surgical Procedures / Q000401:mortality*; D005260:Female; D006305:Health Status Indicators; D017052:Hospital Mortality; D006801:Humans; D007558:Italy / Q000453:epidemiology; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D015233:Models, Statistical; D011446:Prospective Studies; D012042:Registries; D018570:Risk Assessment; D016019:Survival Analysis
Cardiac surgery; EuroSCORE II; Risk analysis/modelling