Vasoactive-inotropic score and the prediction of morbidity and mortality after cardiac surgery

Abstract

Background: The vasoactive-inotropic score (VIS) predicts mortality and morbidity after paediatric cardiac surgery. Here we examined whether VIS also predicted outcome in adults after cardiac surgery, and compared predictive capability between VIS and three widely used scoring systems.

Methods: This single-centre retrospective cohort study included 3213 cardiac surgery patients. Maximal VIS (VISmax) was calculated using the highest doses of vasoactive and inotropic medications administered during the first 24 h post-surgery. We established five VISmax categories: 0-5, >5-15, >15-30, >30-45, and >45 points. The predictive accuracy of VISmax was evaluated for a composite outcome, which included 30-day mortality, mediastinitis, stroke, acute kidney injury, and myocardial infarction.

Results: VISmax showed good prediction accuracy for the composite outcome [area under the curve (AUC), 0.72; 95% confidence interval (CI), 0.69-0.75]. The incidence of the composite outcome was 9.6% overall and 43% in the highest VISmax group (>45). VISmax predicted 30-day mortality (AUC, 0.76; 95% CI, 0.69-0.83) and 1-yr mortality (AUC, 0.70; 95% CI, 0.65-0.74). Prediction accuracy for unfavourable outcome was significantly better with VISmax than with Acute Physiology and Chronic Health Evaluation II (P=0.01) and Simplified Acute Physiological Score II (P=0.048), but not with the Sequential Organ Failure Assessment score (P=0.32).

Conclusions: In adults after cardiac surgery, VISmax predicted a composite of unfavourable outcomes and predicted mortality up to 1 yr after surgery.

Keywords: acute kidney injury; cardiac surgery; cardiovascular system; mortality; myocardial infarction; postoperative outcome; risk assessment scoring system; stroke.

Copyright © 2019 British Journal of Anaesthesia. Published by Elsevier Ltd. All rights reserved.

Figures

Fig 1

Study flowchart. Each patient was included only once, even when they had multiple re-admissions. Incidence of each adverse event is presented separately. ICU, Intensive care unit.

Fig 2

Receiver operating curves (ROC) of unfavourable outcome on VISmax, SOFA, SAPS II, and APACHE II. VISmax showed better discrimination capability than APACHE II, and SAPS II (Delong-method with P<0.05) and similar to SOFA (P=0.31). APACHE II, Acute Physiology and Chronic Health Evaluation II score; SAPS II, Simple Acute Physiology Score II; SOFA, Sequential Organ Failure Assessment score; VISmax, maximum vasoactive-inotropic score.

Fig 3

Proportional incidence of outcomes in each VISmax group. The 0–5 and >45 groups significantly differed from the other groups with regards to 30-day mortality (χ2 test, P<0.05). The groups 0–5, 5–30, and 30–45 significantly differed from one another in ICU length of stay (LOS) and myocardial infarct (MI) (χ2 test, P<0.05). VISmax maximum vasoactive-inotropic score.

Fig 4

Survival curves for each VISmax group. VISmax predicted cumulative mortality up to 1 yr. Mortality continuously increased within each group. There was no significant difference between the 0–5, >5–15, and >15–30 groups. The >30–45 and >45 groups significantly differed from each other and from the other groups (P=0.001). VISmax maximum vasoactive-inotropic score.