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 (VIS_max) was calculated using the highest doses of vasoactive and inotropic medications administered during the first 24 h post-surgery. We established five VIS_max categories: 0-5, >5-15, >15-30, >30-45, and >45 points. The predictive accuracy of VIS_max was evaluated for a composite outcome, which included 30-day mortality, mediastinitis, stroke, acute kidney injury, and myocardial infarction.

Results: VIS_max 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 VIS_max group (>45). VIS_max 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 VIS_max 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, VIS_max 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.

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 VIS_max, SOFA, SAPS II, and APACHE II. VIS_max 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; VIS_max, maximum vasoactive-inotropic score.

Fig 3

Proportional incidence of outcomes in each VIS_max 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). VIS_max maximum vasoactive-inotropic score.

Fig 4

Survival curves for each VIS_max group. VIS_max 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). VIS_max maximum vasoactive-inotropic score.