Simplified model for end-stage liver disease score predicts mortality for tricuspid valve surgery

Abstract

Objectives: The model for end-stage liver disease score (MELD = 3.8*LN[total bilirubin] + 9.6*LN[creatinine] + 11.2*[PT-INR] + 6.4) predicts mortality for tricuspid valve surgery. However, the MELD is problematic in patients undergoing warfarin therapy, as warfarin affects the international normalized ratio (INR). This study aimed to determine whether a simplified MELD score that does not require the INR for calculation could predict mortality for patients undergoing tricuspid valve surgery. Simplified MELD score = 3.8*LN[total bilirubin] + 9.6*LN[creatinine] + 6.4.

Methods: A total of 172 patients (male: 66, female: 106; mean age, 63.8 ± 10.3 years) who underwent tricuspid replacement (n = 18) or repair (n = 154) from January 1991 to July 2011 at a single centre were included. Of them, 168 patients in whom the simplified MELD score could be calculated were retrospectively analysed. The relationship between in-hospital mortality and perioperative variables was assessed by univariate and multivariate analysis.

Results: The rate of in-hospital mortality was 6.4%. The mean admission simplified MELD score for the patients who died was significantly higher than for those surviving beyond discharge (11.3 ± 4.1 vs 5.8 ± 4.0; P = 0.001). By multivariate analysis, independent risk factors for in-hospital mortality included higher simplified MELD score (P = 0.001) and tricuspid valve replacement (P = 0.023). In-hospital mortality and morbidity increased along with increasing simplified MELD score. Scores <0, 0-6.9, 7-13.9 and >14 were associated with mortalities of 0, 2.0, 8.3 and 66.7%, respectively. The incidence of serious complications (multiple organ failure, P = 0.005; prolonged ventilation, P = 0.01; need for haemodialysis; P = 0.002) was also significantly higher in patients with simplified MELD score ≥ 7.

Conclusions: The simplified MELD score predicts mortality in patients undergoing tricuspid valve surgery. This model requires only total bilirubin and creatinine and is therefore applicable in patients undergoing warfarin therapy.

Figure 1:

ROC curve for simplified MELD score as a predictor of in-hospital mortality after tricuspid valve surgery. Areas under the curve (AUC) are 0.849. Youden index shows that the optimal cut-off point was 7.42.

Figure 2:

Operative mortality as a function of preoperative simplified MELD score.

Figure 3:

Distribution of the simplified MELD score in the study population.

Figure 4:

Simplified MELD scoring table. The horizontal axis shows creatinine (mg/dl), and the vertical axis shows total bilirubin (mg/dl). At the intersection, the corresponding simplified MELD score can be found. Pale pink indicates higher risk of death following tricuspid valve surgery, and orange indicates highest risk of death following tricuspid valve surgery.