Increased preoperative serum vitamin B12 level as a predictor of postoperative mortality in patients undergoing cardiac surgery

Serum vitamin B12 level is a useful prognostic marker for various conditions. The present study examined whether preoperative serum vitamin B12 level can predict mortality after cardiac surgery.

The present observational study comprised adult patients who underwent cardiac surgery at our institute between 2012 and 2019. The performance of preoperative vitamin B12 level in discriminating postoperative in-hospital mortality, the primary outcome of this study, was assessed by receiver operating characteristic (ROC) curve analysis. After dichotomizing vitamin B12 level using Youden's J Index, weighted logistic regression analysis was performed. Cumulative all-cause mortality, the secondary outcome, was also compared using the Kaplan-Meier estimator and Cox regression analysis.

A total of 973 patients were analyzed. The area under the ROC curve of vitamin B12 level for predicting in-hospital mortality was 0.76 (95% confidence interval [CI]: 0.73-0.78). Weighted logistic regression analysis revealed that the high vitamin B12 group (>726 pg/mL) had a significantly increased risk of in-hospital mortality compared to the low vitamin B12 group (adjusted odds ratio, 12.01; 95% CI: 7.73-18.67). The risk of mortality was higher in the high vitamin B12 group than the low vitamin B12 group (log-rank test, P<0.001; adjusted hazard ratio, 2.41; 95% CI: 1.70-2.39). In addition, the high vitamin B12 group had significantly poorer survival than the low vitamin B12 group, even within the same EuroSCORE II stratum (< or ≥4%; log-rank test, P<0.001 and P=0.001, respectively).

Preoperative measurement of serum vitamin B12 level may be an alternative for predicting the prognosis of patients undergoing cardiac surgery.