Preoperative fibrinogen: a predictor for intraoperative blood transfusion during liver transplantation?

L. Betolaza, I. De la Hoz, L. Gajate, N. Gómez, L. Pereira.

BACKGROUND
Fibrinogen is a protein with a key role in the coagulation cascade, and thus a potential biomarker for bleeding. However, its use to predict the risk of bleeding during liver transplantation (LT) is still controversial. 
We investigated the relationship between preoperative fibrinogen levels and the need of blood transfusion during orthotopic liver transplantation.

STUDY DESIGN AND METHOD
A total of 266 patients undergoing orthotopic liver transplantation during the period between January 2006 and December 2015 were included in a retrospective study. 
We analyzed the differences in red blood cells (RBC) transfusion requierements between two groups (fibrinogen levels < 200 mg/dl vs fibrionogen levels ≥ 200 mg/dl). The primary end point was the percentage of patients who recieved at least one RBC transfusion during surgery. First we made a raw analysis of the difference between both groups using ji square test. Then we compared both cohorts looking for unbalanced variables. Then, once we identified all those posible confounding variables, we carried out a binary logistic regression analysis to assess the real relationship between preoperative fibrinogen levels and blood transfusion requierements in our sample. Statistical significant was considered for p<0.05 and two-tailed test. Continuos variables are described with means and standard deviations and categorical variables with percentages and absolute values. The criteria for transfusion were: RBC if Hb<8 g/dl, platelets if platelet count < 50.000/ml, and fresh frozen plasma if INR >2. Fibrinogen was administered according to the discretion of the anaesthesiologist.

RESULTS:
Our database included a total of 266 patients (200 men, 66 women), but the final analysis was performed with 251 patients because of missing data.
In the raw analysis the difference between both groups was statistically significant regarding the primary end point. In the cohort of patients with low fibrinogen levels, 86.7% received at least one RBC and in the other group 67.1% (OR 3.2; CI 1.7-6.1; p<0.001). In the univariate analysis, there were some variables disbalanced between groups. So, we conducted a multivariate analysis adjusting by those confounding factors (gender, preoperative urea level, proeperative INR and length of surgery). In the logistic regression analysis, preoperative fibrinogen level < 200 mg/dl was not a significant predictor for RBC transfusion during liver transplantation (OR 1.09; CI 0.49-2.62; p=0.84). Anyway, RBC transfusion was higher in the group with low levels (6.5 ± 7.8 vs 5.2 ± 6.1; p=0.16).
  

CONCLUSIONS:
Our data suggests that low preoperative fibrinogen level (once adjusted by gender, preoperative urea, INR and length of surgery), does not predict the need for RBC transfusion during liver transplantation. More studies are needed to assess the real paper of fibrinogen in liver transplantation