Background
There is increasing evidence that anaemia is associated with worse outcomes, increased rates of blood transfusions and increased costs. There is a drive to treat anaemia preoperatively to optimise patients prior to surgery. Traditionally, cut off values, derived from the WHO of classification of anaemia have been used but whether these are appropriate in the perioperative setting and in different surgery types remain to be investigated.

Method
This is a retrospective review of a prospective held database of 377 consecutive patients undergoing major hepatobiliary surgery at a single centre over 30 months. Caldicott approval was granted for the study. A number of factors were examined including preoperative haemoglobin, transfusion rates, age, sex, duration of surgery, length of critical care (all patients returned to a critical care environment) and hospital stay and in-hospital mortality rates. The primary outcomes were to examine whether transfusion was associated with prolonged hospital stay and whether preoperative Hb was associated with increased transfusion rates. 

Results
We had complete data recorded for the 377 consecutive patients between May 2015 and August 2017 undergoing major hepatobiliary surgery. The perioperative blood transfusion rate was 22.3%. Unsurprisingly, blood transfusion was associated with increased duration of surgery suggesting it was of a more complex nature. Both critical care (1.9 vs 10.2 p<0.001) and hospital length of stay were dramatically increased (14.2 (12.1) vs 35.1 (34.1) p<0.001). The in-hospital mortality rate was 1.9%. Of those that died all had received a blood transfusion. 
Preoperative Hb levels were significantly reduced in those requiring a preoperative blood transfusion (119 (19.7) vs 135.75 (14.5) p<0.001. ROC curve analysis revealed the optimum preop Hb to predict those at risk of blood transfusion was 125 (AUROC=0.75 95% CI 0.69 – 0.82 sens 78 spec 77 p<0.001). Using this cut of value for preoperative Hb, it was associated with four fold increase in the blood transfusion rates and also prolonged hospital and intensive care stay. 
Discussion
This retrospect study of patients undergoing major hepatobiliary surgery has revealed that preoperative anaemia is a potential reversible risk factor for blood transfusion and prolonged length of hospital and critical care stay. The potential cost savings by implementing a preoperative anaemia service as well as the reduction in the need for blood transfusion are massive and suggests that this needs to be explored further in this high risk group of patients. We believe this is the first time optimal Hb levels have been assessed to make the most cost effective treatment pathway. 


07 / Association between preoperative anaemia, blood transfusion rates and outcomes after major hepatobiliary surgery