The interaction between pre-operative anaemia and peri-operative blood transfusion on patient outcomes following general surgical procedure: a retrospective review

AIM: To assess the incidence of pre-operative anaemia in patients presenting for general surgery and determine the relationship between pre-operative anaemia, transfusion and post-operative metrics including length of stay (LOS) and infectious complications. METHOD: A retrospective cohort of 1,186 patients. Stratification into two groups with and without pre-operative anaemia through propensity score matching. Logistic regression was used to determine the relationship between pre-operative anaemia, blood transfusion and infectious complications. RESULTS: The incidence of pre-operative anaemia was 17.4%. Red blood cell (RBC) transfusion was greater in those with PA than those without, 13.1% versus 0.7% (OR 21.7 (2.9-166.7, p<0.001)). In the propensity matched cohort, pre-operative anaemia was associated with an increase in LOS from 2.1 to 3.0 days (p=0.006) and increased infectious complications from 6.4% to 18.4%, (OR 3.3 (1.4-7.7), p=0.004). The risk of infectious complications was amplified in the patients receiving RBC transfusion. After adjustment for transfusion, in patients with pre-operative anaemia the OR for infectious complications became 2.3 (0.95-5.7, p=0.06) for those not transfused and 5.5 (2.0-15.3, p=0.001) for those transfused. CONCLUSION: Pre-operative anaemia is associated with an increase in hospital LOS and infectious complications. When adjusted for transfusion the effect of pre-operative anaemia alone on hospital LOS and infectious complications is not statistically significant. Expeditious investigation and treatment of PA could reduce complications and save resources.