Electronic Thesis and Dissertation Repository

Thesis Format



Master of Science


Epidemiology and Biostatistics


Zou, Guangyong

2nd Supervisor

Jairath, Vipul



Red blood cell transfusion is frequently used to treat the harmful effects of anemia in patients with acute upper gastrointestinal bleeding. However, there is no clear consensus on when red blood cell transfusion is warranted. No studies thus far have defined the optimal threshold for transfusion, and none have looked at whether volume of blood transfused is associated with clinical outcome. This thesis attempts to addresses these gaps by analyzing hemoglobin and volume of blood transfused as predictors of patient outcomes using multivariable logistic regression models. Main results showed a statistically significant interaction between initial hemoglobin and whether a patient received a transfusion, suggesting no apparent benefit to receiving a transfusion above hemoglobin concentrations of approximately 10.5g/dL. Risk of adverse outcomes also increased with increasing volume of blood transfused. These results could contribute to improving outcomes for patients with acute upper gastrointestinal, and identify opportunities for conservation of blood resources.

Summary for Lay Audience

Acute upper gastrointestinal bleeding (AUGIB) is a common gastrointestinal emergency treated in-hospital, and can be life-threatening if not properly managed. Red blood cell (RBC) transfusion is often used to combat the harmful effects of anemia in AUGIB patients. However, in cases of less severe, non-exsanguinating hemorrhage, it is not always clear when a RBC transfusion is warranted. A commonly used indication for RBC transfusion is blood hemoglobin (Hb) concentration; if a patient’s Hb falls too low, RBCs are transfused to restore hemodynamic stability. Previous clinical guidelines have endorsed an Hb threshold of 10g/dL, but recent trials have suggested this threshold can be safely lowered without adversely affecting patient outcomes. However, these trials have only compared arbitrary Hb thresholds, and have not focused on the optimal threshold for transfusion that best balances the risks of anemia against the risks of transfusion. Further, no trials thus far have investigated the association between volume of RBCs transfused and clinical outcomes. The aim of this study was to address these gaps in the literature by analyzing the association between Hb and clinical outcomes for patients who received a transfusion and those that did not (i.e., transfusion status), as well as the association between number of RBC units received and clinical outcomes. This was done by re-analyzing clinical data from the 2015 TRIGGER trial of 936 patients with AUGIB in the UK. Results showed a significant interaction between Hb at presentation and transfusion status, suggesting that receiving an RBC transfusion above Hb values of approximately 10.5g/dL significantly increased the patient’s probability of a negative health event such as death, re-bleeding, or other serious adverse events, within 28 days of hospital presentation. Further, patients who received more RBC units were at an increased risk of death and re-bleeding by study day 28, even after adjustment for baseline health of the patient. These results suggest the optimal threshold for RBC transfusion may not be as low as previously suggested in recent transfusion trials, and more focus should be paid to the appropriate volume of RBCs for transfusion, though further analysis of specific patient sub-groups is necessary.

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Creative Commons Attribution 4.0 License
This work is licensed under a Creative Commons Attribution 4.0 License.