Univariate analyses of potential predictor variables.

P values for chi square analyses with mortality as outcome. Initial hypotension is defined as systolic blood pressure (SBP)<90 or mean arterial pressure (MAP)<60 at the time of hospital presentation. Presence of comorbidities refers to any past medical history listed in the patient’s chart on hospital presentation. Low hemoglobin is a hemoglobin < 7 g/dL at any time before transfusion. Low oxygen saturation is a saturation <90% at any time before transfusion. Abnormal temperature is a temperature >38 or <36 degrees Celsius at any time before transfusion. Indication for transfusion (five categories) looked at whether any individual reason for transfusion (obstetric emergency, trauma, planned surgery, unplanned surgery, or other) were associated with mortality. Tachycardia refers to a heart rate (HR)>100 beats per minute at time of presentation or just before transfusion. Initial tachycardia refers to HR>100 beats per minute at time of hospital presentation. Abnormal platelet or coagulation labs refers to international normalized ratio of prothrombin time (INR)> = 1.5, partial thromboplastin time (PTT)> = 45 seconds or platelets<150 K/uL. Hypotension refers to SBP<90 or MAP<60 on presentation or just prior to transfusion. Distance from hospital is a categorical variable with categories of approximately equal size: 3–35, 36–100, 101–200, and >200 kilometers from the hospital.
Univariate analyses of potential predictor variables.