The association of preoperative anemia and perioperative allogeneic blood transfusion with the risk of surgical site infection.
BACKGROUND
The purpose of the study was to investigate allogeneic blood transfusion (ABT) and preoperative anemia as risk factors for surgical site infection (SSI).


METHODS
A prospective, observational cohort of 5873 consecutive general surgical procedures at Basel University Hospital was analyzed to determine the relationship between perioperative ABT and preoperative anemia and the incidence of SSI. ABT was defined as transfusion of leukoreduced red blood cells during surgery and anemia as hemoglobin concentration of less than 120 g/L before surgery. Surgical wounds and resulting infections were assessed to Centers for Disease Control standards.


RESULTS
The overall SSI rate was 4.8% (284 of 5873). In univariable logistic regression analyses, perioperative ABT (crude odds ratio [OR], 2.93; 95% confidence interval [CI], 2.1 to 4.0; p < 0.001) and preoperative anemia (crude OR, 1.32; 95% CI, 1.0 to 1.7; p = 0.037) were significantly associated with an increased odds of SSI. After adjusting for 13 characteristics of the patient and the procedure in multivariable analyses, associations were substantially reduced for ABT (OR, 1.25; 95% CI, 0.8 to 1.9; p = 0.310; OR, 1.07; 95% CI, 0.6 to 2.0; p = 0.817 for 1-2 blood units and >or=3 blood units, respectively) and anemia (OR, 0.91; 95% CI, 0.7 to 1.2; p = 0.530). Duration of surgery was the main confounding variable.


CONCLUSIONS
Our findings point to important confounding factors and strengthen existing doubts on leukoreduced ABT during general surgery and preoperative anemia as risk factors for SSIs.
Weber
Walter P
WP
Department of General Surgery, the Blood Transfusion Centre, University Hospital of Basel, Basel, Switzerland.
Zwahlen
Marcel
M
Reck
Stefan
S
Misteli
Heidi
H
Rosenthal
Rachel
R
Buser
Andreas S
AS
Kaufmann
Mark
M
Oertli
Daniel
D
Widmer
Andreas F
AF
Marti
Walter R
WR
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000740:Anemia / Q000150:complications*; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications / Q000209:etiology*; D012307:Risk Factors; D013530:Surgical Wound Infection / Q000209:etiology*; D065227:Transfusion Reaction; D014184:Transplantation, Homologous; D055815:Young Adult