Impact of Anemia and Transfusion on Readmission and Length of Stay After Spinal Surgery

STUDY DESIGN: Retrospective cohort study. OBJECTIVE: To determine whether receipt of blood transfusion and preoperative anemia are associated with increased rates of 30-day all-cause readmission, and secondarily with a prolonged hospital stay after spinal surgery. SUMMARY OF BACKGROUND DATA: Increased focus on health care quality has led to efforts to determine postsurgical readmission rates and predictors of length of postoperative hospital stay. Although there are still no defined outcome measures specific to spinal surgery to which providers are held accountable, efforts to identify appropriate measures and to determine modifiable risk factors to optimize quality are ongoing. METHODS: Records from 1187 consecutive spinal surgeries at Northwestern Memorial Hospital in 2010 were retrospectively reviewed and data were collected that described the patient, surgical procedure, hospital course, complications, and readmissions. Presence or absence of transfusion during the surgery and associated hospital course was treated as a binary variable. Multivariate negative binomial regression and logistic regression were used to model length of stay and readmission, respectively. RESULTS: Nearly one fifth (17.8%) of surgeries received transfusions, and the overall readmission rate was 6.1%. After controlling for potential confounders, we found that the presence of a transfusion was associated with a 60% longer hospital stay [adjusted incidence rate ratio=1.60 (1.34-1.91), P<0.001], but was not significantly associated with an increased rate of readmission [adjusted odds ratio=0.81 (0.39-1.70), P=0.582]. Any degree of preoperative anemia was associated with increased length of stay, but only severe anemia was associated with an increased rate of readmission. CONCLUSIONS: Both receipt of blood transfusion and any degree of preoperative anemia were associated with increased length of hospital stay after controlling for other variables. Severe anemia, but not receipt of blood transfusion, was associated with increased rate of readmission. Our findings may help define actions to reduce length of stay and decrease rates of readmission.