Preoperative Anemia and Perioperative Outcomes in Patients Who Undergo Elective Spine Surgery

Study Design. Analysis of the prospectively collected American College of Surgeons National Surgical Quality Improvement Program database. Objective. To assess whether preoperative anemia predicted adverse, early, perioperative outcomes in patients undergoing elective spine surgery. Summary of Background Data. Prior studies have assessed the association of anemia with outcomes in various noncardiac surgical procedures. The association between preoperative anemia and 30-day outcomes for spine surgery is unknown. Methods. A total of 24,473 adults, classified as having severe (N = 88), moderate (N = 314), mild (N = 5477), and no anemia. Using propensity scores, patients with severe, mild, and moderate anemia were matched with patients with no anemia. Logistic regression was used to predict adverse postoperative outcomes. Sensitivity analyses were conducted limiting the study sample to patients who did not receive intra-or postoperative transfusion and to patients with and without preoperative cardiovascular comorbidities. Results. Patients with all levels of anemia had significantly higher risk of nearly all adverse outcomes than nonanemic patients in unadjusted and propensity-matched models. Patients with moderate and mild anemia were more likely to have prolonged length of hospitalization, experience 1 or more complications, and expire within 30 days of surgery compared with nonanemic patients. The association between anemia and adverse outcomes was found independently of intra-and postoperative transfusions, and was not more pronounced in patients with preoperative cardiovascular comorbidities. Conclusion. All levels of anemia were significantly associated with prolonged length of hospitalization and poorer operative or 30-day outcomes in patients undergoing elective spine surgery. Our findings, using a large multi-institutional sample of prospectively collected data, suggests that anemia should be regarded as an independent risk factor for perioperative and postoperative complications that deserves attention prior to elective spine surgery.