title: Preoperative anemia and perioperative outcomes in patients who undergo elective spine surgery.
abstract: METHODS
  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.
  
  
  BACKGROUND
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Epidemiology and Biostatistics, Case Western Reserve University School of Medicine, Cleveland, OH 44195, USA. aas33@case.edu
authors.forename: Andreea
authors.initials: A
authors.lastname: Seicean
authors.forename: Sinziana
authors.initials: S
authors.lastname: Seicean
authors.forename: Nima
authors.initials: N
authors.lastname: Alan
authors.forename: Nicholas K
authors.initials: NK
authors.lastname: Schiltz
authors.forename: Benjamin P
authors.initials: BP
authors.lastname: Rosenbaum
authors.forename: Paul K
authors.initials: PK
authors.lastname: Jones
authors.forename: Michael W
authors.initials: MW
authors.lastname: Kattan
authors.forename: Duncan
authors.initials: D
authors.lastname: Neuhauser
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Weil
mesh_terms: D000328:Adult; D000368:Aged; D000740:Anemia / Q000453:epidemiology* / Q000473:pathology; D015897:Comorbidity; D017558:Elective Surgical Procedures / Q000009:adverse effects / Q000379:methods*; D005260:Female; D006801:Humans; D007902:Length of Stay / Q000706:statistics & numerical data; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D019637:Orthopedic Procedures / Q000009:adverse effects / Q000379:methods*; D017063:Outcome Assessment, Health Care / Q000706:statistics & numerical data; D011183:Postoperative Complications / Q000453:epidemiology* / Q000209:etiology; D057234:Preoperative Period; D011446:Prospective Studies; D018570:Risk Assessment / Q000706:statistics & numerical data; D012307:Risk Factors; D012720:Severity of Illness Index; D013997:Time Factors; D014481:United States / Q000453:epidemiology