title: Preoperative anemia does not predict complications after single-level lumbar fusion: a propensity score-matched multicenter study.
abstract: METHODS
  Multicenter retrospective cohort study.
  
  
  OBJECTIVE
  To estimate the impact of preoperative anemia on 30-day complications in patients undergoing single-level lumbar fusion.
  
  
  BACKGROUND
  Anemia has been widely implicated as a risk factor in various surgical procedures including elective spine surgery. No large-scale study has been performed to examine this relationship in single-level lumbar fusion surgery.
  
  
  METHODS
  The American College of Surgeons National Surgical Quality Improvement Program database was retrospectively reviewed to identify all patients who underwent single-level lumbar fusion procedures during 2006 to 2011. A propensity score-matching algorithm was used to match scores of anemic patients with that of nonanemic patients. Multivariate logistic regression analysis of unadjusted and propensity score-matched cohorts was performed to examine the effect of preoperative anemia on 30-day postoperative complication rates and length of hospital stay.
  
  
  RESULTS
  A total of 2960 patients met inclusion criteria. The propensity score-matching procedure yielded scores of 491 pairs of well-matched nonanemic and anemic patients. The multivariate analysis of propensity score-matched population found preoperative anemia to carry no significant association with any of the complications analyzed, including overall complications, medical complications, surgical complications, reoperation, mortality, or length of total hospital stay.
  
  
  CONCLUSIONS
  For patients undergoing single-level lumbar fusion, preoperative anemia is not independently associated with increased risk of 30-day complications or increased length of stay. Further studies are needed to independently validate this relationship in other spine surgical procedures.
  
  
  METHODS
  3.
authors.affiliation: *Rosalind Franklin University of Medicine and Science, Chicago Medical School, North Chicago, IL; and Departments of †Orthopaedic Surgery and ‡Surgery, Northwestern University, Feinberg School of Medicine, Chicago, IL.
authors.forename: Bobby D
authors.initials: BD
authors.lastname: Kim
authors.forename: Adam I
authors.initials: AI
authors.lastname: Edelstein
authors.forename: Alpesh A
authors.initials: AA
authors.lastname: Patel
authors.forename: Francis
authors.initials: F
authors.lastname: Lovecchio
authors.forename: John Y S
authors.initials: JY
authors.lastname: Kim
mesh_terms: D000328:Adult; D000368:Aged; D000740:Anemia / Q000175:diagnosis / Q000453:epidemiology*; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008159:Lumbar Vertebrae / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications / Q000175:diagnosis / Q000453:epidemiology* / Q000209:etiology; D011237:Predictive Value of Tests; D011300:Preoperative Care / Q000639:trends; D057216:Propensity Score; D011446:Prospective Studies; D012189:Retrospective Studies; D013123:Spinal Fusion / Q000009:adverse effects* / Q000639:trends