title: Preoperative anemia increases postoperative morbidity in elective cranial neurosurgery.
abstract: BACKGROUND
  Preoperative anemia may affect postoperative mortality and morbidity following elective cranial operations.
  
  
  METHODS
  The American College of Surgeons National Surgical Quality Improvement Program (NSQIP) database was used to identify elective cranial neurosurgical cases (2006-2012). Morbidity was defined as wound infection, systemic infection, cardiac, respiratory, renal, neurologic, and thromboembolic events, and unplanned returns to the operating room. For 30-day postoperative mortality and morbidity, adjusted odds ratios (ORs) were estimated with multivariable logistic regression.
  
  
  RESULTS
  Of 8015 patients who underwent elective cranial neurosurgery, 1710 patients (21.4%) were anemic. Anemic patients had an increased 30-day mortality of 4.1% versus 1.3% in non-anemic patients (P < 0.001) and an increased 30-day morbidity rate of 25.9% versus 14.14% in non-anemic patients (P < 0.001). The 30-day morbidity rates for all patients undergoing cranial procedures were stratified by diagnosis: 26.5% aneurysm, 24.7% sellar tumor, 19.7% extra-axial tumor, 14.8% intra-axial tumor, 14.4% arteriovenous malformation, and 5.6% pain. Following multivariable regression, the 30-day mortality in anemic patients was threefold higher than in non-anemic patients (4.1% vs 1.3%; OR = 2.77; 95% CI: 1.65-4.66). The odds of postoperative morbidity in anemic patients were significantly higher than in non-anemic patients (OR = 1.29; 95% CI: 1.03-1.61). There was a significant difference in postoperative morbidity event odds with a hematocrit level above (OR = 1.07; 95% CI: 0.78-1.48) and below (OR = 2.30; 95% CI: 1.55-3.42) 33% [hemoglobin (Hgb) 11 g/dl].
  
  
  CONCLUSIONS
  Preoperative anemia in elective cranial neurosurgery was independently associated with an increased risk of 30-day postoperative mortality and morbidity when compared to non-anemic patients. A hematocrit level below 33% (Hgb 11 g/dl) was associated with a significant increase in postoperative morbidity.
authors.affiliation: Johns Hopkins, Department of Neurosurgery, 600 N Wolfe Street, Sheik Zayed Tower Room 6115G, Baltimore, Maryland, 21287, USA.
authors.forename: Mohamad
authors.initials: M
authors.lastname: Bydon
authors.affiliation: Johns Hopkins, Department of Neurosurgery, 600 N Wolfe Street, Sheik Zayed Tower Room 6115G, Baltimore, Maryland, 21287, USA.
authors.forename: Nicholas B
authors.initials: NB
authors.lastname: Abt
authors.affiliation: Johns Hopkins, Department of Neurosurgery, 600 N Wolfe Street, Sheik Zayed Tower Room 6115G, Baltimore, Maryland, 21287, USA.
authors.forename: Mohamed
authors.initials: M
authors.lastname: Macki
authors.affiliation: Johns Hopkins, Department of Neurosurgery, 600 N Wolfe Street, Sheik Zayed Tower Room 6115G, Baltimore, Maryland, 21287, USA.
authors.forename: Henry
authors.initials: H
authors.lastname: Brem
authors.affiliation: Johns Hopkins, Department of Neurosurgery, 600 N Wolfe Street, Sheik Zayed Tower Room 6115G, Baltimore, Maryland, 21287, USA.
authors.forename: Judy
authors.initials: J
authors.lastname: Huang
authors.affiliation: Johns Hopkins, Department of Neurosurgery, 600 N Wolfe Street, Sheik Zayed Tower Room 6115G, Baltimore, Maryland, 21287, USA.
authors.forename: Ali
authors.initials: A
authors.lastname: Bydon
authors.affiliation: Johns Hopkins, Department of Neurosurgery, 600 N Wolfe Street, Sheik Zayed Tower Room 6115G, Baltimore, Maryland, 21287, USA.
authors.forename: Rafael J
authors.initials: RJ
authors.lastname: Tamargo
keywords: Anemia; National Surgical Quality Improvement Program; cranial; hematocrit; hemoglobin; neurosurgery