title: Number of recent inpatient admissions as a risk factor for increased complications, length of stay, and cost in patients undergoing posterior lumbar fusion.
abstract: METHODS
  Retrospective cohort study.
  
  
  OBJECTIVE
  To identify risk factors for increased complication rate, hospital charges, and length of stay in patients undergoing posterior lumbar fusion.
  
  
  BACKGROUND
  A better understanding of risk factors for perioperative complications in patients undergoing posterior lumbar fusion can aid with patient selection and postoperative monitoring. Previous studies have assessed the impact of factors such as body mass index, age, and American Society of Anesthesiologists physical status classification on complication rate.
  
  
  METHODS
  Data were acquired from the institution's quality improvement data set. Preoperative demographic factors included sex, age, number of inpatient admissions in the prior year, body mass index, Charlson comorbidity score, American Society of Anesthesiologists physical status classification, number of levels fused, operative duration, and medications on admission. Complications recorded included pneumonia, myocardial infarction, venous thromboembolic event, hardware failure, readmission, or unplanned return to the operating room. Multivariate regression was used to identify predictors of increased complication rate, hospital charges, and length of stay.
  
  
  RESULTS
  A total of 462 patients were included. A history of more than 1 admission in the prior year was the only variable significantly associated with increased complication rate (odds ratio 10.56, P < 0.0001). History of more than 1 admission in the prior year (+1.92 d, P < 0.0001), operative duration more than 5 hours (+0.81 d, P = 0.008), and American Society of Anesthesiologists physical status classification 3 or greater (+0.75 d, P = 0.01) were associated with increased length of stay, whereas history of more than 1 admission in the prior year (+$27,798, P < 0.0001), fusion of 4 or more levels (+$38,043, P < 0.0001), and operative duration more than 5 hours (+$40,298, P < 0.0001) were associated with increased total charges.
  
  
  CONCLUSIONS
  The number of inpatient admissions in the prior year was found to be a more powerful predictor of perioperative risk after lumbar fusion than metrics evaluated in prior studies, such as age, body mass index, and comorbidities.
  
  
  METHODS
  3.
authors.affiliation: *Department of Orthopaedic Surgery, University of Chicago Medical Center, Chicago, IL †Reconstructive Spine Surgery, Illinois Bone and Joint Institute, Glenview, IL; and ‡Department of Orthopaedic Surgery, NorthShore University HealthSystem, Evanston, IL.
authors.forename: Ananth
authors.initials: A
authors.lastname: Eleswarapu
authors.forename: Mark M
authors.initials: MM
authors.lastname: Mikhael
authors.forename: Jason L
authors.initials: JL
authors.lastname: Koh
mesh_terms: D000368:Aged; D005260:Female; D017048:Health Care Costs; D006801:Humans; D007297:Inpatients; D007902:Length of Stay / Q000191:economics*; D008159:Lumbar Vertebrae / Q000601:surgery*; D008297:Male; D010343:Patient Admission / Q000191:economics / Q000706:statistics & numerical data*; D012189:Retrospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D013123:Spinal Fusion / Q000009:adverse effects* / Q000191:economics* / Q000295:instrumentation