title: Factors Affecting Readmission Rates Following Primary Total Hip Arthroplasty.
abstract: BACKGROUND
  Readmissions following total hip arthroplasty are a focus given the forthcoming financial penalties that hospitals in the United States may incur starting in 2015. The purpose of this study was to identify both preoperative comorbidities and postoperative conditions that increase the risk of readmission following total hip arthroplasty.
  
  
  METHODS
  Using the American College of Surgeons-National Surgical Quality Improvement Program data for 2011, a study population was identified using the Current Procedural Terminology code for primary total hip arthroplasty (27130). The sample was stratified into readmitted and non-readmitted cohorts. Demographic variables, preoperative comorbidities, laboratory values, operative characteristics, and surgical outcomes were compared between the groups using univariate and multivariate logistic regression models.
  
  
  RESULTS
  Of the 9441 patients, there were 345 readmissions (3.65%) within the first thirty days following surgery. Comorbidities that increased the risk for readmission were diabetes (p < 0.001), chronic obstructive pulmonary disease (p < 0.001), bleeding disorders (p < 0.001), preoperative blood transfusion (p = 0.035), corticosteroid use (p < 0.001), dyspnea (p = 0.001), previous cardiac surgery (p = 0.002), and hypertension (p < 0.001). A multivariate regression model was used to control for potential confounders. Having a body mass index of ≥40 kg/m2(odds ratio, 1.941 [95% confidence interval, 1.019 to 3.696]; p = 0.044) and using corticosteroids preoperatively (odds ratio, 2.928 [95% confidence interval, 1.731 to 4.953]; p < 0.001) were independently associated with a higher likelihood of readmission, and a high preoperative serum albumin (odds ratio, 0.688 [95% confidence interval, 0.477 to 0.992]; p = 0.045) was independently associated with a lower risk for readmission. Postoperative surgical site infection, pulmonary embolism, deep venous thrombosis, and sepsis (p < 0.001) were also independent risk factors for readmission.
  
  
  CONCLUSIONS
  The risk of readmission following total hip arthroplasty increases with growing preoperative comorbidity burden, and is specifically increased in patients with a body mass index of ≥40 kg/m2, a history of corticosteroid use, and low preoperative serum albumin and in patients with postoperative surgical site infection, a thromboembolic event, and sepsis.
  
  
  METHODS
  Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.
authors.affiliation: Department of Orthopaedic Surgery, Northwestern University, 676 North Saint Clair, Suite 1350, Chicago, IL 60611. E-mail address for H.M. Alvi: HashamAlvi@gmail.com.
authors.forename: Rachel E
authors.initials: RE
authors.lastname: Mednick
authors.affiliation: Department of Orthopaedic Surgery, Northwestern University, 676 North Saint Clair, Suite 1350, Chicago, IL 60611. E-mail address for H.M. Alvi: HashamAlvi@gmail.com.
authors.forename: Hasham M
authors.initials: HM
authors.lastname: Alvi
authors.affiliation: Department of Orthopaedic Surgery, Northwestern University, 676 North Saint Clair, Suite 1350, Chicago, IL 60611. E-mail address for H.M. Alvi: HashamAlvi@gmail.com.
authors.forename: Varun
authors.initials: V
authors.lastname: Krishnan
authors.affiliation: Department of Orthopaedic Surgery, Northwestern University, 676 North Saint Clair, Suite 1350, Chicago, IL 60611. E-mail address for H.M. Alvi: HashamAlvi@gmail.com.
authors.forename: Francis
authors.initials: F
authors.lastname: Lovecchio
authors.affiliation: Department of Orthopaedic Surgery, Northwestern University, 676 North Saint Clair, Suite 1350, Chicago, IL 60611. E-mail address for H.M. Alvi: HashamAlvi@gmail.com.
authors.forename: David W
authors.initials: DW
authors.lastname: Manning
mesh_terms: D000368:Aged; D019644:Arthroplasty, Replacement, Hip; D005260:Female; D006621:Hip Joint; D006801:Humans; D007592:Joint Diseases / Q000150:complications / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D010359:Patient Readmission / Q000706:statistics & numerical data*; D011183:Postoperative Complications / Q000453:epidemiology; D018570:Risk Assessment; D012307:Risk Factors; D014481:United States