title: Rheumatoid arthritis is associated with higher ninety-day hospital readmission rates compared to osteoarthritis after hip or knee arthroplasty: a cohort study.
abstract: OBJECTIVE
  To examine whether an underlying diagnosis of rheumatoid arthritis (RA) or osteoarthritis (OA) impacts the 90-day readmission rates after total hip arthroplasty (THA) or total knee arthroplasty (TKA).
  
  
  METHODS
  We analyzed prospectively collected data from an integrated health care system, Total Joint Replacement Registry, of adults with RA or OA undergoing unilateral primary THA or TKA during 2009-2011. Adjusted logistic regression models for 90-day readmission were fit. Odds ratios with 95% confidence intervals (95% CIs) were calculated. Study year was an effect modifier for the outcome; therefore separate analyses were conducted for each of the 3 study years.
  
  
  RESULTS
  Of the 34,311 patients, 496 had RA and 33,815 had OA. Comparisons of RA and OA patients, respectively, were 73% and 61% women, 45% and 70% white, and patients had a mean age of 61 versus 67 years (P < 0.001). Crude 90-day readmission rates for RA and OA were 8.5% and 6.7%, respectively. The adjusted odds of 90-day readmission increased from year to year for RA compared to OA patients, from 0.89 (95% CI 0.46-1.71) in 2009 to 1.34 (95% CI 0.69-2.61) in 2010, and to 1.74 (95% CI 1.16-2.60) in 2011. The 2 most common readmission reasons were joint prosthesis infection (10.2%) and septicemia (10.2%) in RA and joint prosthesis infection (5.7%) and other postoperative infection (5.1%) in OA.
  
  
  CONCLUSIONS
  RA is a risk factor for 90-day readmission after primary THA or TKA. An increasing risk of readmissions noted in RA in 2011 is concerning and indicates that further studies should examine the reasons for this increasing trend.
authors.affiliation: VA Medical Center, Birmingham, School of Public Health, University of Alabama at Birmingham, and Mayo Clinic College of Medicine, Rochester, Minnesota.
authors.forename: Jasvinder A
authors.initials: JA
authors.lastname: Singh
authors.forename: Maria C S
authors.initials: MC
authors.lastname: Inacio
authors.forename: Robert S
authors.initials: RS
authors.lastname: Namba
authors.forename: Elizabeth W
authors.initials: EW
authors.lastname: Paxton
mesh_terms: D000368:Aged; D001172:Arthritis, Rheumatoid / Q000175:diagnosis / Q000503:physiopathology / Q000601:surgery*; D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects*; D019645:Arthroplasty, Replacement, Knee / Q000009:adverse effects*; D016009:Chi-Square Distribution; D005260:Female; D006621:Hip Joint / Q000503:physiopathology / Q000601:surgery*; D006801:Humans; D007719:Knee Joint / Q000503:physiopathology / Q000601:surgery*; D016014:Linear Models; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D015207:Osteoarthritis, Hip / Q000175:diagnosis / Q000503:physiopathology / Q000601:surgery*; D020370:Osteoarthritis, Knee / Q000175:diagnosis / Q000503:physiopathology / Q000601:surgery*; D010359:Patient Readmission; D011183:Postoperative Complications / Q000175:diagnosis / Q000628:therapy; D012042:Registries; D012189:Retrospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D013997:Time Factors; D016896:Treatment Outcome