title: Periprosthetic shoulder infection in the United States: incidence and economic burden.
abstract: BACKGROUND
  Periprosthetic joint infection (PJI) is a major cause of morbidity after shoulder arthroplasty. PJI epidemiology has not been well studied. We aimed to analyze the historical incidence, predisposing factors, and economic burden of PJI after shoulder arthroplasty in the United States.
  
  
  METHODS
  Primary shoulder arthroplasty patients were identified by the International Classification of Diseases, Ninth Revision, Clinical Modification codes 81.80 (total shoulder arthroplasty), 81.81 (hemiarthroplasty), and 81.88 (reverse arthroplasty) in the Nationwide Inpatient Sample from 2002 to 2011. PJI was identified by codes 80.01 (arthrotomy for device removal) and 996.66 (prosthetic infection). Multivariate logistic regression analysis was used to identify predisposing factors for PJI.
  
  
  RESULTS
  PJI rate was 0.98% from 2002 to 2011 and did not vary significantly. Comorbidities associated with PJI were weight loss/nutritional deficiency (odds ratio [OR], 2.62; 95% confidence interval [CI], 1.53-4.51; P = .00047), drug abuse (OR, 2.38; 95% CI, 1.41-4.02; P = .0011), and anemia from blood loss (OR, 2.43; 95% CI, 1.50-3.93; P = .00031) or iron deficiency (OR, 2.05; 95% CI, 1.69-2.49; P < .0001). Demographic factors associated with PJI were younger age (OR, 1.020; 95% CI, 1.017-1.024; P < .0001) and male gender (OR, 1.961; 95% CI, 1.816-2.117; P < .0001). In 2011, median hospitalization costs for PJI were $17,163.57 compared with $16,132.68, $13,955.83, and $20,007.87 for total shoulder arthroplasty, hemiarthroplasty, and reverse arthroplasty, respectively.
  
  
  CONCLUSIONS
  Increasing incidence of shoulder arthroplasty and a constant infection rate will result in greater overall PJI burden. Whereas hospitalization costs for PJI are comparable to those of primary arthroplasty, they are incurred after the original cost of shoulder arthroplasty. Certain identifiable patient variables correlate with higher PJI rates. Risk factor modification may decrease PJI incidence and help contain costs.
authors.affiliation: Department of Orthopaedic Surgery, Rothman Institute, Thomas Jefferson University, Philadelphia, PA, USA.
authors.forename: Eric M
authors.initials: EM
authors.lastname: Padegimas
authors.affiliation: Department of Orthopaedic Surgery, Rothman Institute, Thomas Jefferson University, Philadelphia, PA, USA.
authors.forename: Mitchell
authors.initials: M
authors.lastname: Maltenfort
authors.affiliation: Department of Orthopaedic Surgery, Rothman Institute, Thomas Jefferson University, Philadelphia, PA, USA.
authors.forename: Matthew L
authors.initials: ML
authors.lastname: Ramsey
authors.affiliation: Department of Orthopaedic Surgery, Rothman Institute, Thomas Jefferson University, Philadelphia, PA, USA.
authors.forename: Gerald R
authors.initials: GR
authors.lastname: Williams
authors.affiliation: Department of Orthopaedic Surgery, Rothman Institute, Thomas Jefferson University, Philadelphia, PA, USA.
authors.forename: Javad
authors.initials: J
authors.lastname: Parvizi
authors.affiliation: Department of Orthopaedic Surgery, Rothman Institute, Thomas Jefferson University, Philadelphia, PA, USA. Electronic address: surena.namdari@rothmaninstitute.com.
authors.forename: Surena
authors.initials: S
authors.lastname: Namdari
mesh_terms: D000367:Age Factors; D018798:Anemia, Iron-Deficiency / Q000453:epidemiology; D019643:Arthroplasty, Replacement / Q000009:adverse effects / Q000191:economics / Q000706:statistics & numerical data*; D015897:Comorbidity; D020878:Device Removal; D005260:Female; D017048:Health Care Costs / Q000706:statistics & numerical data*; D062785:Hemiarthroplasty / Q000009:adverse effects / Q000191:economics / Q000706:statistics & numerical data; D006760:Hospitalization / Q000191:economics; D006761:Hospitals / Q000706:statistics & numerical data; D006801:Humans; D015994:Incidence; D007595:Joint Prosthesis / Q000009:adverse effects*; D008297:Male; D044342:Malnutrition / Q000453:epidemiology; D016459:Prosthesis-Related Infections / Q000191:economics* / Q000453:epidemiology*; D012307:Risk Factors; D012737:Sex Factors; D012785:Shoulder Joint / Q000601:surgery*; D019966:Substance-Related Disorders / Q000453:epidemiology; D014481:United States / Q000453:epidemiology
keywords: Nationwide Inpatient Sample; Shoulder periprosthetic joint infection; cost analysis; reverse shoulder arthroplasty; risk factor analysis; shoulder arthroplasty; shoulder hemiarthroplasty