title: Comparing In-Hospital Total Joint Arthroplasty Outcomes and Resource Consumption Among Underweight and Morbidly Obese Patients.
abstract: As orthopedic surgeons search for objective measures that predict total joint arthroplasty (TJA) outcomes, body mass index may aid in risk stratification. The purpose of this study was to compare in-hospital TJA outcomes and resource consumption amongst underweight (body mass index ≤19 kg/m(2)) and morbidly obese patients (≥40 kg/m(2)).
  
  
  
  Discharge data from 2006 to 2012 National Inpatient Sample were used for this study. A total of 1503 total hip arthroplasty (THA) and 956 total knee arthroplasty (TKA) patients were divided into 2 cohorts, underweight (≤19 kg/m(2)) and morbidly obese (≥40 kg/m(2)). Patients were matched by gender and 27 comorbidities by use of Elixhauser Comorbidity Index. Patients were compared for 13 in-hospital postoperative complications, length of stay, total hospital charge, and disposition. Multivariate analyses were generated by SAS software. Significance was assigned at P value <.05.
  
  
  
  Underweight patients undergoing primary TJA had higher risk for developing postoperative anemia compared with morbidly obese patients (TKA: odds ratio [OR], 3.1; 95% CI, 2.3-4.1; THA: OR, 1.8; 95% CI, 1.5-2.3). Underweight THA candidates displayed greater risk for deep venous thrombosis (75.36% vs 24.64%; OR, 3.1; 95% CI, 1.1-8.4). Underweight TJA patients were charged more (TKA: USD 51,368.90 vs USD 40,128.80, P = .001, THA: USD 57,451.8 vs USD 42,776.9, P < .001) compared to the morbidly obese patients. Length of stay was significantly longer for underweight THA patients (4.6 days vs 3.5 days, P = .008) compared to morbidly obese counterparts.
  
  
  
  Our results indicate underweight, compared to morbidly obese, TJA patients are at a greater risk for postoperative anemia and consume more resources.
authors.affiliation: Chicago Medical School, Rosalind Franklin University, North Chicago, Illinois.
authors.forename: Zain
authors.initials: Z
authors.lastname: Sayeed
authors.affiliation: Division of Orthopaedics and Rehabilitation, Department of Surgery, Southern Illinois University School of Medicine, Springfield, Illinois.
authors.forename: Afshin A
authors.initials: AA
authors.lastname: Anoushiravani
authors.affiliation: Division of Orthopaedics and Rehabilitation, Department of Surgery, Southern Illinois University School of Medicine, Springfield, Illinois.
authors.forename: Monique C
authors.initials: MC
authors.lastname: Chambers
authors.affiliation: Division of Orthopaedics and Rehabilitation, Department of Surgery, Southern Illinois University School of Medicine, Springfield, Illinois.
authors.forename: Theodore J
authors.initials: TJ
authors.lastname: Gilbert
authors.affiliation: Center for Clinical Research, Southern Illinois University School of Medicine, Springfield, Illinois.
authors.forename: Steven L
authors.initials: SL
authors.lastname: Scaife
authors.affiliation: Division of Orthopaedics and Rehabilitation, Department of Surgery, Southern Illinois University School of Medicine, Springfield, Illinois.
authors.forename: Mouhanad M
authors.initials: MM
authors.lastname: El-Othmani
authors.affiliation: Orthopaedic Education Inc., Springfield, Illinois.
authors.forename: Khaled J
authors.initials: KJ
authors.lastname: Saleh
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000740:Anemia / Q000209:etiology; D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects*; D019645:Arthroplasty, Replacement, Knee / Q000009:adverse effects*; D005260:Female; D006295:Health Resources / Q000706:statistics & numerical data*; D006761:Hospitals; D006801:Humans; D007902:Length of Stay; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009767:Obesity, Morbid / Q000150:complications*; D016017:Odds Ratio; D010351:Patient Discharge; D011183:Postoperative Complications / Q000209:etiology*; D012189:Retrospective Studies; D013851:Thinness / Q000150:complications*; D020246:Venous Thrombosis / Q000209:etiology; D055815:Young Adult
keywords: body mass index; morbidly obese; nutritional status; resource consumption; total joint arthroplasty; underweight