title: Effect of i.v. acetaminophen on total hip or knee replacement surgery: a case-matched evaluation of a national patient database.
abstract: OBJECTIVE
  The effects of i.v. acetaminophen on adverse events, hospital length of stay (LOS), and overall hospital costs for total hip or knee replacements were evaluated.
  
  
  METHODS
  We conducted a matched-pairs analysis of adult inpatients who underwent elective total hip arthroplasty or total knee arthroplasty in hospitals participating in the Premier Healthcare Alliance from January 1, 2011, to November 30, 2012. Each case who received i.v. acetaminophen on the day of surgery was matched to a control who did not receive i.v. acetaminophen within the same hospital. Treatment groups were analyzed for differences in the rate of adverse effects, LOS, and hospital resource utilization.
  
  
  RESULTS
  A total of 22,146 cases and controls were similar in terms of age, race, sex, marital status, insurance status, and preoperative comorbidities. Overall adverse events were significantly lower with i.v. acetaminophen (24.3%) than with controls (26.3%, p < 0.001), numerically less frequent in all subgroups, and significantly less frequent for renal, infectious, and miscellaneous adverse events (all p < 0.05). I.V. acetaminophen was also associated with a shorter LOS, with 1 out of 11 patients discharged one day earlier (p < 0.001) and lower average hospital costs: $16,381 for cases compared with $16,927 for controls (p < 0.001). Cost savings estimated by structural equation modeling of $547 per patient were due to $325 from direct effects and $222 from indirect effects, the latter mediated through adverse events and reduced LOS.
  
  
  CONCLUSIONS
  In this retrospective cohort study of case-matched patients who underwent total hip or knee replacement surgery, multimodal analgesia with i.v. acetaminophen was associated with improved clinical outcomes in terms of fewer adverse events, shortened LOS, and reduced total hospital resources compared with patients who did not receive i.v. acetaminophen.
authors.affiliation: Christian Apfel, M.D., Ph.D., M.B.A., is Adjunct Associate Professor, Department of Epidemiology and Biostatistics, University of California, San Francisco, San Francisco. Jonathan R. Jahr, M.D., is Professor of Clinical Anesthesiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles. Colleen L. Kelly, Ph.D., is President, Kelly Statistical Consulting, San Diego, CA. Robert Y. Ang, M.D., is Senior Vice President of Business Development, Bavarian Nordic, Mountain View, CA. Gary M. Oderda, Pharm.D., M.P.H., is Professor and Director, Pharmaceutical Outcomes Research Center, University of Utah College of Pharmacy, Salt Lake City. christian.apfel@ucsf.edu.
authors.forename: Christian
authors.initials: C
authors.lastname: Apfel
authors.affiliation: Christian Apfel, M.D., Ph.D., M.B.A., is Adjunct Associate Professor, Department of Epidemiology and Biostatistics, University of California, San Francisco, San Francisco. Jonathan R. Jahr, M.D., is Professor of Clinical Anesthesiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles. Colleen L. Kelly, Ph.D., is President, Kelly Statistical Consulting, San Diego, CA. Robert Y. Ang, M.D., is Senior Vice President of Business Development, Bavarian Nordic, Mountain View, CA. Gary M. Oderda, Pharm.D., M.P.H., is Professor and Director, Pharmaceutical Outcomes Research Center, University of Utah College of Pharmacy, Salt Lake City.
authors.forename: Jonathan R
authors.initials: JR
authors.lastname: Jahr
authors.affiliation: Christian Apfel, M.D., Ph.D., M.B.A., is Adjunct Associate Professor, Department of Epidemiology and Biostatistics, University of California, San Francisco, San Francisco. Jonathan R. Jahr, M.D., is Professor of Clinical Anesthesiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles. Colleen L. Kelly, Ph.D., is President, Kelly Statistical Consulting, San Diego, CA. Robert Y. Ang, M.D., is Senior Vice President of Business Development, Bavarian Nordic, Mountain View, CA. Gary M. Oderda, Pharm.D., M.P.H., is Professor and Director, Pharmaceutical Outcomes Research Center, University of Utah College of Pharmacy, Salt Lake City.
authors.forename: Colleen L
authors.initials: CL
authors.lastname: Kelly
authors.affiliation: Christian Apfel, M.D., Ph.D., M.B.A., is Adjunct Associate Professor, Department of Epidemiology and Biostatistics, University of California, San Francisco, San Francisco. Jonathan R. Jahr, M.D., is Professor of Clinical Anesthesiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles. Colleen L. Kelly, Ph.D., is President, Kelly Statistical Consulting, San Diego, CA. Robert Y. Ang, M.D., is Senior Vice President of Business Development, Bavarian Nordic, Mountain View, CA. Gary M. Oderda, Pharm.D., M.P.H., is Professor and Director, Pharmaceutical Outcomes Research Center, University of Utah College of Pharmacy, Salt Lake City.
authors.forename: Robert Y
authors.initials: RY
authors.lastname: Ang
authors.affiliation: Christian Apfel, M.D., Ph.D., M.B.A., is Adjunct Associate Professor, Department of Epidemiology and Biostatistics, University of California, San Francisco, San Francisco. Jonathan R. Jahr, M.D., is Professor of Clinical Anesthesiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles. Colleen L. Kelly, Ph.D., is President, Kelly Statistical Consulting, San Diego, CA. Robert Y. Ang, M.D., is Senior Vice President of Business Development, Bavarian Nordic, Mountain View, CA. Gary M. Oderda, Pharm.D., M.P.H., is Professor and Director, Pharmaceutical Outcomes Research Center, University of Utah College of Pharmacy, Salt Lake City.
authors.forename: Gary M
authors.initials: GM
authors.lastname: Oderda
mesh_terms: D000082:Acetaminophen / Q000008:administration & dosage*; D061605:Administration, Intravenous; D000328:Adult; D018712:Analgesics, Non-Narcotic / Q000008:administration & dosage; D019644:Arthroplasty, Replacement, Hip / Q000191:economics / Q000379:methods*; D019645:Arthroplasty, Replacement, Knee / Q000191:economics / Q000379:methods*; D015331:Cohort Studies; D017046:Cost Savings; D005260:Female; D017721:Hospital Costs / Q000706:statistics & numerical data; D006760:Hospitalization / Q000191:economics / Q000706:statistics & numerical data; D006801:Humans; D007902:Length of Stay / Q000706:statistics & numerical data; D008297:Male; D016555:Matched-Pair Analysis; D010149:Postoperative Pain / Q000188:drug therapy*; D011183:Postoperative Complications / Q000453:epidemiology; D012189:Retrospective Studies; D016896:Treatment Outcome
chemical_list: D018712:Analgesics, Non-Narcotic; D000082:Acetaminophen