title: Does "6-Clicks" Day 1 Postoperative Mobility Score Predict Discharge Disposition After Total Hip and Knee Arthroplasties?
abstract: The use of inpatient rehabilitation services after total joint arthroplasty (TJA) is an important driver of episode-of-care costs. We determined the utility of a new standardized instrument collected during the immediate postoperative period, the Activity Measure for Post-Acute Care (AM-PAC) "6-Clicks" Mobility score, in predicting discharge disposition after TJA and its accuracy in estimating prolonged hospital stay, readmissions, and emergency department (ED) visits.
  
  
  
  Using our institutional database, we retrospectively reviewed 744 patients undergoing primary total hip (40%) or knee (60%) arthroplasty for osteoarthritis during 2014. The AM-PAC Mobility score was prospectively collected by physical therapists within 24 hours of surgery. We constructed 2 multivariable logistic regression models for each study outcome: (1) a base model containing age, sex, Charlson Comorbidity Index, and procedure type and (2) the AM-PAC model including the aforementioned variables and this score. The predictive performance of these models was assessed and compared using the area under the receiver operating characteristic (AUC) curve.
  
  
  
  The AM-PAC model provided better prediction of discharge disposition (AUC = 0.777) than the base model (AUC = 0.716; 22% relative improvement). Although the AM-PAC model performed 32% and 27% better than the base model in estimating prolonged hospital stay and ED visits, the model's predictive performance was poor (prolonged stay: AUC = 0.639; ED visit: AUC = 0.658). The AM-PAC model also showed poor discrimination of readmissions (AUC = 0.657), and there was no relative improvement in predictive performance compared to that of the base model.
  
  
  
  The AM-PAC "6-Clicks" Mobility score is a valid, simple tool for predicting discharge disposition after TJA.
authors.affiliation: Department of Orthopaedic Surgery, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts.
authors.forename: Mariano E
authors.initials: ME
authors.lastname: Menendez
authors.affiliation: Department of Orthopaedic Surgery, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts.
authors.forename: Charles S
authors.initials: CS
authors.lastname: Schumacher
authors.affiliation: Department of Orthopaedic Surgery, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts.
authors.forename: David
authors.initials: D
authors.lastname: Ring
authors.affiliation: Department of Orthopaedic Surgery, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts.
authors.forename: Andrew A
authors.initials: AA
authors.lastname: Freiberg
authors.affiliation: Department of Orthopaedic Surgery, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts.
authors.forename: Harry E
authors.initials: HE
authors.lastname: Rubash
authors.affiliation: Department of Orthopaedic Surgery, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts.
authors.forename: Young-Min
authors.initials: YM
authors.lastname: Kwon
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019644:Arthroplasty, Replacement, Hip / Q000534:rehabilitation*; D019645:Arthroplasty, Replacement, Knee / Q000534:rehabilitation*; D004185:Disability Evaluation; D005260:Female; D006801:Humans; D007297:Inpatients; D007902:Length of Stay; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D010351:Patient Discharge; D011184:Postoperative Period; D012372:ROC Curve; D020127:Recovery of Function; D012189:Retrospective Studies; D019467:Subacute Care; D055815:Young Adult
keywords: AM-PAC; discharge; mobility; resource utilization; total hip arthroplasty; total knee arthroplasty