RAPT Scores Predict Inpatient Versus Outpatient Status and Readmission Rates After IPO Changes for Total Joint Arthroplasty: An Analysis of 12,348 Cases

Abstract

BackgroundChanges to Medicare’s Inpatient Only List (IPO) and factors associated with the COVID pandemic have led to more total joint arthroplasty (TJA) patients to be designated as outpatient (OP). This potentially complicates postoperative care for patients with lower functional status and poor social support. These factors make the decision between OP versus inpatient (IP) designation particularly challenging for healthcare teams. The Risk Assessment and Prediction Tool (RAPT) was designed to indicate patient risk for needing posthospital discharge to facility and considers social and functional factors. The purpose of this study is to 1) evaluate the correlation of RAPT as a clinical tool to aid decision-making regarding OP versus IP for Total Hip and Knee Arthroplasty (THA and TKA), 2) assess the impact of recent changes to the IPO and the COVID pandemic on OP TJA readmission rates, and 3) determine whether 90-day readmissions are correlated with RAPT scores after OP TJA. MethodsWe identified all elective TKA and THA patients from 2015 through 2021 in our electronic health record at our large, urban, academic health system. Fracture patients were excluded. For those patients with available RAPT scores, we determined OP and IP designations, with IP defined as those with length-of-stay 2 midnights or more. We performed subanalysis of OP between same-day and next-day discharge. RAPT scores and readmission rates were compared at time points related to changes in the IPO: before TKA removal in 2018 (period A), from 2018 until THA removal in 2020 (Period B), and after January 1, 2020, inclusive of impact from the COVID pandemic (Period C). ResultsReviewed were 11,819 elective TKAs and 10,212 elective THAs. RAPT scores were available for 6,759 TKA patients and 5,589 THA patients. For both TKA and THA, RAPT scores between IP, same-day, and next-day discharged OP were significantly different across all time periods (P < .001). The percentage of OP designation increased across all time periods for TKA and THA. Over these same time periods, mean RAPT scores decreased significantly for both OP TKA and OP THA (P < .01). Concurrent with these changes were significant increases in OP THA 90-day readmission rates across Periods A and B (P = .010) as well as A and C (P = .006). Readmitted OP TKA had significantly lower RAPT scores than OP TKA without readmission during Period B (P < .001). Readmitted OP THA had significantly lower RAPT scores than those without readmission for all periods (P < .05). To facilitate clinical utility, median RAPT scores were also analyzed, and showed that RAPT scores for OP THA patients with readmission were 1 to 2 points lower for all time periods. ConclusionRAPT scores correlate with IP versus OP status for both TKA and THA and vary significantly with same-day versus next-day discharge. OP TJA RAPT scores may also help predict readmission, and counsel some patients away from OP surgery. Average RAPT scores of 10, 9, and 8 appeared to be separators for same day, next day, and inpatient stay. Changes to the IPO and COVID pandemic correlate with decrease in RAPT scores for both TKA and THA patients within all designations. In addition, a shift toward lower RAPT for OP TJA correlates with increased 90-day readmission rates for OP TJA. Taken together, these results suggest that patients with poorer function and worse social support systems are increasingly being driven toward OP surgery by these changes, which may play a role in increasing readmission rates. Social support and functional factors should be considered for OP elective TKA and THA. Further, any OP TJA value-based payment system must account for these variables.