Utility of the LET-IN-OUT Clinical Decision Support Tool for Medical Risk Stratification Prior to Outpatient Total Hip or Knee Arthroplasty

Abstract

Background: Musculoskeletal care teams can benefit from simple, standardized, and reliable preoperative tools for assessing discharge disposition after total joint arthroplasty. Our objective was to compare the predictive strength of the Ascension Seton Lower Extremity Inpatient-Outpatient (LET-IN-OUT) tool versus the American Society of Anesthesiologists Physical Status (ASA-PS) score for predicting early postoperative discharge.

Methods: We retrospectively extracted sociodemographic, surgical admission, postoperative day (POD) of discharge, 90-day readmissions, and predictions of the LET-IN-OUT and ASA-PS tools from the electronic records of 563 consecutive hip or knee arthroplasty patients (mean age 65 [SD 9.6], 54% women). Included patients who underwent a total hip arthroplasty (THA) or total knee arthroplasty (TKA) at a single health system between June 2020 and March 2021. We performed descriptive statistics and analyzed predictive values of each tool, defining "early discharge" primarily as discharge before the second postoperative day (POD 2), and secondarily as before 24 hours, and on the same calendar day (POD 0) as surgery.

Results: The LET-IN-OUT tool demonstrated superior predictive power among hip and knee arthroplasty patients compared to the ASA-PS tool for discharge prior to POD 2 (positive predictive value [PPV] 89 versus 83%, positive likelihood ratio [+LR] 2.0 versus 1.2), discharge before 24 hours (PPV 86 versus 70%, +LR 2.9 versus 1.2), and discharge on POD 0 (PPV 34% versus 30%, +LR 1.2 versus 1.1).

Conclusions: The Ascension Seton Lower Extremity Inpatient-Outpatient tool predicted patients suitable for early discharge following THA or TKA and did so more effectively than the ASA-PS score.

Keywords: medical risk stratification; outpatient surgery; same-day discharge; total joint arthroplasty; two-midnight rule.