Length of Stay After Joint Arthroplasty is Less Than Predicted Using Two Risk Calculators

Predicting the length of stay (LOS) after total joint arthroplasty (TJA) has become more important with their recent removal from inpatient-only designation. The American College of Surgeons (ACS) National Surgical Quality Improvement Program surgical risk calculator and the CMS’ diagnosis-related group (DRG) calculator are two common LOS predictors. The aim of our study was to determine how our actual LOS compared with those predicted by both the ACS and DRG.

99 consecutive TJA (49 hips and 50 knee procedures) were reviewed in Medicare-eligible patients from four fellowship-trained arthroplasty surgeons. Predicted LOS was calculated using the DRG and ACS risk calculators for each patient using demographics, medical histories, and comorbidities. LOS was compared between the predicted and the actual LOS for both total hip arthroplasty (THA) and total knee arthroplasty (TKA) using paired t-tests.

Actual LOS was shorter in the THA group vs the TKA group (1.29 days vs 1.46 days, P < .05). The actual LOS of patients at our institution was significantly shorter than both DRG and ACS predictions for both THA and TKA (P < .05). In both the THA and TKA patients, the actual LOS (1.29 and 1.46 day) was significantly shorter than the DRG-predicted LOS (2.15 and 2.15 days) which was significantly shorter than the ACS-predicted LOS (2.9 and 3.14 days).

We found the actual LOS was significantly shorter than that predicted by both the DRG and ACS risk calculators. Current risk calculators may not be accurate for contemporary fast-track protocols and newer tools should be developed.