Background: Discharge from the hospital on the day of (same-day) hip and knee arthroplasties has become more common; however, to our knowledge, few studies have compared morbidity between same-day and inpatient surgical procedures. The aims of this study were to compare matched cohorts of patients who underwent same-day and inpatient hip or knee arthroplasty in terms of postoperative complications and 30-day readmission rates.
Methods: Patients who underwent primary elective total hip arthroplasty, total knee arthroplasty, or unicompartmental knee arthroplasty from 2005 to 2014 were identified from the National Surgical Quality Improvement Program registry. Patients discharged the day of the surgical procedure were matched 1:1 with patients who had an inpatient stay using propensity scores. The rates of 30-day adverse events and readmission were compared between matched cohorts using the McNemar test. Risk factors for 30-day readmission following same-day procedures were identified using multivariate regression.
Results: Of 177,818 patients identified, 1,236 (0.70%) underwent a same-day surgical procedure. After matching, there were no differences in overall adverse events or readmission between same-day and inpatient groups, although inpatients had increased thromboembolic events (p = 0.048) and same-day patients had an increased rate of return to the operating room (p = 0.016). When procedures were assessed individually, the only difference identified was that the same-day total knee arthroplasty cohort had an increased return to the operating room compared with the inpatient total knee arthroplasty cohort (p = 0.046). Body mass index of ≥35 kg/m2 (p = 0.035), insulin-dependent diabetes (p = 0.041), non-insulin-dependent diabetes (p = 0.013), and age of ≥85 years (p = 0.039) were associated with 30-day readmission following same-day surgical procedures. Infection was the most common reason for reoperation and readmission following same-day procedures.
Conclusions: No significant differences in overall postoperative complications or readmission were found between matched cohorts of patients who underwent same-day and inpatient hip and knee arthroplasties, although inpatients had a higher rate of thromboembolic events and same-day patients had a higher rate of reoperation. Patients with a body mass index of ≥35 kg/m2, diabetes, and an age of ≥85 years had an increased risk of 30-day readmission following same-day procedures, which was most commonly due to infection.
Level of Evidence: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.