Readmission Rates for One Versus Two-Midnight Length of Stay for Primary Total Knee Arthroplasty

Background: The length of stay (LOS) in the hospital for total knee arthroplasty (TKA) has been declining over recent decades. The purpose of this study was to determine if patients with an LOS for TKA that includes only 1 midnight have an increased odds of 90-day readmission compared with those with a 2-midnight LOS. We also sought to identify any predictors of 90-day hospital readmission among those readmitted during our period of analysis.

Methods: A retrospective review of the Michigan Arthroplasty Registry Collaborative Quality Initiative (MARCQI) database was performed to identify patients with a 1-midnight or 2-midnight LOS for TKA during a 5-year period. The primary end point of this study was inpatient readmission within the 90-day postoperative period. A multiple logistic regression model and propensity score matching were used to compare the odds of 90-day readmission between 1-midnight and 2-midnight LOS. The secondary end points of this study were 90-day complications.

Results: There were 96,250 TKA procedures identified in the database, and 46,709 met our inclusion criteria for LOS. No difference in 90-day-readmission odds between patients with a 1-midnight LOS and those with a 2-midnight LOS for primary TKA was identified. Male sex, single marital status, age of ≥80 years, type-I diabetes, previous smoking, narcotic use prior to surgery, and a higher American Society of Anesthesiologists (ASA) scores increased the odds of 90-day readmission. Patients in the age group of ≥50 to <65 years, those with a higher preoperative hemoglobin level, and those with a positive social history of alcohol use were found to have decreased odds of readmission.

Conclusions: We found no association between the LOS for primary TKA (1 midnight compared with 2 midnights) and the 90-day readmission risk.

Level of Evidence: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.