Which TKA Patients Will Convert to Inpatient From Outpatient?

What kind of patients are more likely to convert from having their knee replacement (TKR) surgery inpatient to outpatient?

Researchers from NYU Langone Health designed and conducted a study to map the characteristics of patients who were initially slated for total knee arthroplasty (TKA) with an outpatient status, but who then converted to an inpatient status. Their work, “Patient Designation Prior to Total Knee Arthroplasty: How Can Preoperative Variables Impact Postoperative Status?” appears in the September 2023 edition of The Journal of Arthroplasty.

“As payment models change, we wanted to gain insight into which patient characteristics may influence an inpatient vs outpatient stay,” said co-author Ran Schwarzkopf, M.D. “Many authors have reported in the past about same day discharge and how to select and guide patients into this pathway. We wanted to evaluate this differently and see which patients actually stay and have an inpatient designation.”

The team retrospectively reviewed all patients who underwent a primary TKA at NYU Langone Health between January 2, 2018, and April 26, 2022. They found that of the 2,313 patients originally slated for outpatient TKA, 627 (27.1%) required a stay of two midnights or longer.

Those in the inpatient group had significantly higher facility discharge rates compared to the outpatient group. Factors predictive of conversion included age of 65 years and older, women, arriving at the post anesthesia care unit after 12:00pm, body mass index greater than 30, and Charlson Comorbidity Index of 4 and higher.

Being the first case of the day and being married were both protective against conversion.

Dr. Schwarzkopf told OTW, “I think we validated the notions we had, i.e., that older, more obese and patients with a higher comorbidity burden had a longer stay, an inpatient stay, and had a higher non-home discharge. Also, we have shown that patients that don’t live alone find it easier to go home on the day of surgery.”

As for how surgeons can use the patient-specific factors in decision-making, Dr. Schwarzkopf said, “I think in today’s environment, especially in urban settings where patients may have less social support, surgeons may need to think about preoperative education and patient engagement on when and how will the patient feel most comfortable going home after surgery.”