Same Day Knee Arthroplasty Doubled in 2018

On January 1, 2018, the Centers for Medicare & Medicaid Services (CMS) knocked total knee arthroplasty (TKA) off the “inpatient-only” list. Over the ensuing 12 months, same-day discharges for total knee arthroplasty doubled.

That’s one of the many conclusions from a Yale Department of Orthopedics and Rehabilitation study titled “Centers for Medicare & Medicaid Services’ 2018 Removal of Total Knee Arthroplasty From the Inpatient-only List Led to Broad Changes in Hospital Length of Stays,” and published in the December 15, 2021, edition of the Journal of the American Academy of Orthopaedic Surgeons.

Co-author Kelsey Rankin, an M.D. Candidate at the Yale School of Medicine, explained the rationale for the study to OTW, “We believe this was an imperative time for this study. With the release of the most recent data on total knee arthroplasty through the National Surgical Quality Improvement Program, we were able to see how a policy change—specifically the removal of total knee arthroplasty from the inpatient-only list—directly affected patient care. This allows us to understand, with relative immediacy, how policy changes impact patients on the ground.”

The researchers identified 125,613 TKA patients from 2017 to 2018 (232,269 patients from 2015 to 2018). Being at least 65 years old, most of these individuals were eligible for Medicare (60.78% in 2017 and 62.42% in 2018).

“Overall,” wrote the authors, “Length of stay [LOS] decreased significantly from 2017 to 2018 and more patients were discharged the same day (5.09% versus 2.28%).

In 2017, patients were coded as “outpatient” 1.66% of the time (those with length of stay = 0 days were 22.85%, LOS = 1 day were 1.80%, length of stay = 2 days were 0.79%, and length of stay ≥ 3 days were 0.85%).

In 2018, patients were coded as “outpatient” 17.14% of the time (those with length of stay = 0 days were 78.2%, length of stay = 1 day were 29.75%, length of stay = 2 days were 6.96%, and length of stay ≥ 3 days were 3.05%).

“This represented a significant change for each length of stay day. These results remained true when stratifying by Medicare eligibility.”

“Our most important results include the fact that more patients were discharged on the day of surgery in 2018 compared with 2017 (before and after the policy change that removed total knee arthroplasty from the inpatient-only list), length of stay decreased between 2017 and 2018, and that more patients were coded as outpatients in 2018 compared with 2017, reflecting direct changes in policy on hospital coding as well as patient care.”

Asked how this affected patient care, Rankin told OTW, “This has directly impacted patient care, specifically, how long patients are staying in the hospital. As we see it, patients are now more likely to be discharged on the day of surgery, as they are now more likely to be coded as outpatients instead of inpatients. This is having a direct cost on patients and hospital systems.”