What Triggers Inpatient Stays for Medicare TKAs?

Seeking to dig into the feasibility and wisdom of outpatient TKA in Medicare-aged patients a team from the University of Connecticut undertook a study titled, “Predicting Inpatient Status After Primary Total Knee Arthroplasty in Medicare-Aged Patients.”

Their work was published in the July 2019 edition of The Journal of Arthroplasty.

Mohamad Halawi, M.D., assistant professor of orthopedic surgery at the University of Connecticut and study co-author explained how recent CMS changes prompted him and his team to look closely at total knee arthroplasty in Medicare-aged patients, “Starting January 1, 2018, the Centers for Medicare and Medicaid Services (CMS) removed total knee arthroplasty (TKA) from its inpatient-only list.”

“This move has created significant confusion among surgeons and hospitals due to limited information on the selection criteria for outpatient vs. inpatient surgery in this patient population. As a result, arthroplasty surgeons have come under increased pressure by regulatory entities to default to outpatient status for most TKAs despite lack of evidence to support this practice.”

For the study, Dr. Halawi and his colleagues looked at Medicare patients undergoing a total knee arthroplasty between 2006 and 2015.

Dr. Halawi explained the methodology of the study OTW, “Using a large national database, we identified a number of patient characteristics that are associated with a hospital length of stay (LOS) exceeding two midnights—this is the time benchmark established by CMS to qualify for inpatient status. A simple, internally validated predictive nomogram was constructed based on those patient characteristics.”

The authors tallied up data from 61,284 inpatient admissions and 26,066 outpatient admissions. The greatest determinants of an inpatient stay were:

• The age of the patients was >80
• the procedures performed was a simultaneous bilateral TKA
• dependent functional status
• metastatic cancer
• female gender

“It’s important to note” said Dr. Halawi, “that 70% of patients analyzed in our study had hospital stay greater than two midnights. This indicates that while outpatient TKA is feasible in Medicare-aged patients, it is certainly not the standard. This should be taken into consideration by surgeons, hospital administrators, and regulatory bodies.”

“Until we have well-accepted selection criteria, arthroplasty surgeons not experienced with outpatient total knee arthroplasty should not be pressured to default to outpatient admission in Medicare patients.”