Can Total Knee Arthroplasty Be Performed Safely as an Outpatient in the Medicare Population?

The Centers for Medicare and Medicaid Services has solicited public comments for the 2017 Proposed Rule to consider removing total knee arthroplasty (TKA) from the Inpatient Only List. The purpose of this study is to compare the complication rates between outpatient (same-day discharge), short-stay (discharge within 1 day), and inpatient TKA and to identify the ideal candidates for a short-stay or outpatient procedure.

We queried the American College of Surgeons-National Surgical Quality Improvement Program database for patients over age 65 years who underwent TKA from 2014 to 2015. Demographics, comorbidities, 30-day complications, and readmission rates were compared between patients after outpatient, short-stay, and inpatient procedures. A multivariate regression analysis was then performed to identify at-risk patients who should not be candidates for outpatient or short-stay TKA.

Of the 49,136 Medicare-aged TKA patients, 365 (0.7%) were outpatient, 3033 (6%) were short-stay and 45,738 (93%) were inpatient. Short-stay patients had a lower complication rate than both the outpatient and inpatient groups (2% vs. 8% vs. 8%, P < .001). Independent risk factors (all P < .05) for experiencing a complication or requiring an inpatient stay include female gender (odds ratio [OR] 1.655), general anesthesia (OR 1.282), diabetes mellitus (OR 1.171), chronic obstructive pulmonary disease (OR 1.579, P < .001), hypertension (OR 1.144), kidney disease (OR 1.425), American Society of Anesthesiologists Score 4 (OR 1.748), body mass index >35 kg/m² (OR 1.265), and age >75 years (OR 1.429).

TKA can be performed safely as an outpatient in a subset of healthy Medicare patients with a complication rate similar to an inpatient stay. A 23-hour stay, however, may be the "sweet spot" that minimizes complications in this population.