What Are the Risk Factors for 48 or More–Hour Stay and Nonhome Discharge After Total Knee Arthroplasty? Results From 151 Illinois Hospitals, 2016-2018

Bundled payment programs and the Centers for Medicare and Medicaid Services removal of total knee arthroplasty (TKA) from the inpatient-only list potentially incentivize avoiding patients with extended length of stay (eLOS) and nonhome discharge (NHD). We aimed to describe which patients are most at risk of eLOS (>2 days), very eLOS (veLOS; >4 days), and NHD. Admissions for unilateral TKAs at 151 Illinois nonfederal hospitals from January 2016 to June 2018 were selected from the Illinois Hospital and Health Systems Association COMPdata administrative hospital discharge database. Records included patient age, race and ethnicity, Illinois region, insurance status, principal diagnosis, and date of procedure. Zip code level median household income, Charlson comorbidity index, and obesity status were computed. Hospitals were characterized through their bundled payment participation status, academic status, and annual knee replacement volume. Poisson regression was used to test the associations between patient and hospital characteristics and the likelihood of eLOS, veLOS, and NHD. Of the 72,359 admissions included, 25.0% had an NHD, 41.1% had eLOS, and 4.0% veLOS. Female patients, those 75 years old or more as compared to those 65-74 years old, non-Hispanic blacks, Hispanics and Asians versus non-Hispanic whites, Medicaid/uninsured patients versus those privately insured, obese patients, those with nonzero Charlson comorbidity index, and those treated at low-volume hospitals (600 TKAs/year) were more likely to have eLOS, veLOS, and/or NHD (P < .05). Arthroplasty surgeons may be incentivized to avoid the abovementioned patient groups due to bundled payment programs and recent Centers for Medicare and Medicaid Services legislation. •Low total knee arthroplasty hospital volume was associated with long length of stay.•Non-Hispanic black ethnicity was associated with long length of stay.•Age greater than 75 was associated with long length of stay and nonhome discharge.•Charlson Index of 3+ was associated with long length of stay and nonhome discharge.•Bundled payment hospitals were associated with length of stay greater than 4 days.