Risk Factors of Failure to Discharge Before "Two Midnights" in Outpatient-Designated Total Hip Arthroplasty

Area of Science:

• Orthopedic Surgery
• Health Services Research

Background:

• Centers for Medicare and Medicaid Services removed total hip arthroplasty (THA) from inpatient-only status.
• Outpatient THA admissions can still require extended hospitalization if they span two midnights.
• This complicates care coordination and reimbursement for patients needing longer stays.

Purpose of the Study:

• To evaluate risk factors associated with extended length of stay (LOS) of 2 days or more for outpatient-designated THA.
• To identify patient characteristics that predict longer hospitalizations after THA.

Main Methods:

• Analysis of 17,063 outpatient THA procedures from the National Surgical Quality Improvement Program database (2015-2020).
• Stratification of patients into groups with LOS < 2 days and LOS ≥ 2 days.
• Comparison of demographics, comorbidities, and outcomes using univariate and multivariable regression analyses.

Main Results:

• Patients with LOS ≥ 2 days were older, more likely to have a BMI > 35, and had higher incidences of smoking, diabetes, COPD, and hypertension.
• Extended LOS was associated with increased rates of surgical site infection, hospital readmission, and revision surgery within 30 days.
• Independent risk factors for extended LOS included advanced age, female sex, African American race, Hispanic ethnicity, diabetes, smoking, and hypertension.

Conclusions:

• A significant subset of outpatient THA patients face the risk of extended hospital stays, even after policy changes.
• Understanding these risk factors allows surgeons to proactively identify at-risk patients.
• Early identification enables better care planning and facilitates timely inpatient preauthorization when necessary.