Inconsistent Classification of "Outpatient" Surgeries Leads to Different Outcomes Following Total Hip Arthroplasty in...

With rising utilization of outpatient total hip arthroplasty (THA) in older patients including Medicare beneficiaries, the objective was to compare differences in definition including (1) patient demographics; (2) lengths of stay (LOS); and (3) outcomes of "outpatient" (stated status) versus "same-day discharge" (SDD) (actual LOS = 0 days) utilizing a nationwide database.

A national database from 2015 to 2019 was queried for Medicare-aged patients undergoing outpatient THA. Total outpatient THAs (N = 6,072) were defined in one of 2 ways: either "outpatient" by the hospital (N = 2,003) or LOS = 0 days (N = 4,069). Demographics, LOS, discharge destinations, and complications were compared between groups. Logistic regression models computed odds ratios (ORs) for factors leading to complications, readmissions, and nonhome discharges. P values < .008 were significant.

Women (OR: 1.19, P = .002), diabetes mellitus (OR: 1.31, P = .003), general anesthesia (OR: 1.24, P = .001), and longer operative times (≥95 minutes) (OR: 1.82, P < .001) were associated with 'outpatient' designation versus SDD. Within the hospital-defined 'outpatient' cohort, 49.1% (983 of 2,003) were discharged the same day (LOS = 0 days), and 21.8% had LOS 2 or more days. The hospital-defined 'outpatient' cohort had greater odds of nonhome discharges (6.3 versus 2.8%; OR: 1.88, P < .001) compared to SDD surgeries. The incidence was higher for any complication among hospital-defined 'outpatient' designated patients compared to SDD (5.5 versus 3.9%, P = .007).

Outpatient surgeries may be misleading and often do not correlate with SDD, as over 20% remain in the hospital 2 or more days. Investigators should quantitatively define the "outpatient" status by actual LOS to allow standardization and results comparison.

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