# The Effects of Comorbidities on Outcomes After Total Hip Replacement

## TL;DR

Patients with higher comorbidity levels (ASA 3) had slower recovery after hip replacement but still achieved good outcomes, suggesting surgery should not be avoided based on comorbidities alone.

## Contribution

This study demonstrates that higher ASA classification independently predicts poorer 6-month outcomes after THR, despite similar long-term recovery potential.

## Key findings

- ASA 3 patients had lower preoperative scores and longer hospital stays compared to ASA 1–2 patients.
- Higher ASA grade remained an independent negative predictor of 6-month Oxford Hip Score.
- Both groups achieved excellent functional outcomes at 6 months post-surgery.

## Abstract

Background: The relationship between comorbidity burden, as measured by the American Society of Anesthesiologists (ASA) classification, and functional recovery after total hip replacement (THR) remains uncertain. This study aimed to clarify whether ASA grade independently predicts postoperative patient-reported outcomes. Methods: We conducted a retrospective analysis of 218 consecutive patients from a prospectively maintained institutional registry who underwent primary unilateral THR between March 2021 and March 2024 in a single center. Patients were stratified into ASA 1–2 and ASA 3 groups. The Oxford Hip Score (OHS, 0–48) was collected preoperatively and at 1 week, 3 months, and 6 months postoperatively. Between-group differences were assessed, and multivariable linear regression was used to identify predictors of 6-month OHS. Results: Compared with ASA 1–2 patients, ASA 3 patients had lower preoperative OHS and longer hospital stay, but both groups showed substantial improvement over time and achieved excellent mean OHS at 6 months. In the adjusted model, higher ASA grade remained an independent negative predictor of 6-month OHS, whereas higher preoperative OHS and BMI were positive predictors. Conclusions: Despite presenting with worse baseline function and requiring longer hospitalization, ASA 3 patients experienced clinically meaningful recovery and achieved favorable 6-month outcomes after THR. Higher ASA status should therefore inform perioperative optimization rather than preclude surgery.