OBJECTIVES: Prior studies have identified baseline function and comorbidities as predictors of total hip arthroplasty (THA) outcomes. However, most studies evaluate joint-specific, rather than general health outcomes such as PROMIS-Physical Function (PF). The purpose of this study was to evaluate patient characteristics and postoperative events associated with minimal clinically important difference (MCID) achievement after THA using PROMIS-PF.

METHODS: A retrospective review of 274 patients undergoing THA with preoperative and 1-year postoperative PROMIS-PF scores from March 2020 to January 2022 was performed. Three multivariate models were built to evaluate predictors of MCID achievement. Predictors evaluated included preoperative factors (demographics, comorbidities, surgical history, baseline PROMIS-PF), postoperative clinical outcomes (length of stay, discharge status, 90-day ED returns/readmissions, 1-year complications), and utilization of other orthopedic services over 1-year postoperatively.

RESULTS: 152 patients (55%) achieved MCID at 1-year postoperatively. In the preoperative model, only baseline PROMIS-PF score was predictive of MCID (37.98 ± 6.12 vs. 35.06 ± 5.52: p<0.001), with each 1-point increase in PROMIS-PF decreasing odds of MCID achievement by 11% (OR: 0.89, 95% CI: 0.84 to 0.93; p<0.001). None of the clinical outcomes assessed were independently predictive of MCID achievement. During the 1-year postoperative period, 73% of patients sought care for another orthopedic condition. Patients seeking care for any other orthopedic condition were 2.5 times less likely to achieve MCID (OR: 0.40, 95 % CI:0.17 to 0.93; p=0.034), and those seen for a spine condition were 1.85 times less likely to achieve MCID (OR: 0.54, 95 % CI: 0.29 to 0.99; p=0.028).

CONCLUSIONS: Predictors for failure to achieve MCID after THA were higher baseline PROMIS-PF, postoperative treatment for another orthopedic condition, and postoperative care for a spine condition. Although general PROMs such as PROMIS-PF are useful in assessing THA outcomes, these results highlight that coexistent orthopedic conditions may confound results.