Interpreting the Hip Osteoarthritis Outcome Score Joint Replacement: Minimum clinically important difference values vary over time within the same patient population

Abstract

Introduction Total hip arthroplasty (THA) results in outstanding outcomes and long-term implant survivorship, but there continues to be a need for tools to identify surgical candidates and assist with shared decision-making. This study aims to determine the Hip Osteoarthritis Outcome Score Joint Replacement (HOOS JR) Minimum Clinical Important Difference (MCID) at two time intervals and to evaluate different methods for calculating the HOOS JR MCID for patients undergoing THA. Methods A patient reported outcome measure (PROM) database was prospectively queried at a single outpatient ambulatory surgery center for patients treated with THA between 2017 and 2018. All patients completed PROM surveys at preoperative baseline, 3-month, and 1-year follow-up. MCID was calculated at two different intervals, baseline to 3-months and baseline to 1-year, using anchoring and distribution-based methods. Anchor-based calculations were anchored to the Patient-Reported Outcomes Measure Information System (PROMIS10) quality-of-life and physical health instruments. Results 514 patients were statistically analyzed. Average HOOS JR scores were 52.5, 79.3, and 86.1 at preoperative baseline, 3-month follow-up and 1-year follow-up, respectively. The HOOS JR MCID determined by the PROMIS10 physical health anchoring method was 30.1 and 35.5 for the 3-month and 1-year time intervals. The HOOS JR MCID determined by the PROMIS10 quality-of-life anchoring method was 31.1 and 34.8 for the 3-month and 1-year time intervals. The distribution method MCID was 8.2 for the 3-month interval and 8.4 for the 1-year interval. Conclusions MCID values vary by time and by calculation method. THA patients may require individualized and time-point specific MCID formulas to better guide clinical decision-making.