Clinically Relevant Thresholds in Patient-Reported Outcomes: Do Patients' Expectations Evolve Over Long-term Follow-up?

Abstract

Background: Clinically relevant thresholds have been utilized to provide insight into postoperative functional status and patient satisfaction.

Purpose: To define and evaluate the minimal clinically important difference (MCID), Patient Acceptable Symptom State (PASS), and substantial clinical benefit (SCB) thresholds over the 2-, 5-, and 10-year timepoints for the modified Harris Hip Score (mHHS), Hip Outcome Score-Sports-Specific Subscale (HOS-SSS), and International Hip Outcome Tool (iHOT12).

Study design: Case series; Level of evidence, 4.

Methods: Data were retrospectively reviewed for patients who underwent primary hip arthroscopy from 2008 to 2021. The inclusion criteria comprised complete patient-reported outcome scores with anchor questions at the 2-, 5-, or 10-year timepoints. Groups were propensity score-matched 1 to 1 to 1 for these 3 timepoints to limit confounding variables. The PASS, SCB, and MCID thresholds were defined using the anchor-based method for the mHHS, HOS-SSS, and iHOT12.

Results: A total of 414 hips were included in the study. Area under the curve for all defined thresholds indicated acceptable to excellent discrimination. The thresholds for achieving the PASS, defined at the 2-, 5-, and 10-year respectively, were as follows: mHHS: 77.5, 85.5, and 78.5; HOS-SSS: 82.7, 76.4, and 67.7; and iHOT12: 67.4, 76.9, and 62.9. The percentage of patients achieving the PASS increased from 2 to 10 years, with the highest percentage at 10 years. The threshold for achieving the SCB was defined as follows: mHHS: 95, 99, and 88; HOS-SSS: 97, 80.9, and 90.5; and iHOT12: 89.4, 94.1, and 82.5. The percentage of patients achieving the SCB increased from 2 to 10 years. The mean changes required to achieve the MCID were defined as follows: mHHS: 7, 7.1, and 7.4; HOS-SSS: 10.6, 10.7, and 11.2; and iHOT12: (9.6, 9.7, -). The MCID and the percentage of patients achieving the MCID remained constant over 2 to 10 years.

Conclusion: Patients met the MCID, PASS, and SCB thresholds at high rates over 10 years. Based on the PASS and SCB thresholds, patient expectations for function evolved. Lower expectations at long-term follow-ups may result in a higher percentage of patients meeting certain thresholds, as evidenced in the mHHS, HOS-SSS, and iHOT12 in this cohort. Understanding the evolution of patient expectations may help interpret clinically relevant thresholds in future studies.

Keywords: Patient Acceptable Symptom State; femoroacetabular impingement syndrome; hip arthroscopy; minimal clinically important difference; patient expectations; substantial clinical benefit.