Clinically Relevant Threshold Achievement Evolves Over Time Following Primary Total Hip Arthroplasty.

Abstract

Patient-reported outcome thresholds add clinical relevance to functional outcome scores. This study aimed to define the patient acceptable symptom state (PASS) and minimum clinically important difference (MCID) for the modified Harris Hip Score (mHHS), visual analog scale (VAS) for pain, Hip Osteoarthritis Outcome Score for Joint Replacement (HOOS-JR), and Forgotten Joint Score (FJS) and identify differences in threshold achievement over time. Data were retrospectively reviewed for patients who underwent primary total hip arthroplasty between December 2016 and February 2020. A total of 221 hips were included and had complete two- and five-year outcomes with anchor questions for the mHHS, VAS, and HOOS-JR, as well as FJS postoperatively. Receiver operating characteristic (ROC) curves determined PASS threshold values. The MCID was determined using the distribution method for the mHHS and VAS. Rates of threshold achievement were compared between timepoints. The PASS thresholds and achievement rates at the two-year mark for the mHHS, HOOS-JR, FJS, and VAS were as follows: 88.0 (76%); 71.9 (85.5%); 53.1 (89.1%); and 2.5 (84.6%). The PASS thresholds and rates of achievement at the five-year mark for the mHHS, HOOS-JR, FJS, and VAS were as follows: 75.0 (86.4%), 60.4 (91.0%), 51.0 (86.9%), and 2.3 (83.3%). More patients achieved the PASS at the five-year compared to the two-year timepoint for the mHHS (84.6 versus 76%; P < 0.01). The MCID was achieved at similar rates over the two- and five-year time points for the mHHS (P = 0.76) and VAS (P = 0.22). Rates of achieving the PASS increased from two- to five-year follow-up. The PASS thresholds also reflected lower functional demands with time. There were no significant differences in rates of achieving the MCID. While overall function may decrease with advancing age, evidenced by lower PASS threshold scores, patient satisfaction increases over time.