Weighted predictive modelling estimation of patient acceptable symptom state for forgotten joint score, Oxford hip score, and EuroQol health index 3 and 12 months after total hip arthroplasty in a United Kingdom cohort

PURPOSE: Patient acceptable symptom state (PASS) enhances interpretation of patient-reported outcome measures (PROMs). However, very few studies have defined PASS values for widely used PROMs and are based on methods sensitive to distribution of PROM scores or weak correlation. This study utilises a new anchor-based method to estimate PASS thresholds for Forgotten Joint Score (FJS), Oxford Hip Score (OHS) and EuroQol health index (EQ-5D-5L) at 3 and 12 months after primary total hip arthroplasty (PTHA). METHODS: This retrospective cohort study used data for PTHAs performed at a high-volume arthroplasty centre in Scotland between April 2021 and March 2023. PROMs were FJS, OHS and EQ-5D-5L. A new weighted predictive modelling method was used to define PASS values. Anchor questions used were surgery-specific satisfaction for the FJS and OHS, and EQ-Visual Analogue Scale for the EQ-5D-5L. RESULTS: A total of 2793 PTHAs were performed, of which 65 to 73% had complete PROMs data. Respective median age and BMI were 69 years and 29.1 kg/m² and 57% were female. The Spearman correlations between anchors and PROMs ranged between 0.35 and 0.54. PASS thresholds (95% CI) at 3 and 12 months respectively were 31.5 (29.5–33.9) and 38.3 (36.5–42.4) for FJS, 31.5 (29.1–32.8) and 36.2 (35.1–36.8) for OHS, 0.814 (0.795–0.822) and 0.867 (0.845–0.875) for EQ-5D-5L. CONCLUSION: We report new PASS thresholds for FJS, OHS and EQ-5D-5L 3 and 12 months following PTHA. These thresholds reflect the symptom (health) state at which an average Scottish patient considers their outcome acceptable.