FP16.5 An Investigation of Response Shift Bias and Coping Styles Following Hip Arthroscopy

Abstract ICLA16 - Beyond the Operating Room: Value-Based Healthcare, Large Registries, and Predicting Failures, Auditorium B (BMCC Level 1), October 9, 2026, 14:00 - 16:00 Background Patient-reported outcome measures (PROMs) are increasingly used to assess surgical success following hip arthroscopy for femoroacetabular impingement (FAI). However, response shift, defined as changes in patients' internal standards or perceptions over time, may bias longitudinal PROM evaluations. Objective This study aimed to determine whether a clinically meaningful response shift occurs one and two years after hip arthroscopy for FAI, and to examine whether coping strategies, life events, or clinical factors predict response shift or post-operative PROMs. Methods A prospective cohort of 105 patients undergoing first time hip arthroscopy for unilateral symptomatic FAI completed the International Hip Outcome Tool-12 (iHOT-12) and Hip Outcome Score (HOS-ADL and HOS-Sport) pre-operatively (pre-op) and at one and two years post-operation (post-op). At follow-up, participants were also asked to think back and rate how they remembered feeling before surgery, allowing comparison between their original and recalled pre-op ratings. Additionally, at the post-op time points participants completed the Brief-COPE and reported any major life events since baseline. Response shift was quantified using the then-test method and classified as meaningful positive (recalled pre-op health worse than initially reported) or meaningful negative (recalled health better than initially reported). Regression analyses examined associations of coping style, life events, adverse events, age, and lifestyle changes with post-operative PROMs and response shift magnitude. Results PROMs improved significantly from baseline to follow-up across all measures (p<0.001). Meaningful response shift was common: HOS-ADL (1yr: 49%, 2yr: 49%) HOS-Sport (1yr: 66%, 2yr: 56%), and iHOT-12 (1yr: 61%, 2yr: 47%). Most participants demonstrated positive shifts for HOS-ADL, HOS-Sport, and iHOT-12 at both one and two years post-op. At one year, effect sizes using original pre-op scores were large (Cohen’s d=1.47-1.48), but smaller when recalled scores were used (d=1.29-1.47). However, at two years post-op, the effect sizes increased when recalled pre-op scores were used (pre-op d=1.51-2.19 vs. recalled d=1.66-2.27). Suggesting an overestimated treatment effect at one year post-op when using original pre-op scores, but at an underestimated treatment effect at two years post-op. Positive coping and magnitude of lifestyle change (number and significance of life events) were predictive of response shift magnitude at one year post-op. No significant predictors were identified at two years post-op. Conclusions Clinically meaningful response shift was observed in most patients after hip arthroscopy, increasing the perceived magnitude of improvement. PROMs should be interpreted cautiously over time, as evolving perceptions and coping factors may influence reported recovery.