FLOOR AND CEILING EFFECTS OF THE IHOT-12 IN PATIENTS UNDERGOING HIP PRESERVATION SURGERY: A NATIONAL REGISTRY STUDY

Hip preservation surgery is a growing field, and validated patient-reported outcome measures (PROMs) play a crucial role in assessing the outcome of any intervention. This study aims to evaluate the floor and ceiling effects, which indicate data capture limitations, of the International Hip Outcome Tool-12 (iHOT-12) in patients undergoing hip preservation surgery. Data from the UK's Non-Arthroplasty Hip Registry (NAHR) were analysed. Patient demographics, surgical details, and iHOT-12 scores were collected. Floor and ceiling effects were assessed using three definitions: absolute minimum or maximum scores, scores within 10% of the minimum or maximum, and scores within one minimal clinically important difference (MCID) of the minimum or maximum. Analyses were performed for patients undergoing hip arthroscopy and periacetabular osteotomy (PAO), as well as for male and female subgroups and by iHOT-12 domain. A total of 8,408 patients (7,081 hip arthroscopy, 1,327 PAO) were included. At 26 to 52 weeks, a ceiling effect was observed in 15–22% of patients, indicating limited data capture. A floor effect was present in 9–15% of patients at baseline indicating possible limited data capture in pre-operative patients. Male and female patients had similar ceiling effects at 52 weeks, but females exhibited a higher risk of a floor effect at baseline. The sport and recreational domain was most susceptible to floor effects at baseline, and the job-related concerns domain was most susceptible to ceiling effects at follow-up. The study demonstrates the presence of floor and ceiling effects in the iHOT-12 for patients undergoing hip preservation surgery. The floor and ceiling effects were similar between patients undergoing hip arthroscopy or PAO. The study also suggests that some patients may experience greater improvement than reflected in post-operative iHOT-12 scores. The findings emphasize the need to refine outcome measurement tools to capture the full range of disease severity and post-operative improvement. Future research should focus on identifying patients at risk of floor and ceiling effects and explore modifications to PROMs to enhance their accuracy and utility.