Minimal important changes and differences were estimated for Oxford hip and knee scores following primary and revision arthroplasty

Objectives: To create estimates for clinically meaningful changes and differences in pain and joint function for the Oxford Hip and Knee Scores (OHS/OKS) in primary and revision joint replacement. Study Design and Setting: 694,487 primary and revision joint replacement procedures were analyzed from the NHS PROMs dataset between 2012-2020 Minimal important changes (MIC) and differences (MID) were calculated using distribution and anchor-based methods (including receiver-operating characteristic (ROC) curve and predictive-modelling techniques). Results: For comparison of two or more groups (such as in a clinic trial), MID estimates were similar to 5 points. For cohort studies investigating changes over time in a single group of patients, M/C-group estimates were 12.4 points (primary hip replacement), 8.6 points (revision hip replacement), 10.5 points (primary knee replacement) and 9.4 points (revision knee replacement). For studies investigating changes over time at the individual patient level, MICadjusted estimates were similar to 8 points, similar to 6 points, similar to 7 points and similar to 6 points respectively. Conclusion: This study has calculated contemporary estimates of clinically important changes and differences for the OHS/OKS for primary and revision hip and knee replacement. These estimates can be used to inform sample size calculations and to interpret changes in joint function over time and differences between groups. (C) 2021 The Author(s). Published by Elsevier Inc.

Automated summary

This study estimated the clinically meaningful changes and differences for the Oxford Hip and Knee Scores (OHS/OKS) using distribution and anchor-based methods. The estimates can be used for sample size calculations and interpreting changes in joint function and differences between groups.