Mapping analysis to predict the associated EuroQol five-dimension three-level utility values from the Oxford Knee Score : a prediction and validation study

Nick D Clement; Irrum Afzal; Christian J H Peacock; Deborah MacDonald; Gavin J Macpherson; James T Patton; Vipin Asopa; David H Sochart; Deiary F Kader

doi:10.1302/2633-1462.37.BJO-2022-0054.R1

Mapping analysis to predict the associated EuroQol five-dimension three-level utility values from the Oxford Knee Score : a prediction and validation study

Bone Jt Open. 2022 Jul;3(7):573-581. doi: 10.1302/2633-1462.37.BJO-2022-0054.R1.

Authors

Affiliations

¹ South West London Elective Orthopaedic Centre, Epsom, UK.
² Edinburgh Orthopaedics, Royal Infirmary of Edinburgh, Edinburgh, UK.
³ Department of Orthopaedics, University of Edinburgh, Edinburgh, UK.

PMID: 35837809
PMCID: PMC9350693
DOI: 10.1302/2633-1462.37.BJO-2022-0054.R1

Abstract

Aims: The aims of this study were to assess mapping models to predict the three-level version of EuroQoL five-dimension utility index (EQ-5D-3L) from the Oxford Knee Score (OKS) and validate these before and after total knee arthroplasty (TKA).

Methods: A retrospective cohort of 5,857 patients was used to create the prediction models, and a second cohort of 721 patients from a different centre was used to validate the models, all of whom underwent TKA. Patient characteristics, BMI, OKS, and EQ-5D-3L were collected preoperatively and one year postoperatively. Generalized linear regression was used to formulate the prediction models.

Results: There were significant correlations between the OKS and EQ-5D-3L preoperatively (r = 0.68; p < 0.001) and postoperatively (r = 0.77; p < 0.001) and for the change in the scores (r = 0.61; p < 0.001). Three different models (preoperative, postoperative, and change) were created. There were no significant differences between the actual and predicted mean EQ-5D-3L utilities at any timepoint or for change in the scores (p > 0.090) in the validation cohort. There was a significant correlation between the actual and predicted EQ-5D-3L utilities preoperatively (r = 0.63; p < 0.001) and postoperatively (r = 0.77; p < 0.001) and for the change in the scores (r = 0.56; p < 0.001). Bland-Altman plots demonstrated that a lower utility was overestimated, and higher utility was underestimated. The individual predicted EQ-5D-3L that was within ± 0.05 and ± 0.010 (minimal clinically important difference (MCID)) of the actual EQ-5D-3L varied between 13% to 35% and 26% to 64%, respectively, according to timepoint assessed and change in the scores, but was not significantly different between the modelling and validation cohorts (p ≥ 0.148).

Conclusion: The OKS can be used to estimate EQ-5D-3L. Predicted individual patient utility error beyond the MCID varied from one-third to two-thirds depending on timepoint assessed, but the mean for a cohort did not differ and could be employed for this purpose. Cite this article: Bone Jt Open 2022;3(7):573-581.

Keywords: Arthroplasty; BMI; EQ-5D; EQ-5D-3L; Outcome; Oxford Knee Score; Pearson correlation; Predictors; Spearman correlations; linear regression analysis; patient-reported outcome measure (PROM); t-test; total knee arthroplasty (TKA).