The Oxford knee score and its subscales do not exhibit a ceiling or a floor effect in knee arthroplasty patients: an analysis of the National Health Service PROMs data set
- 408 Downloads
In this study, we examined whether the OKS demonstrated a floor or a ceiling effect when used to measure the outcome of knee replacement surgery in a large national cohort.
NHS PROMs database, containing pre- to 6 month post-operative OKS on 72,154 patients, mean age 69 (SD 9.4), undergoing knee replacement surgery, was examined to establish the proportion of patients achieving top or bottom OKS values pre- and post-operatively.
Pre-operatively, none of patients achieved the maximum/‘best’ (48) and minimum (0) scores. Post-operatively, no patients (0 %) achieved the minimum/‘worst’ score, but the percentage achieving the maximum score increased to 2.7 %. Subgroup analyses demonstrated that the highest post-operative overall ceiling percentage was 3 %, in a subgroup of patients between 60 and 79 years of age and 13.7 % in a group of patients who had a pre-operative OKS above 41. Furthermore, 10.8 % of patients achieved the top post-operative OKS-PCS and 4.7 % top post-operative OKS-FCS.
Based on NHS PROMs data, the OKS does not exhibit a ceiling or floor effect overall, or for both its pain and function subscales, and remains a valid measure of outcomes for patients undergoing TKA.
Level of evidence
Large-scale retrospective observations study, Level II.
KeywordsKnee Arthroplasty Oxford Score Ceiling Floor Pain Function Subscale OKS Patient Reported Outcome
- 7.UK Government, Department of Health (2009) Guidance on the routine collection of patient reported outcome measures. http://webarchive.nationalarchives.gov.uk/+/www.dh.gov.uk/en/Publicationsandstatistics/Publications/PublicationsPolicyAndGuidance/DH_092647
- 26.Xie F, Li S, Lo N, Yeo S, Yang K, Yeo W, Chong H, Fong K, Thumboo J (2007) Cross-cultural adaptation and validation of Singapore English and Chinese versions of the Oxford knee score (OKS) in knee osteoarthritis patients undergoing total knee replacement. Osteoarthritis Cartilage 15(9):1019–1024CrossRefPubMedGoogle Scholar