Categorization of changes in the Oxford Knee Score after total knee replacement: an interpretive tool developed from a data set of 46,094 replacements

Objectives The objective of the study was to create an interpretive categorical classification for the transition in the Oxford Knee Score (OKS) change score (ΔOKS) using the anchor-based method. Study Design and Setting Registry data from 46,094 total knee replacements from the year 2014/15, were accessed via the Health and Social Care Information Center official website. Data included preoperative and 6-month follow-up OKS and response to the transition anchor question. Categories were determined using Gaussian approximation probability and k-fold cross-validation. Results Four categories were identified with the corresponding ΔOKS intervals: “1. much better” (≥16), “2. a little better” (7–15), “3. about the same” (1–6), and “4. much worse” (≤0) based on the anchor questions’ original five categories. The mean 10-fold cross-validation error was 0.35 OKS points (95% confidence interval 0.12 to 0.63). Sensitivity ranged from 0.34 to 0.68; specificity ranged from 0.74 to 0.95. Conclusion We have categorized the change score into a clinically meaningful classification. We argue it should be an addition to the continuous OKS outcome to contextualize the results in a way more applicable to the shared decision-making process and for interpreting research results

It is good to feel better, but better to feel good : Whether a patient finds treatment successful' or not depends on the questions researchers ask

Introduction: In sports physiotherapy, medicine and orthopaedic randomised controlled trials (RCT), the investigators (and readers) focus on the difference between groups in change scores from baseline to follow-up. Mean score changes are difficult to interpret (is an improvement of 20 units good?'), and follow-up scores may be more meaningful. We investigated how applying three different responder criteria to change and follow-up scores would affect the outcome' of RCTs. Responder criteria refers to participants' perceptions of how the intervention affected them. Methods: We applied three different criteria - minimal important change (MIC), patient acceptable symptom state (PASS) and treatment failure (TF) - to the aggregate Knee injury and Osteoarthritis Outcome Score (KOOS 4 ) and the five KOOS subscales, the primary and secondary outcomes of the KANON trial (ISRCTN84752559). This trial included young active adults with an acute ACL injury and compared two treatment strategies: exercise therapy plus early reconstructive surgery, and exercise therapy plus delayed reconstructive surgery, if needed. Results: MIC: At 2 years, more than 90% in the two treatment arms reported themselves to be minimally but importantly improved for the primary outcome KOOS 4 . PASS: About 50% of participants in both treatment arms reported their KOOS 4 follow-up scores to be satisfactory. TF: Almost 10% of participants in both treatment arms found their outcomes so unsatisfactory that they thought their treatment had failed. There were no statistically significant or meaningful differences between treatment arms using these criteria. Conclusion: We applied change criteria as well as cross-sectional follow-up criteria to interpret trial outcomes with more clinical focus. We suggest researchers apply MIC, PASS and TF thresholds to enhance interpretation of KOOS and other patient-reported scores. The findings from this study can improve shared decision-making processes for people with an acute ACL injury

What is the effect of supervised rehabilitation regime vs. self-management instruction following unicompartmental knee arthroplasty? – a pilot study in two cohorts

PURPOSE: The optimal rehabilitation strategy after a unicompartmental knee arthroplasty (UKA) is unclear. This study aims to compare the effect of transitioning from a supervised to a self-management rehabilitation regime by pilot study of patient outcomes subsequent to UKA surgery. METHODS: Fifty consecutive patients scheduled to undergo unilateral UKA surgery at our institution between 22(nd) February 2016 and 18(th)of January 2017 were prospectively identified via local medical database and included. Performed UKAs were grouped into two cohorts, Supervised Cohort and Self-management Cohort, temporally separated by introduction of new rehabilitation. Self-management Cohort(n = 25) received an extensive inpatient rehabilitation regime along with outpatient referral to rehabilitation center. The Self-management Cohort(n = 25) were only instructed in use of crutches and free ambulation at own accord. Follow-up (F/U) was 1 year from receiving UKA. A range of outcomes were recorded, and between-cohort differences compared: knee joint range of motion, pain and functional limitations, length of stay (LOS), readmission rate, pain during activity and rest, and knee circumference. RESULTS: Complete data was obtained for n = 45 patients. The mean between-cohort difference in ROM (range of motion) from preoperatively to discharge was 15.4 degrees (CI:5.2,25.8, p = 0.004), favoring the supervised regime, with no difference detected in any outcome at 3- or 12 months F/U. Median LOS was 1 day in both cohorts. CONCLUSION: Transition to a simple rehabilitation regime following UKA surgery was associated with decreased ROM at discharge, which was not present at 3-month F/U. We found no other between-cohort differences for any other outcomes at 3- and 12-month F/U including functional limitations, although the study was likely underpowered for these outcomes. We encourage large-scale replication of these findings using randomized designs. LEVEL OF EVIDENCE: Therapeutic level I

Unlike ROC analysis, a new IRT method identified clinical thresholds unbiased by disease prevalence

Objective: This study introduces a new method to establish clinical thresholds for multi-item tests, based on item response theory (IRT), as an alternative to receiver operating characteristic (ROC) analysis. The performance of IRT method was examined and compared with the ROC method across multiple simulated data sets and in a real data set. Study Design and Setting: Simulated data sets (sample size: 1,000) varied in means and variability of the test scores and the prevalence of disease. The true clinical threshold was defined as a predetermined location on the latent trait underlying the questionnaire, with its corresponding expected test score. The real data set (sample size: 295) comprised Hospital Anxiety Depression Scale (HADS) depression scores and Diagnostic and Statistical Manual of Mental Disorders-Fourth Edition major depressive disorder (MDD) diagnoses. Results: The IRT method recovered the clinical thresholds without bias, whereas the ROC method identified thresholds that were biased by the prevalence of disease. Mild MDD was clinically diagnosed in 23%, moderate MDD in 12%, and severe MDD in 14% of the participants. The IRT method identified the following HADS depression score thresholds for mild, moderate, and severe MDD: 10.7, 13.2, and 15.1, respectively. Conclusion: The new IRT method identifies clinical thresholds that are unbiased by disease prevalence