Presentation on theme: "Do Patients Assess Themselves Differently to Clinicians? Validation of the Lysholm Knee Scale Heather Smith Clinical Trials Manager RJAH Orthopaedic Hospital,"— Presentation transcript:
Do Patients Assess Themselves Differently to Clinicians? Validation of the Lysholm Knee Scale Heather Smith Clinical Trials Manager RJAH Orthopaedic Hospital, Oswestry, UK. Alan Tennant Professor of Rehabilitation Studies, University of Leeds, UK.
Overview Knee problems Outcome measures for knee surgery –Lysholm Knee Scale Lysholm scores rated by patients and physiotherapists as part of a RCT Rasch analysis of this data Level of agreement between raters Conclusions
Problems in the knee are common Trauma – e.g. a blow or twist to the knee while playing sports Degenerative – e.g. thinning of the cartilage leading to bone rubbing on bone Symptoms – pain, giving way, locking, limited range of motion Impact –activities of daily living, quality of life & socioeconomic impact
Various surgical procedures are performed on the knee to treat: Instability –anterior cruciate ligament reconstruction Malalignment –osteotomy Meniscal cartilage - debridement, meniscal transplant Bone - bone grafting Articular cartilage - microfracture, cell grafting
Numerous knee scales exist: WOMAC Meyers Score Tegner-Lysholm Activity Score Lysholm Knee Scale IKDC (subjective knee evaluation form) Cincinnati (modified) Knee Rating System Bentley Functional Rating Score KOOS Brittberg Hospital for Special Surgery Knee Scale Knee Society Knee Scale ADL Scale of the Knee Outcomes Survey
The Lysholm Knee Scale Lysholm & Gillquist (1982) –Measures pain, instability, locking, swelling, limp, stair-climbing, squatting and use of weight-bearing support –Designed for ligament injuries but used widely for chondral disorders –Not clear how the questions were chosen & weighted –Two items (Pain & Instability) make up 50% of the scores –Number of item response categories range from 3-6
Data from multi-centre trial -UK & Norway RJAH Orthopaedic Hospital, Oswestry
Physiotherapists independently assess patients
Procedure / Rasch analysis Data collected at pre-op from 157 patients Lysholm scores from physios and patients were pooled to fit the Rasch model Partial credit model in RUMM2020 was used DIF by gender & rater was tested Agreement between raters tested both statistically and graphically
Results Initially data misfit the model, p=< Pain, instability, locking & squatting were recoded to achieve ordered thresholds After removing the Swelling item (fit res. 4.22) overall fit to the model was good - mean item fit (SD 1.01).
Best fit & location of items ItemLocationFit res. Fit (p) Pain* Squatting* Instability* Limping Stairs Locking* Support *Some categories were collapsed Common Rare
Results cont. No uniform DIFF by gender or rater Stair-climbing showed slight non-uniform DIF by gender (p= 0.005) PCA of residuals confirmed strict unidimensionality (t-tests 7.8% (CI 5-10%)).
Conclusions The Lysholm Knee Scale in a revised form with 7 items meets rigorous measurement standards Original weighting is incorrect for type of patients Patient scores generally provide results that are interchangeable with clinicians’ scores Further analysis using post-op Lysholm data is planned to test targetting Data collected concurrently using sports knee questionnaires will also be analysed with possibility of constructing an item-bank