Objective To identify predictive factors for total knee replacement (TKR) using data from MRI of knee osteoarthritis patients in a phase III multicentre disease-modifying osteoarthritis drug (DMOAD) study.
Methods Knee osteoarthritis patients from a 2-year clinical trial evaluating licofelone versus naproxen were investigated for the incidence of TKR of the study knee. Patients (n=161) who completed the study according to protocol were selected. Incidence of TKR was assessed blindly to the treatment following telephone interviews (n=123).
Results 18 TKR (14.6%) were performed in 4–7 years following enrolment in the original study. More TKR were performed within the naproxen than the licofelone group (61% vs 39%, p=0.232). Baseline score of bone marrow lesions (BML) in the medial compartment (p=0.0001), medial joint space width (JSW) as assessed by standardised radiographs (p=0.0008), presence of severe medial meniscal tear (p=0.004), medial meniscal extrusion (p=0.013), and C-reactive protein level (p=0.049) were strong predictors of TKR. Changes at the end of the study also yielded strong predictors: change in cartilage volume of the medial compartment (p=0.005) and of the global knee (p=0.034), reduction in the JSW of greater than 7% (p=0.009), and WOMAC pain (p=0.009) and function (p=0.023) scores. Multivariate analysis showed that baseline severe medial meniscal tear (p=0.023) and presence of medial BML (p=0.025) were the strongest independent long-term predictors of TKR.
Conclusion This study shows that in the context of osteoarthritis trials, clinical data and structural changes identified by MRI allow prediction of a 'hard' outcome such as TKR. The findings support the usefulness and predictive value of MRI in defining study outcome in DMOAD trials.
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Funding This study was supported in part by grants from Merckle GmbH (Ulm, Germany) and ArthroLab Inc. (Montreal, Quebec, Canada).
Competing interests JPR is a consultant for ArthroVision Inc., MD is a consultant for ArthroLab Inc., JMP and JPP are consultants for and shareholders in ArthroLab Inc. and ArthroVision Inc. BH and DC received honoraria from ArthroLab Inc. FA is an employee of ArthroVision Inc.
Patient consent Obtained.
Ethics approval The post-hoc phone interviews were approved by the local ethics committees.
Provenance and peer review Not commissioned; externally peer reviewed.