A 2-year, European Multicentre Study to Describe, Validate, and Predict Phenotypes of Knee Osteoarthritis

Rationale: Despite a large and growing disease burden in osteoarthritis (OA), many pharmaceutical companies have abandoned OA drug development. This is mainly due to the lack of appropriate outcome measures that can robustly identify patients that can benefit from a specific therapy. Different phenotypes of OA may benefit from different types of treatment. Therefore, novel markers to identify selected phenotypes of osteoarthritis may encourage drug development. Objective: To prospectively describe in detail pre-identified progressing phenotypes of patients with knee OA by use of conventional and novel clinical, imaging, and biochemical (bio)markers, and to validate and refine a predictive model for these (and new) progressing phenotypes based on these markers. Study design: APPROACH is an exploratory, European, five-centre, 2-year prospective follow-up, cohort study, with extensive measurements. In this study patients are treated according to regular care by their own physician with no study related treatment prescribed. Study related diagnostic and/or monitoring procedures are applied to the patients. Study population: Patients with tibiofemoral knee osteoarthritis, according to the clinical ACR classification criteria, pre-identified based on demographic (e.g. age), clinical (e.g. Pain NRS) and tissue structure (e.g. radiographic joint space width) parameters. Main study parameters/endpoints: Joint tissue structure based on radiographs, MRI, and biochemical (bio)markers as well as symptoms (pain, function) and quality of life by questionnaires. Secondary parameters: A multitude of (novel and conventional) clinical, imaging, and biochemical parameters related to osteoarthritis. Nature and extent of the burden and risks associated with participation, benefit and group relatedness: The participants will not have any direct benefit from their participation in this study other than that their OA is maximally diagnosed and followed in detail for up to 2 years (scr