FRI0317 Separate quantitative features of early radiographic knee osteoarthritis: Development over five years and relation with symptoms in the check cohort
Authors: P.M. Welsing, M.B. Kinds, A.C. Marijnissen, J.W. Bijlsma, M. Boers, F.P. Lafeber
Journal: Annals of the Rheumatic Diseases (2013)

<h3>Background</h3> Knee Images Digital Analysis (KIDA) has been developed to measure separate parameters of radiographic osteoarthritis (OA) damage of the knee in more detail on a continuous scale (quantitative). <h3>Objectives</h3> To evaluate whether quantitative measurement of knee radiographs enables identification of different domains of joint damage in very early OA, important for the evaluation of onset and progression of OA. And to evaluate whether these radiographic features progress, are related with each other and with clinical characteristics during five-year follow-up in early OA. <h3>Methods</h3> Knee radiographs from the Cohort Hip &amp; Cohort Knee (CHECK; n=1002 participants) were evaluated with KIDA. CHECK is a prospective study (ten-year) on early OA in ten Dutch hospitals. Separate radiographs of both knees from baseline, two-year and five-year follow-up were evaluated. KIDA measurement provides per radiograph 14 parameters of joint damage. A principal component analysis aided decisions on how to best combine the KIDA parameters into domains that represent specific separate radiographic OA characteristics. These features were evaluated for development, and were related to each other and to clinical outcome using T0, T2y, and T5y radiographs. <h3>Results</h3> In this cohort with very early symptoms related to OA, minimum JSW, medial JSW, lateral JSW, varus angle, osteophyte area (sum of lateral and medial femur, and lateral and medial tibia), eminence height (sum of lateral and medial eminence), and bone density (mean of lateral and medial femur and tibia) were identified as radiographic features. The features progressed in radiographic severity at different times in follow-up: early (medial JSW, osteophyte area), late (minimum and lateral JSW, eminence height), and both early and late (varus angle, bone density). The separate radiographic features were statistically significantly (p&lt;0.05) correlated to each other, and correlations varied between different time points. The JSW features were most strongly related to each other (up to r=0.82), but also e.g. osteophytes and bone density were significantly correlated (largest r=0.33). The relations with clinical outcome varied over time, and relations were most commonly found for osteophyte area and JSW. E.g. the presence of pain at T0 was associated with minimum, medial, and lateral JSW, varus angle, osteophyte area, and eminence height at T0 (odds ratio; OR=0.81, 0.70, 1.38, 0.74, 1.43, and 1.08 respectively). At T2y pain presence was associated with lateral JSW, varus angle, and osteophyte area (OR=0.87, 1.17, 1.42), and at T5y associations were found with minimum JSW, osteophyte area, and bone density (OR=0.79, 1.47, and 1.04). Radiographic features were also associated with WOMAC pain and function score at different time points. <h3>Conclusions</h3> The separate radiographic features, which were identified by quantitative measurement with KIDA, all progressed over five years in this early OA cohort. Progression occurred at different rates between time points. The relations between the radiographic features and with clinical outcome varied over time. This implies that longitudinal evaluation of separate features will give further insight in OA progression. <h3>Disclosure of Interest</h3> None Declared