POS0105 CHANGES IN RADIOGRAPHIC SIGNS IN PATIENTS WITH HAND OSTEOARTHRITIS DURING 2 YEARS

<h3>Background</h3> Hand osteoarthritis is a disorder that often evolves slowly. Some patients may have structural progression over a short term. <h3>Objectives</h3> We aimed to investigate which patients show radiographic progression over 2 years and what their determinants are. <h3>Methods</h3> Data from the ongoing HOSTAS (Hand OSTeoArthritis in Secondary care) cohort were used, consisting of 538 consecutive patients with primary hand OA diagnosed by their rheumatologist, followed for two years. Hand radiographs were obtained at baseline and year two. Questionnaires regarding demographics, disease and patient characteristics and the Australian Canadian Hand osteoarthritis index (AUSCAN) were collected. Hand radiographs were scored blinded, paired and in chronological order, using the Osteoarthritis Research Society International (OARSI) system (osteophytes (OP) and joint space narrowing (JSN), scored 0-3) per joint (summed for total 0-96). Intraobserver reliability was high, (intra-class correlation (ICC) 0.99 and 1.00 at baseline for OP and JSN sumscores, respectively). Reliability for change scores was high (ICC 0.77 and 0.86, for OP and JSN, respectively). The smallest detectable changes were 0.92 for OP (cut-off 1) and 1.32 for JSN (cut-off 2). Cut-offs were used to classify progressors (increase) or non-progressors (stable or decrease). Additionally, baseline radiographs were scored using the Kellgren-Lawrence system (0-4 per joint, total 0-120). Erosive disease was defined as at least 1 joint in the Verbruggen-Veys erosive or remodeling phase. Progressor and non-progressor groups were analysed for determinants using logistic regression. <h3>Results</h3> 442 patients had radiographs assessed at baseline and year 2, with mean (SD) age 61 (8.4) years and 85% female. Median (IQR) baseline OP/JSN sumscores were 9 (5-18) and 9 (4-19), respectively. Based on the SDC, 272/417 (65%) participants progressed on OP scores (median [IQR] change 1 [0-2]) and 135/419 (32%) on JSN scores (median [IQR] change 1 [0-2]). Four and 18 had a decrease in OP and JSN, respectively. Progression of OP was positively associated with erosive disease, measures of radiographic damage at baseline and female sex. Progression of JSN was positively associated with age, erosive disease and radiographic damage at baseline. Progression of JSN showed a positive association with changes in AUSCAN scores over 2 years. <h3>Conclusion</h3> Over 2 years, considerable radiographic progression was seen. Especially patients with erosive disease and the most severe radiographic damage at baseline were at risk for progression. Progression of JSN was associated with changes in pain and function. Progression in JSN was associated with age, whereas OP was with female sex. These findings may potentially represent different underlying pathogenetic mechanisms. <h3>REFERENCES:</h3> NIL. <h3>Acknowledgements:</h3> NIL. <h3>Disclosure of Interests</h3> Coen van der Meulen Grant/research support from: The HOSTAS study is supported by a grant from the Dutch Arthritis Society, paid to the institution, Lotte van de Stadt: None declared, Frits Rosendaal: None declared, Sjoerd van Beest: None declared, Margreet Kloppenburg Grant/research support from: The HOSTAS study is supported by a grant from the Dutch Arthritis Society, paid to the institution.