FRI0547 In hand osteoarthritis, decrease in synovitis results in less joint pain; a longitudinal magnetic resonanceimaging study

<h3>Background</h3> Current treatment options to alleviate pain in hand osteoarthritis (OA) are limited in number, efficacy, and safety. Local inflammation and subchondral bone activity are interesting as potential treatment targets, since synovitis and bone marrow lesions (BMLs) have the ability to change over time and were shown to have positive cross-sectional associations with joint tenderness. <h3>Objectives</h3> To investigate the longitudinal associations between features on magnetic resonance (MR) imaging and joint tenderness in patients with primary hand OA over two years. <h3>Methods</h3> Eighty-five consecutively included patients (81.2% women, mean age 59.2 years) with primary hand OA (89.4% fulfilling ACR classification criteria) from a rheumatology outpatient clinic received contrast-enhanced MR imaging (1.5T) and physical examination of the right hand interphalangeal joints of digits 2–5 at baseline and at follow-up two years later. MR images were scored paired in unknown time order, following the Hand OA MRI scoring system: synovitis, BMLs, and osteophytes on a 0–3 scale (higher score reflects worse condition), with half-point increments allowed for synovitis and BMLs delta-scores. Joint tenderness upon palpation was assessed by trained research nurses on a 0–3 ordinal scale. We tested the associations between decreased MR features and decreased tenderness by calculating odds ratios on joint level (n=680), using generalised estimating equations to account for the within patient effects. Additional adjustments were made for change in MR-defined osteophytes, synovitis, and BMLs, when appropriate. Similarly, we tested the associations between increased MR features and increased tenderness, and we explored interactions between the different MR features by stratifying for one another. <h3>Results</h3> Decrease in synovitis was seen in 90 joints and decrease in BMLs in 56, however when restricted to the 116 joints with baseline tenderness, at follow-up: 76 had reduced tenderness, 21 decreased synovitis, and 13 decreased BMLs. A decrease in synovitis, but not in BMLs, was associated with attenuated tenderness (table 1). Of 678 joints without maximum baseline tenderness, at follow-up: 115 had increased tenderness, 132 increased synovitis, 96 increased BMLs, and 44 increased osteophytes. An increase in synovitis, osteophytes, and, to a lesser extent, BMLs, was associated with increased tenderness (table 2). Through stratification it became apparent that BMLs were merely an effect modifier of the synovitis-tenderness association. <h3>Conclusions</h3> In hand OA, a decrease in MR-defined synovitis is associated with a decrease in joint tenderness. Furthermore, an increase in synovitis or osteophytes is associated with increased tenderness, which is further augmented by co-occurrence of BMLs. These findings support targeting synovitis in hand OA. <h3>Disclosure of Interest</h3> None declared