AB0815 THE INFLUENCE OF NON-STEROIDAL ANTI-INFLAMMATORY DRUGS ON INFLAMMATORY SONOGRAPHIC FEATURES IN EROSIVE HAND OSTEOARTHRITIS

Abstract

Background Erosive hand osteoarthritis (HOA) is a subtype of hand osteoarthritis affecting the interphalangeal (IP) finger joints, characterized by a more inflammatory burden. Hitherto, pharmacologic treatment options are restricted to symptomatic therapy like paracetamol and/or non-steroidal anti-inflammatory drugs (NSAIDs)(1). The latter may affect the presence of inflammatory features on ultrasound (US). Hence, assessment of the disease activity could be influenced by this treatment. Objectives To examine whether inflammatory US features (i.e. synovial proliferation (SP), effusion (EFF) and Power Doppler (PD) signal) in erosive HOA patients change when discontinuing NSAIDs intake for two weeks before the US assessment. Methods Ninety-nine patients with erosive HOA, according to American College of Rheumatology criteria (2) were enrolled. Presence of central erosions on conventional radiographs and any clinical sign of inflammatory activity (soft tissue swelling) in at least one proximal or distal IP finger joint were present. The patients were allocated to the NSAIDs or control group according to their intake before baseline (if no NSAIDs use = control group; if intake of NSAIDs on a regular base = NSAIDs group). At baseline (T0), 16 IP finger joints were examined by US. Patients in the NSAIDs group were asked to discontinue all NSAIDs intake for two weeks, when another US was performed (T1). The inflammatory features were scored at T0 and T1 using a semi-quantitative scale ranging from 0-3 (3). Binomial mixed models with logit function were fitted for ultrasound scores SP (score>2), EFF (score>2), and PD (score>1) with a random intercept for patient and with age (in years), sex (female vs. male), duration of illness (in years), joint, side (left vs. right), anatomical phase group (N, S, J vs. E/R, R, E, F), NSAID group (NSAIDs withdrawal vs. No NSAIDs), time (t1 vs. t0), and a two-way interaction between NSAIDs group * time as fixed factors. The Odds ratios (OR, 95% confidence interval (CI)) of having an ultrasound score of at least ‘2’ versus at most ‘1’ for SP and EFF, and ‘0’ vs. ‘≥1’ for PD are shown. Results Forty seven patients were included in the NSAIDs group and 52 in the control group. Both groups were comparable at baseline for VAS pain, disease duration, number of radiographic affected joints and body mass index, but not for age (p=0.005). The US baseline data were comparable between both groups (all p>0.05). At T1, in the NSAIDs withdrawal group, more SP and PD was seen compared to baseline (p = 0.018 and 0.031, respectively). However, the interaction term time*NSAIDs was not found significant for any variable (table 1). Conclusion No significant changes in inflammatory US features were seen in erosive HOA patients after withdrawal of NSAIDs for two weeks. This study suggests that an NSAIDs free period is not necessary before assessing inflammatory disease activity in erosive HOA patients.