Ultrasound shows swollen joints are the better proxy for synovitis than tender joints in DMARD-naïve early psoriatic arthritis
Sayam Dubash, Oras Alabas, Xabier Michelena, Leticia Garcia‐Montoya, Gabriele De Marco, Mira Merashli, Richard J. Wakefield, Paul Emery, Dennis McGonagle, Ai Lyn Tan, Helena Marzo‐Ortega
Abstract
Abstract Objective To evaluate the relationship between clinical examination/US synovitis in DMARD-naïve early PsA. Methods Eligible patients underwent matched clinical/US 44-joint assessment for tender and/or swollen joints (TJ/SJ) and US synovitis [grey scale (GS) ≥ 2 or power Doppler (PD) ≥ 1]. Statistical agreement between TJ/SJ, GS ≥ 2 and PD ≥ 1 was calculated by prevalence-adjusted and bias-adjusted κ (PABAK). To derive probabilities of GS ≥ 2/PD ≥ 1, mixed-effects logistic regression-modelled odds of US synovitis in TJ/SJ were conducted. Results In 155 patients, 5616 joints underwent clinical/US examination. Of these joints, 1039 of 5616 (18.5%) were tender, 550 of 5616 (9.8%) were swollen, 1144 of 5616 (20.4%) had GS ≥ 2, and 292 of 5616 (5.2%) had PD ≥ 1. GS ≥ 2 was most prevalent in concomitantly tender and swollen joints [205 of 462 (44%)], followed by swollen non-tender joints [32 of 88 (36.4%)], tender non-swollen joints [148 of 577 (25.7%)] and non-tender non-swollen joints (subclinical synovitis) [759 of 4489 (16.9%)]. Agreement between SJ/PD ≥ 1 was high at the individual joint level (82.6–96.3%, PABAK 0.65–0.93) and for total joints combined (89.9%, PABAK 0.80). SJ/GS ≥ 2 agreement was greater than between TJ/GS ≥ 2 [73.5–92.6% vs 51.0–87.4% (PABAK 0.47–0.85 vs PABAK 0.35–0.75), respectively]. Swelling was independently associated with higher odds of GS ≥ 2 [odds ratio (OR) (95% CI); 4.37 (2.62, 7.29); P < 0.001] but not tenderness [OR = 1.33 (0.87, 2.06); P = 0.192]. Swelling [OR = 8.78 (3.92, 19.66); P < 0.001] or tenderness [OR = 3.38 (1.53, 7.50); P = 0.003] was independently associated with higher odds of PD ≥ 1. Conclusion Synovitis (GS ≥ 2 and/or PD ≥ 1) was more likely in swollen joints than in tender joints in DMARD-naïve, early PsA. Agreement indicated that swollen joints were the better proxy for synovitis, adding to greater understanding between clinical and US assessments.