Tender Joints Are a Better Indicator of Synovitis Than Swollen Joints in DMARD-Naive Early PsA

Swollen joints are a better proxy for synovitis than tender joints in patients with early psoriatic arthritis (PsA), according to study results published in Rheumatology Advances in Practice.

Researchers sought to examine the association between findings from joint clinical examinations and ultrasound-detected synovitis in patients with early PsA.

Patients with PsA were enrolled in the current study from an arthritis clinic in Leeds, England, between December 2013 and October 2019. Eligible patients had no prior or current exposure to disease-modifying antirheumatic drugs (DMARDs). Participants underwent matched clinical/ultrasound 44-joint assessment for tender and/or swollen joints (TJ/SJ) and ultrasound synovitis. On ultrasound, grades of grey scale (GS) and power Doppler (PD) were scored for each scanned joint on a scale of 0 to 3. Synovitis was defined as GS of at least 2 or PD of at least 1.

Statistical agreement between TJ/SJ, GS, and PD was calculated by prevalence-adjusted and bias-adjusted kappa (PABAK). Mixed-effects logistic regression models were used to estimate the odds of ultrasound synovitis in TJ/SJ.

The study cohort included 155 patients, with a mean age of 44.4±12.8 years, among whom 52.9% were women. A total of 5616 joints were examined by clinical and ultrasound examination.

Overall, 1039 (18.5%) joints were tender, 550 (9.7%) were swollen, 1144 (20.4%) had GS of at least 2, and 292 (5.2%) had PD of at least 1. The GS of at least 2 was most prevalent in joints that were both tender and swollen (44%), followed by swollen nontender swollen joints (36.4%), tender nonswollen joints (25.7%), and nonswollen nontender joints (16.9%).

Researchers noted that the agreement at the individual joint level was highest between SJ and PD of at least 1 (82.6%-96.3%; PABAK, 0.65-0.93). The SJ/GS agreement was greater than the TJ/GS agreement 2 (73.5%-92.6% vs 51.0%-87.4%).

In regression models, swelling was independently associated with higher odds of GS of at least 2 (odds ratio [OR], 4.37; 95% CI, 2.62-7.29; P <.001), but tenderness was not. However, both swelling (OR, 8.78; 95% CI, 3.92-19.66; P <.001) and tenderness (OR, 3.38; 95% CI, 1.53-7.50; P =.003) were independently associated with higher odds of PD of at least 1.

Results from the study suggested that synovitis was more likely in swollen joints than tender joints in patients with DMARD-naive early PsA.

One of the study limitations was the concomitant use of nonsteroidal anti-inflammatory drugs (NSAIDs) among some patients, which may have affected inflammation levels on ultrasound.

“These findings add to the understanding of how clinical examination relates to underlying pathologies on [ultrasound] imaging, which might help to improve the management of early PsA,” the researchers wrote.

Disclosure: Several study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of authors’ disclosures. 

Reference

Dubash SR, Alabas OA, Michelena X, et al. Ultrasound shows swollen joints are the better proxy for synovitis than tender joints in DMARD-naïve early psoriatic arthritis. Rheumatol Adv Pract. 2021;5(3):rkab086. doi:10.1093/rap/rkab086