Background/Purpose: Recent clinical practice has increasingly utilized musculoskeletal (MS) ultrasound studies to assess inflammation and soft-tissue abnormalities of the joints, such as synovitis and bone erosions. MS ultrasound studies were recently shown to be more sensitive to detect early synovial changes and erosions while maintaining cost-effectiveness compared to other radiographic imaging. Rheumatoid factor (RF) and anti-cyclic citrullinated peptide antibodies (anti-CCP Ab) have demonstrated key roles in the diagnosis of RA, yet the positive expressivity of these antibodies has been reported as low as 50% in early RA disease. The nature of seronegative RA, which is often subclinical in presentation, has shown further elusiveness in detection, disease course, and treatment response. We hypothesize that MS ultrasound studies are sensitive to and critical in detecting inflammatory changes in seronegative inflammatory arthritis (SNIA) as compared to serological studies in conjunction with physical examination.

Methods: A retrospective analysis of electronic medical records was conducted on patients at two University at Buffalo rheumatology clinics who underwent MS ultrasound studies to rule out inflammatory arthritis. These patients did not meet diagnostic criteria for RA due to a lack of positive serology and/or gross joint swelling, and were previously evaluated by at least one other medical provider who found no evidence of inflammatory arthritis on physical examination or prior family history of psoriatic or other inflammatory arthritis. Data relating to patients’ demographics, MS ultrasound findings, and serological studies was de-identified and tabulated. Measurements of synovial hypertrophy and erosions were categorized by location and presence with immunosuppressive therapy. Further subgroup analysis was performed by analyzing patients with multiple ultrasounds to assess inflammatory disease progression.

Results: Of the 363 patients who underwent MS ultrasound studies, 280 of them (77.1%) of them were found to have synovial hypertrophy [minimal = 21%, mild = 47%, moderate = 30%, severe = 2%] in bilateral MCP, PIP, carpal, wrist, and/or MTP and IP joints, therefore conferring a diagnosis of inflammatory arthritis. The average age of these 280 patients was 48.35 ± 14.86 years old at the time of diagnosis, with female to male ratio of 4.38:1. Surprisingly, of these 280 patients with evidence of inflammatory arthritis, 69 (24.6%) of them were found to have joint erosions with either MCP or MTP joints, supporting a diagnosis of advanced inflammatory arthritis with erosive disease. The erosions were predominantly located in MTP joints (77.1%) as compared to MCP joints (22.9%). Disease progression in these patients was further analyzed using repeat MS ultrasound studies following immunosuppressive therapy.

Conclusion: Our findings clearly demonstrated distinct clinical and ultrasonography features of SNIA. MS ultrasound studies are sensitive to and critical for detecting inflammatory changes and joint damages in SNIA due to its subclinical presentation. Based on our findings, SNIA is likely underdiagnosed in individuals who complain of joint pain without gross synovitis on physical examination.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/detecting-inflammatory-changes-in-seronegative-inflammatory-arthritis-with-use-of-musculoskeletal-ultrasound-studies/