Abstract:

Objective To explore the value of musculoskeletal ultrasound in the early differential diagnosis of seronegative rheumatoid arthritis (SNRA). Methods A total of 112 patients with swelling and positive tenderness of wrist or finger metacarpophalangeal joint, and proximal interphalangeal joint who for the first time visited the Department of the Rheumatology, the Second Hospital, Lanzhou University from January 2018 to December 2022 were selected. After 6 months of follow-up, patients were divided into the SNRA group(n=45) and the non-RA group(n=67). Musculoskeletal ultrasound was used to observe the two-dimensional gray scale (GS), power Doppler (PD) and bone erosion (BE) of synovial hyperplasia in the bilateral wrists, bilateral finger joints and tendons of the two groups, and semi-quantitative scoring was performed. Clinical data, such as age, gender, course of disease, C-reactive protein (CRP), and erythrocyte sedimentation rate (ESR) were recorded. The differences in ultrasound scores between the two groups were analyzed, and the correlations of ultrasound scores with course of disease, ESR, CPR in the SNRA group were also analyzed. The receiver operating characteristic (ROC) curve was used to evaluate the diagnostic efficacy of ultrasound indicators for SNRA. Results There were no significant differences in age, gender, and course of disease between the two groups (P>0.05). However, CRP and ESR levels were significantly higher in the SNRA group compared to the non-RA group (P<0.01). Joint GS, PD, and BE scores showed significant differences between the two groups (P<0.05), whereas tendon GS scores did not (P>0.05). Patients in the SNRA group had significantly higher tendon PD scores than the non-RA group (P<0.05). No significant differences were observed in lesion locations between groups (P>0.05), but patients in the SNRA group exhibited a significantly higher proportion of joint lesions and BE involvement compared to the non-RA group (P<0.05). Joint GS, PD, and BE grades also demonstrated significant differences between groups (P<0.01). Joint GS and PD scores in the SNRA group showed low positive correlations with CRP and ESR (r=0.366, 0.306, 0.444, and 0.384, respectively; all P<0.05). Tendon GS and PD scores exhibited moderate positive correlations with CRP and ESR (r=0.732, 0.532, 0.772, and 0.538, respectively; all P<0.05). Joint BE scores showed a moderate positive correlation with CRP (r=0.539; P<0.05). The sum of joint and tendon PD scores in the SNRA group demonstrated the highest diagnostic efficacy. Using a cutoff value of 10, the sensitivity and specificity for diagnosing SNRA were 82.2% and 90.0%, respectively. Conclusion Musculoskeletal ultrasound can be used as a non-invasive imaging method for the early differential diagnosis of SNRA.

Key words: seronegative rheumatoid arthritis, osteoarthritis, musculoskeletal ultrasound