Ultrasound tenosynovitis: A differential feature of patients with seronegative rheumatoid arthritis.

OBJECTIVE: To identify differential features between patients with seropositive and seronegative rheumatoid arthritis (RA).

METHOD: Prospective cohort study, including patients who were admitted for polyarthralgia. At baseline was performed: laboratory studies, X-rays of hands and feet, ultrasound of both hands with power Doppler technique, clinical data and clinimetry. In subsequent visits the definitive diagnosis of RA was established or not. It was considered as seronegative RA when patients were negative for both RF and ACPAs.

RESULTS: 746 patients were included, of which 128 (17.1%) ended with a final diagnosis of RA. Of these 128 patients, 87 (67.9%) were seropositive RA, while 41 (32%) were seronegative RA. The only feature that showed significant differences was the presence of tenosynovitis detected by ultrasound with a positive power Doppler signal, 13.7% of the patients with seropositive RA vs 41.6% of the patients with seronegative RA (p=0.0028).

CONCLUSION: The only differential feature of patients with seronegative RA was the higher proportion of tenosynovitis detected by ultrasound.