Ultrasound (US) subclinical synovitis in prerheumatoid arthritis (RA) patients has been demonstrated in anticitrullinated antibodies (ACPA) positive patients to be predictive for future development of RA. The aim of the study was to assess the value of the US as a predictive factor for the future development of RA in patients with polyarthralgia without ACPA.
Eighty consecutive ACPA-patients with polyarthralgia without clinical synovitis or ACPA before the US examination were included. To detect significant US synovitis, we applied the criteria of a US score (SONAR) validated among RA patients and controls. The diagnosis of RA was based on the ACR/EULAR criteria.
Significant US synovitis were present at baseline in 20 (25%) of the patients. The mean (SD) follow-up time was 18 (7) months in both groups. Seven (9%) patients developed a clear RA and 2 another inflammatory arthritis. US synovitis at baseline was significantly associated with evolution to RA: 5/20 (25%) versus 2/60 (3%) (P<0.05). The free time to RA was significantly shorter when US synovitis were present (P<0.01). Moreover, after multivariate analysis, US appeared to be the only independent predictor of an evolution to RA (OR: 7.4). Results remained similar after including all patients developing another inflammatory arthritis.
Our study suggests that US can be used as a predictor for the evolution to RA or other inflammatory arthritis in patients presenting polyarthralgia without ACPA.