ACPA-positive versus ACPA-negative rheumatoid arthritis: two distinct erosive disease entities on radiography and ultrasonography

The objective of this study is to assess the prevalence, localization, and severity of bone erosions on radiography (RX) and ultrasonography (US) according to ACPA status in patients with rheumatoid arthritis (RA). 78 patients with ACPA-positive (ACPA+) RA and 30 patients with ACPA-negative (ACPA−) RA fulfilling the ACR 1987 and/or ACR/EULAR 2010 criteria were consecutively included. On RX, a modified Sharp erosion score (SHSe) was evaluated by two blinded readers and one adjudicator for discordant cases (number of eroded joints ≤ three). On US, erosions were scored on six bilateral joints (MCP2, 3, 5; MTP2, 3, 5) with a four-point scale to calculate the total US score for erosions (USSe). The mean total SHSe and USSe were 3.7 and 4.4 times higher in the ACPA+ group than in the ACPA− group, respectively (P