Anti-CCP status determines the power Doppler oscillation pattern in rheumatoid arthritis: a prospective study

Abstract

Rheumatoid arthritis (RA) is a chronic inflammatory disease leading to joint destruction. Serologically, it can be differentiated according to rheumatoid factor (RF), anti-cyclic citrullinated peptide antibodies (anti-CCP), or both. This differentiation is prognostically and therapeutically relevant. No method has been described to separate the two forms phenotypically. We hypothesize that a differentiation is possible by evaluating oscillation patterns in power Doppler sonography (PDS). In a prospective study, 20 patients with anti-CCP-positive RA and 20 patients with anti-CCP-negative RA with active wrist synovitis were examined. A PDS scan was performed, and perfusion maxima (P _max) and minima (P _min) as well as the amplitude (ΔP) were determined by a blinded study member. The amplitude was standardized (sΔP) by dividing by P _max, and the anti-CCP-positive and anti-CCP-negative patients as well as the RF-positive and RF-negative were compared to each other. In the ultrasonographic evaluation, we found a highly significant difference in sΔP between CCPp and CCPn patients (median 19.0 vs. 42.9 %, p < 0.0001). sΔP is independent of disease activity. The absolute amplitude ΔP did not differ between the groups. Also, in anti-CCP-positive patients there was a completely linear correlation between P _max and P _min, and this was far less marked in anti-CCP-negative patients. Anti-CCP-positive and anti-CCP-negative RA display different PDS oscillation patterns. This constitutes a nonserological parameter to differentiate between the two forms. The difference in PDS oscillation patterns suggests that the underlying pathological process differs between the forms.

Keywords: Anti-CCP; Power Doppler sonography; Rheumatoid arthritis; Rheumatoid factor; Ultrasonography.