Objective: To determine the clinical features associated with histologically proven rheumatoid vasculitis (HRV) and the additional diagnostic value of serological markers in an inception cohort of 81 patients with rheumatoid arthritis (RA) suspected of RV.

Methods: The presence and number of recently developed extra-articular manifestations (EAMs) and a weighted EAM score, as well as the levels of serological markers, were compared between 31 patients with RA with histologically proven vasculitis and 50 patients with RA in whom vasculitis could not be documented histologically. The following markers were evaluated: circulating immune complexes, complement components C3 and C4, class-specific rheumatoid factors (IgM RF, IgG RF, IgA RF), antineutrophil cytoplasmic antibodies, antinuclear antibodies, antiendothelial antibodies, circulating intercellular adhesion molecule-1 and -3, circulating vascular cell adhesion molecule and E-selectin, cellular fibronectin, von Willebrand factor antigen, and C reactive protein. The diagnostic value of these markers, in addition to the clinical features, was evaluated with logistic regression analysis.

Results: Peripheral neuropathy or purpura/petechiae, or both, were the most important clinical features to discriminate patients with RA with and without histologically proven RV. The presence of a high number of EAMs and a higher weighted EAM score in patients with RA suspected of vasculitis were also associated with an increased probability of histologically proven RV. After adjustment for EAMs, only the combination of an increased serum IgA RF level and a decreased serum C3 level appeared to make an additional contribution to the diagnosis histologically proven RV. Evidence of systemic vasculitis was found in a muscle biopsy of the rectus femoris in 9/14 (64%) patients with vasculitis with neuropathy and in 3/11 (27%) patients with purpura/petechiae and vasculitis of the skin.

Conclusions: In the diagnostic process of RV the presence of peripheral neuropathy and/or purpura/petechiae or a high weighted EAM score will increase the probability of histologically proven RV. Of the circulating factors previously suggested to be markers for RV only IgA RF and C3 further increase the probability of histologically proven RV and may be useful to guide diagnostic decisions.