Monoclonal gammopathy related to Sjögren syndrome: A key marker of disease prognosis and outcomes

Abstract Objective To analyze the monoclonal expression of SS through the detection of serum monoclonal immunoglobulins (mIgs) in a large series of patients with Sjögren syndrome (SS), focusing on the etiology, characterization and evolution of the monoclonal band and the association with SS clinical expression and outcomes. Methods Serum immunoelectrophoresis (IE) was performed to 408 consecutive patients who were evaluated by our unit between 1992 and 2011: 221 patients who fulfilled the 2002 American–European criteria for primary SS, 122 primary SS patients who fulfilled exclusively the 1993 European criteria and 65 patients with SS-associated hepatitis C virus infection. IE was performed at diagnosis and every year during the follow-up. Results Of the 221 patients with primary SS, 48 (22%) had monoclonal gammopathy. In the control groups, the prevalence was 16% in patients with SS who fulfilled the 1993 criteria ( p > 0.05) and 52% in SS-HCV patients ( p