Role of serum immunoglobulins for predicting sarcoidosis outcome: A cohort study

Background: Sarcoidosis is a systemic granulomatous disease which carries variable outcomes. Serum protein electrophoresis is an easily accessible and routinely performed examination at diagnosis, in order to search for hypergammaglobulinemia, which is frequently found, and to rule out other granulomatous diseases such as common variable immunodeficiency. We aimed to assess the impact of baseline immunoglobulin level on the outcome of sarcoidosis. Methods: We conducted a retrospective cohort-study, at Rennes University Hospital, in which all newly diagnosed patients for whom a serum protein electrophoresis had been performed at baseline were enrolled, from 2006 to 2014. The main outcome was the need for corticosteroid treatment within 2 years from diagnosis, the secondary outcome was the occurrence of relapse among treated patients. Results: Eighty patients were included in the study, and 41.25% of them exhibited an elevated globulins rate. In univariate analysis, an elevated ACE level >70 U/l, Afro-Caribbean origin, and extra-pulmonary involvement, were associated with the need for corticosteroid treatment. In multivariate analysis, only ACE elevation (OR = 1.03, IC95% 1.01–1.05, p = 0.009) and extra-pulmonary involvement (OR = 5.8, IC95% 1.4–24, p = 0.015) were significant. Immunoglobulin level was not associated with the main outcome. Regarding the secondary outcome, none of the studied features were predictive of relapse among the 34 treated patients followed for two years. Conclusions: There was no relation between the immunoglobulin level at diagnosis and the evolution of sarcoidosis. An elevated ACE level and the presence of initial extra-pulmonary involvement were both associated with a more severe course of the disease necessitating a corticosteroid treatment.