Prevalence and Clinical Relevance of Autoimmune Neutropenia in Patients with Primary Sjögren's Syndrome

ObjectiveTo analyze the prevalence of neutropenia in a large cohort of patients with primary Sjögren's syndrome (SS) and its association with clinical and immunological disease expression and adverse outcomes.MethodsThe study cohort included 300 patients diagnosed with primary SS in our department between 1984 and 2002. The outcomes measured after the first laboratory evidence of neutropenia (<2.5 × 109/L) were first hospital admission caused by infection, development of systemic manifestations, neoplasia, and death.ResultsNinety-nine (33%) patients had neutropenia during the follow-up, which was related to neoplasia or drugs in 9 (3%) patients and was considered idiopathic in the remaining 90 (30%). Patients with neutropenia had a lower mean age at diagnosis of SS (51.9 versus 59.4 years, P < 0.001) and a higher prevalence of anti-Ro/La antibodies (53% versus 22%, P < 0.001), rheumatoid factor (49% versus 32%, P = 0.009), and low C4 levels (17% versus 8%, P = 0.044) than those without neutropenia. Patients with neutropenia had a higher incidence of hospital admission caused by infection (24% versus 9%, P = 0.002), especially those with neutropenia <1 × 109/L (50% versus 9%, P = 0.002), and a higher rate of admission (log rank = 0.0023) in comparison with those without neutropenia. Agranulocytosis was found in 7 (2%) patients, predominantly related to neoplasia (5 cases). One (1%) of the 90 patients with SS-related neutropenia developed large granular lymphocyte T-cell leukemia.ConclusionNeutropenia should be considered a relevant hematologic finding of primary SS, due both to its elevated prevalence and to its clinical significance (close association with anti-Ro/La antibodies, coexistence with other cytopenias, and development of severe infections).