Prevalence and clinical relevance of autoimmune neutropenia in patients with primary Sjögren's syndrome.

OBJECTIVE: To 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.

METHODS: The 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 x 10(9)/L) were first hospital admission caused by infection, development of systemic manifestations, neoplasia, and death.

RESULTS: Ninety-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 x 10(9)/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.

CONCLUSION: Neutropenia 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).