Lupus thrombocytopenia: clinical implications and prognostic significance
Objectives: To clarify clinical manifestations, association with disease activity, and prognostic impact of thrombocytopenia using simple and reliable indices. Methods: 632 patients were reviewed retrospectively. Fifty patients with thrombocytopenia were included as cases and matched with 100 control patients. Clinical manifestations at first thrombocytopenic episode were recorded. Classification criteria at diagnosis, basic immunological profiles, disease activity (ECLAM), and end organ damage (SLICC) were recorded. Results: 29/50 (58%) had thrombocytopenia at diagnosis of lupus. Haemorrhagic manifestations were associated with the degree of thrombocytopenia (p<0.001). Anticardiolipin antibodies were not related to the degree of thrombocytopenia or the severity of haemorrhagic manifestations. Megakaryocytes were normal or increased in 26/28 (93%) bone marrow specimens, indicating peripheral platelet destruction. Patients with high disease activity were more thrombocytopenic than controls (OR=2.61, 95% CI 1.13 to 5.96, p=0.009). Patients with low C3 or CH50 were more likely to be thrombocytopenic (OR=2.36, 95% CI 1.05 to 5.26, p=0.029). Median SLICC for lupus patients with thrombocytopenia was 2 (range 0-11) compared with 1 (range 0-12) for controls (p<0.001). No deaths occurred during thrombocytopenic episodes. Conclusions: Thrombocytopenia is not directly associated with end organ damage and mortality, but defines a subgroup of patients with higher morbidity and is thus a major complication of systemic lupus erythematosus, affecting overall prognosis.