Impact of autoimmune cytopenias on severity of childhood-onset systemic lupus erythematosus: A single-center retrospective cohort study

Objective To assess whether children with autoimmune cytopenias prior to or at diagnosis of systemic lupus erythematosus (cSLE), differ phenotypically from other cSLE patients; and have a lower risk and severity of lupus nephritis (LN) as observed in prior adult studies. To assess the effect of prior immune therapy for autoimmune cytopenias on 2-year risk of LN. Methods This was a retrospective cohort study of incident cSLE cases. We included patients aged less than 17 years at diagnosis. We excluded patients with LN at cSLE diagnosis. Our follow-up period was 2 years. We defined autoimmune cytopenias as either autoimmune hemolytic anemia, immune thrombocytopenia or Evan’s syndrome. Results Forty-three (33%) of the 130 patients had autoimmune cytopenias before or at cSLE diagnosis. Those with autoimmune cytopenias had significantly more neuropsychiatric symptoms and higher mean ESR but less arthritis, malar rash and myositis versus those without autoimmune cytopenias. They had lower 2-year incidence proportion of LN compared to other cSLE patients (7% vs 15%). Of the 16 patients who developed LN, those with autoimmune cytopenias had mostly class V (2 of 3 patients) versus mostly class III and IV in those without autoimmune cytopenias (6 of 12 patients). None of the 13 patients pre-treated for autoimmune cytopenias developed LN. Conclusion Patients with autoimmune cytopenias before or at cSLE diagnosis have intriguing differences from other cSLE patients. They may represent a unique sub-type of cSLE patients and should be further explored.