A Novel Scoring System for Diagnosing Systemic Lupus Erythematosus–Related Cytopenias

OBJECTIVE: To develop a score for a diagnosis of cytopenias from systemic lupus erythematosus (SLE) activity and determine the usefulness of bone marrow aspirate and biopsy (BMA/BMB) in this population. METHODS: We conducted a cohort study focusing on patients with SLE who underwent BMA/BMB as part of the evaluation for cytopenias. Etiology of cytopenias was categorized into SLE activity, drug-associated toxicity, and other diagnoses. We devised a scoring system, incorporating 5 factors, which were chosen and weighed based on their relative odds ratios on the analyzed models. RESULTS: A total of 115 patients were enrolled; 84.4% were women, and median age was 31 years (interquartile range [IQR], 23-42). Diagnoses for cytopenias were as follows: SLE activity in 47 patients (40.9%), drug-associated toxicity in 35 patients (30.4%), and other diagnoses in 33 patients (28.7%). Patients with SLE activity exhibited higher Systemic Lupus Erythematosus Disease Activity Index 2000 (SLEDAI-2K) scores ( p = 0.009) and anti-dsDNA levels ( p = 0.017). To enhance the diagnostic approach for patients with cytopenias secondary to disease activity, we introduced a scoring system with 5 variables: performing BMA/BMB due to suspected activity, absence of severe neutropenia, absence of azathioprine treatment, articular activity, and SLEDAI-2K score >6. The area under the curve was determined to be 0.85, indicating a sensitivity of 87.2% and a specificity of 70.5% when the cutoff value was set to ≥4.5 points. CONCLUSION: Disease activity and drug-associated toxicity are the main causes of cytopenias in SLE patients. We developed a scoring system with acceptable diagnostic performance to detect disease activity as the cause of cytopenias in patients with SLE.