Comparison of five diagnostic flow cytometry scores in patients with myelodysplastic syndromes: Diagnostic power and prognostic impact

Flow cytometry (FCM) is a co‐criterion in myelodysplastic syndromes (MDS) diagnostics according to the WHO classification. The presented study compared diagnostic power and prognostic impact of different FCM‐based scores. A total of 807 bone marrow (BM) samples of patients with cytopenia (543 MDS, 153 non‐clonal cytopenias, 111 non‐MDS myeloid malignancies) and 78 healthy controls have been investigated using a standardized 8‐color‐FCM procedure. FCSS, Ogata‐score, iFS, RED‐score, and ELN‐NEC were analyzed for sensitivity and specificity in comparison to standard diagnostic tools. Median follow up for patients was 26 month (range: 0.2–89). The iFS showed the highest accuracy (80%) with the best balance between sensitivity (79%) and specificity (86%). This was also valid in MDS with very low IPSS‐R and even in MDS without ring sideroblasts, with normal blast count and karyotype, where iFS could confirm diagnosis in 62% and 65% of patients. Besides the high diagnostic power, the established iFS category “consistent with MDS” was associated with inferior overall survival (OS) independent from WHO classification (median: 51 month vs. not reached, p< 0.0001). Remarkably, this iFS category redefined a subgroup of patients with worse OS within IPSS‐R low‐risk category (73 month vs. not reached, p= 0.0433). Finally, multivariable analysis showed that iFS added independent prognostic information regarding OS besides IPSS‐R. The iFS separates non‐clonal cytopenias and MDS with the highest accuracy, provided information in addition to standard diagnostic procedures, and refined established prognostic tools for outcome prediction.