The diagnostic gold standard for myelodysplastic syndrome (MDS) is based on bone marrow morphology, progenitor cell count and cytogenetics. But the dysplasia is not specific for MDS. In the context of poor quality of bone marrow smear, very mildmorbid hematopoiesis, insignificant increase in blasts, especially a normal karyotype, the diagnosis of MDS is often challenging. Multiparameter flow cytometry has become a key tool for the diagnosis of MDS. Some studies have shown that integrated flow cytometric score (iFS) is the best scoring system for MDS diagnosis, but its use has not been reported in Chinese population.

To assess diagnostic and prognostic values of iFS in MDS to demine whether it is an appropriate flow cytometry scoring system for clinical diagnosis and prognosise valuation of MDS.

The immunophenotype data of 83 patients with MDS and 77 patients with non-MDS treated in Department of Hematology, the Affiliated People's Hospital of Ningbo University between January 2019 and April 2022 were analyzed retrospectively. Low-grade MDS was defined as less than 5% blasts in bone marrow, including MDS with single lineage dysplasia, MDS with multilineage dysplasia, MDS with ring sideroblasts, MDS, unclassifiable, and MDS with isolated del (5q). The results of chromosome karyotype and bone marrow morphology of MDS patients were collected. The probability of phenotypeabnormalities in each cell lineinterpreted according to the iFS was compared between MDS and non-MDS patients. ROC analysis was conducted to assess the performance of iFS and Ogata score in diagnosing MDS, with sensitivity, specificity and the area under the ROC curve (AUC) calculated. In the MDS group, the Spearman's rank correlation was adopted to analyze the correlation of iFS grade with cytogenetic risk category and Revised International Prognostic Scoring System (IPSS-R). The event-free survival curve was plotted by the Kaplan-Meier method and compared between MDS patients diagnosed by the iFS and the other MDS patients by Log-rank test.

MDS group had higher prevalence of phenotype abnormalities of myeloid progenitors (71.1% vs 1.3%), granulocytes/monocytes (73.5% vs 18.8%) and erythrocytes (60.2% vs 14.2%) than non-MDS group (P<0.05). The specificity and sensitivity of iFS for the diagnosis of MDS was 93.5% and 81.9%, with an AUC of 0.921〔95%CI (0.876, 0.967) 〕. And its sensitivities in diagnosing low-grade MDS and low-grade MDS with normal karyotype were 66.7% and 65.0%, respectively. The iFS grade was positively correlated with IPSS-R (r_s=0.411, P<0.05). The event-free survival of MDS patients diagnosed by the iFS was shorter than that of the other MDS patients (χ²=5.71, P<0.05) .

The iFS may compensate for morphological and cytogenetic limitations, effectively diagnose MDS and assess its prognosis, and provide clinicians with diagnostic and prognostic information on MDS.