Supplementary Material for: Low Platelet Counts at Diagnosis Predict Better Survival for Patients with Intermediate-Risk Acute Myeloid Leukemia

Background: Aggressive growth of primitive and immature cells in the bone marrow results in reductions in megakaryocyte and platelet (PLT) counts, leading to thrombocytopenia in acute myeloid leukemia (AML). However, not all AML patients show thrombocytopenia at the time of diagnosis, and the association of PLT count with patient survival is largely unknown. Methods: A retrospective study was performed to determine PLT counts at diagnosis in the peripheral blood in 291 newly diagnosed AML patients and assess the association of PLT counts with the overall survival (OS) and disease-free survival (DFS) of these patients. Results: Low PLT counts (≤40 × 10⁹/L) were associated with better outcomes for the whole cohort (5-year OS, 55.1 ± 3.8 vs. 35.3 ± 3.5%, p < 0.001; 5-year DFS, 49.1 ± 3.8 vs. 25.7 ± 4.0%, p < 0.001) and intermediate-risk patients (5-year OS, 64.5 ± 5.4 vs. 41.0 ± 4.8%, p < 0.001; 5-year DFS, 60.8 ± 5.6 vs. 28.6 ± 5.6%, p < 0.001). Moreover, low PLT counts were related to deeper molecular remission. Low PLT counts correlated with better survival of intermediate-risk AML patients treated with chemotherapy only. Allogeneic hematopoietic stem cell transplantation attenuated the negative impact of high PLT counts on the survival of intermediate-risk patients. Furthermore, univariate and multivariate analyses demonstrated that PLT count at diagnosis was an independent prognostic factor for intermediate-risk AML. Conclusion: PLT count at diagnosis predicts survival for patients with intermediate-risk AML.