Fan BE, Chen DTY, Lee CY
… +14 more, Lim KGE, Ong YX, Wong WYK, Hsu SY, Chang C, Chiang PWE, Latiff STBA, Lim SP, Sum CLL, Acharyya S, Wong MS, Shanmugam H, Kuperan P, Winkler S
BACKGROUND: The peripheral blood film (PBF) analysis traditionally relies on manual microscopy (MM), a labour-intensive method with inter-observer variability. This study evaluates Blade (a semi-supervised AI model) and...BACKGROUND: The peripheral blood film (PBF) analysis traditionally relies on manual microscopy (MM), a labour-intensive method with inter-observer variability. This study evaluates Blade (a semi-supervised AI model) and CellaVision DM9600 (commercial benchmark) against MM in automated leukocyte classification. METHODS: PBFs from 168 patients were prepared using automated staining and scanned digitally. Blade, trained on 185 412 cells (75 435 labelled, 109 977 unlabelled) via ResNet34 and RetinaNet architectures, underwent pseudo-labelling and AdamW optimisation. Performance was evaluated on 1675 cells against MM using the concordance correlation coefficient (CCC), Bland-Altman analysis, Deming/Passing-Bablok regression and diagnostic accuracy measures across nine leukocyte subtypes. RESULTS: When evaluated individually against MM, both systems showed high agreement. Blade achieved excellent correlation for common cells (neutrophils: ccc = 0.988; lymphocytes: ccc = 0.985; eosinophil: ccc = 0.953) and comparable results to CellaVision for monocytes (ccc = 0.852 vs. 0.847) and basophils (ccc = 0.762 vs. 0.794). Blade performed better for metamyelocytes (ccc = 0.905 vs. 0.756) and showed higher sensitivity for monocytes (75% vs. 63%) and myelocytes (87% vs. 74%). Regression analysis showed slopes close to 1.0 for most cell types, with Blade displaying narrower Limits of Agreement in Bland-Altman analysis. Both systems achieved 100% sensitivity for blasts and reactive lymphocytes. Overall macro-averaged performance was comparable between Blade (sensitivity 89.2%, specificity 96.3%) and CellaVision (86.3% and 96.7%). CONCLUSION: Blade and CellaVision demonstrated strong concordance with MM, validating their clinical utility. Blade's semi-supervised learning confers marginal advantages in rare cell detection and stability, highlighting AI's potential to enhance diagnostic accuracy. While both systems reduce labour and variability, Blade's performance has potential for integration into haematology workflows. Future validation in diverse cohorts is recommended.
Int J Lab Hematol
· 2026 Apr · PMID 41355476
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INTRODUCTION: Point-of-care testing (POCT) for hematology enables clinicians to access actionable results during patient visits, supporting timely decisions such as transfusions or chemotherapy adjustments. However, POCT...INTRODUCTION: Point-of-care testing (POCT) for hematology enables clinicians to access actionable results during patient visits, supporting timely decisions such as transfusions or chemotherapy adjustments. However, POCT analyzers must demonstrate clinical performance comparable to centralized laboratory systems. We conducted a proof-of-concept evaluation of the HemoScreen (PixCell Medical, Israel) hematology POCT analyzer across diverse clinical settings in an integrated healthcare system. METHODS: EDTA whole blood specimens from inpatient wards, emergency departments, outpatient clinics, and infusion centers underwent routine CBC testing on a Sysmex XN analyzer (Sysmex Corporation, Japan) at the central laboratory. Residual, de-identified samples were tested within 10 min on a HemoScreen analyzer. All parameters and instrument flags were recorded. RESULTS: From 9/15/2020 to 11/20/2020, 199 samples were analyzed, including 49 from the emergency department and 50 each from inpatient, outpatient, and infusion center settings. HGB, RBC, PLT, WBC, and absolute neutrophil count showed strong linear correlations (R = 0.91-0.98) and no significant differences between instruments (p > 0.29). HCT and MCV values were significantly lower on HemoScreen (bias -5% and -3.6%; p = 0.010 and p < 0.001, respectively), with modestly reduced correlations (R = 0.80-0.89). Neutrophil percentage was higher on HemoScreen (bias +9.0%, p < 0.001), whereas monocyte counts were significantly lower (bias -50%, p < 0.001). CONCLUSION: HemoScreen demonstrated generally acceptable agreement with the Sysmex XN for most parameters. However, systematic differences in HCT, MCV, neutrophil, and monocyte results warrant further investigation to assess clinical impact before broader implementation.
BACKGROUND: Interpretation of laboratory data is a comparative process that requires reliable reference intervals (RIs) to support clinical decision-making. Although population-based reference intervals (popRIs) are comm...BACKGROUND: Interpretation of laboratory data is a comparative process that requires reliable reference intervals (RIs) to support clinical decision-making. Although population-based reference intervals (popRIs) are commonly used for this purpose, more accurate interpretation can be achieved using RIs derived from an individual's own data-that is, personalized reference intervals (prRIs). In this study, we estimated prRIs for common hematology parameters and compared them with popRIs indirectly derived from laboratory data. METHOD: popRIs were estimated for a total of 17 complete blood count (CBC) subparameters using patient laboratory data. prRIs for the same parameters were calculated using longitudinal data from 200 healthy individuals, based on a prediction interval model. Additionally, the reference interval index (RII) was calculated as the ratio of the range of prRIs to the range of popRIs for each measurand. RESULTS: prRIs calculated for CBC parameter differed from the corresponding popRIs. The median of RII varied from 0.41 for eosinophils to 2.97 for platelet distribution width (PDW). CONCLUSION: We concluded that the prRIs of the CBC parameters differ from their corresponding popRIs, and that prRIs should be used for a more accurate interpretation of patients' CBC results.
Int J Lab Hematol
· 2026 Apr · PMID 41340571
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BACKGROUND: A fixed D-dimer cut-off threshold of 0.500 μg/mL is used in Blackrock Health Hermitage Clinic (BHHC) and most Haematology laboratories across Ireland, however, international guidelines have evolved over the p...BACKGROUND: A fixed D-dimer cut-off threshold of 0.500 μg/mL is used in Blackrock Health Hermitage Clinic (BHHC) and most Haematology laboratories across Ireland, however, international guidelines have evolved over the past decade, and a growing body of evidence supports the use of age-adjusted D-dimer thresholds. This study evaluates the appropriateness of age-adjusted cut-offs in the patient population served by BHHC. Notably, inconsistent adherence to a formal hospital policy for the screening and diagnosis of venous thromboembolism (VTE) was observed throughout the clinical areas; the potential benefits of implementing such a policy are discussed herein. The integration of age-adjusted D-dimer thresholds with a validated clinical probability assessment tool may reduce unnecessary diagnostic imaging in patients investigated for VTE and prevent D-dimer testing in those deemed to have a 'likely' pre-test probability of VTE. METHODS: A cross-sectional study was conducted to determine age-related D-dimer thresholds in a representative sample of patients attending BHHC. D-dimer measurements were performed using the ACL TOP 350 coagulation analyser with HemosIL D-dimer HS 500 reagents. Statistical analysis was carried out using IBM SPSS (v29) and Microsoft Excel. Ethical approval was obtained from the BHHC Clinical Governance Committee. RESULTS: An age-related increase in D-dimer levels was observed. Applying an age-adjusted threshold (defined as patient age × 0.01 μg/mL for individuals aged 50 years and older) reduced false-positive results by 12.6% in this age group. CONCLUSION: Age-adjusted D-dimer thresholds are recommended, provided they are combined with a validated clinical probability assessment tool, such as the two-level Wells score. This approach improves diagnostic specificity and may reduce unnecessary imaging, particularly in older adults.
INTRODUCTION: Thrombin generation assay (TGA) is an assay that activates the coagulation cascade using a trigger reagent containing tissue factor (TF) and phospholipids (PL), and the generated thrombin is detected using...INTRODUCTION: Thrombin generation assay (TGA) is an assay that activates the coagulation cascade using a trigger reagent containing tissue factor (TF) and phospholipids (PL), and the generated thrombin is detected using a fluorogenic substrate. The standardisation of assay conditions and validation of in-house methods are recommended for research investigations. This study aimed to investigate the influence of TF and PL concentrations on TGA parameters in normal and abnormal plasma samples and the usefulness of commercial quality control materials for standardisation. METHODS: Five samples were employed for the TGA: Pooled Normal Plasma and Ci-Trol 1 as normal samples as well as Ci-Trol 2, Ci-Trol 3 and 2.5-fold diluted Pooled Normal Plasma. Trigger reagents were prepared with various TF and PL concentrations. The final TF concentrations were 0-50 pM with 4 μM PL, while the final PL concentrations were 0-40 μM with 5 pM TF. The lag time, peak height, time-to-peak and endogenous thrombin potential were calculated. RESULTS: The lag time and time-to-peak prolonged, and the peak height decreased as TF concentration decreased. In contrast, PL concentration primarily affected peak height. Clear thrombin peaks were confirmed in Ci-Trol 2 and Ci-Trol 3. CONCLUSIONS: Changes in TF concentration affected the lag time time-to-peak, and peak height, while alterations in PL concentration primarily affected the peak height in both normal and abnormal plasma samples. These findings are crucial for assay standardisation; Ci-Trol 2 and Ci-Trol 3 may serve as quality control materials.
INTRODUCTION: Thalassemia is a major global health concern, as declared by the World Health Organization (WHO). Accurate screening of heterozygotes is of paramount importance for diagnostic guidance and disease mitigatio...INTRODUCTION: Thalassemia is a major global health concern, as declared by the World Health Organization (WHO). Accurate screening of heterozygotes is of paramount importance for diagnostic guidance and disease mitigation. METHODS: Multiclass machine-learning (ML) models were developed to classify alpha, beta, and delta/beta-thalassemia heterozygotes, individuals with iron deficiency microcytic anemia and healthy individuals. Complete blood count (CBC) data were derived from 1518 individuals, simultaneously measured in four different hematological analyzers [Sysmex K-1000 (Sysmex), Cell-Dyn Sapphire (Abbott), ADVIA 2120 (Siemens), BC-6800 (Mindray)]. The Recursive Feature Elimination (RFE) method was applied to investigate the optimal number and combination of hematological parameters required for adequate model training, and their importance was determined using the SHAP method. Random Forest classifier and Active Learning (AL) method were used to evaluate diagnostic accuracy and enhance the model's performance, respectively. Dimensionality reduction techniques were applied for visualization purposes. Additionally, the existence of subclusters within each class was investigated using unsupervised techniques. RESULTS: Four hematological parameters (MCH, MCV, HGB, and RDW) are sufficient to classify basic types of microcytosis, achieving an accuracy of over 80%. Adding further parameters to the training process can improve the stability and reliability of the model when applied to unseen data, but does not increase test accuracy beyond 90%. Each microcytosis cluster is discriminated by assigning different weights to selected hematological parameters, forming five distinct clusters in the 2D plane (heterozygous alpha-, beta-, and delta/beta-thalassemia, iron deficiency anemia, and normal individuals). The greatest overlap between clusters occurs between alpha- and beta-thalassemia. The alpha-thalassemia cluster appears to have a more diffuse scatter on the 2D plane, but two distinct subclusters are identified within this class, characterized by the differential expression of specific parameters (PCT, MPV, P-LCR, PDW, MCV, MCH, and RBC). The developed model can estimate the probabilities of classifying a new case into the core established clusters and, in the case of alpha-thalassemia, the possible subcluster. CONCLUSION: The application of ML models for the automated differential diagnosis of microcytosis, using CBC data, revealed that the diagnostic accuracy is not proportionally dependent on the use of an increasing number of hematological parameters. A developed model is proposed which can correctly classify a new case in the core clusters or subclusters of patients with microcytosis.
Zini G, Chang YH, d'Onofrio G
… +8 more, Frater J, Germing U, Merino A, Pozdnyakova O, Ross D, Filho CRS, Takami A, Wendy E
Int J Lab Hematol
· 2026 Feb · PMID 41297912
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Monocytes are key components of the Mononuclear Phagocyte System, crucial in immune defense, inflammation, and tissue repair. Accurate identification and classification of monocyte lineage cells are essential for diagnos...Monocytes are key components of the Mononuclear Phagocyte System, crucial in immune defense, inflammation, and tissue repair. Accurate identification and classification of monocyte lineage cells are essential for diagnosing both reactive and clonal hematologic disorders. However, morphological criteria and nomenclature inconsistencies have hindered reproducibility, particularly with the rise of automated and AI-driven diagnostic tools. The International Council for Standardization in Haematology (ICSH) Monocyte Working Group (MWG) was convened to establish standardized morphological definitions, harmonize nomenclature for monocytes and their precursors, and evaluate their clinical utility as biomarkers. Data were collected from global laboratories, combined with an extensive literature review and consensus feedback from the ICSH General Assembly. The MWG proposes a three-category morphological classification: blasts and blast equivalents (monoblasts and promonocytes), immature monocytes, and mature monocytes. The recommendations reaffirm the importance of morphological analysis, cytochemical staining, and flow cytometry for accurate diagnosis. Emerging automated parameters, such as monocyte distribution width (MDW), and ratios like lymphocyte/monocyte (LMR) and neutrophil/monocyte (NMR), are also recognized as valuable adjunctive biomarkers. Cytogenetic and molecular results may also impact the utilization of monocytes as a biomarker. These harmonized recommendations aim to improve diagnostic accuracy, support the development of machine learning tools, and facilitate consistent reporting across laboratories worldwide.
De Maria L, Baldini L, Mouanes Abelin J
… +4 more, Ferrero C, Boursier Y, Berda-Haddad Y, Toulon P
Int J Lab Hematol
· 2026 Apr · PMID 41285154
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OBJECTIVES: The all-trans-retinoic acid (ATRA) treatment used in acute promyelocytic leukemia (APL) has the particularity of inducing differentiation of the leukemia cells. As a result, within the same smear, several sta...OBJECTIVES: The all-trans-retinoic acid (ATRA) treatment used in acute promyelocytic leukemia (APL) has the particularity of inducing differentiation of the leukemia cells. As a result, within the same smear, several stages of cellular differentiation of the granular lineage are present, which can make it difficult to distinguish elements when counting cells. METHODS: The aim of this study is to use the technical data from Sysmex haematology equipment in patients with APL to improve their cytological monitoring and harmonize blood count results from one operator to another. We collected 132 samples from patients with APL over a period of 45 days from the day of diagnosis and divided them into two groups: presence or absence of blast cells on the blood smear. RESULTS: Seven parameters of leukocyte subpopulations were selected for cytological monitoring. We developed a decision algorithm based on these, including decision thresholds for predicting the presence or absence of blasts. These data were verified on a validation cohort of 110 samples with APL, set up at a different site from the training cohort. The algorithm predicted the presence of blast cells in these samples with a sensitivity of 84.6% and a specificity of 86.7%. CONCLUSION: In the context of cytological monitoring of patients with APL, the study of technical data has not been developed yet, despite the fact that this is a difficult and sometimes nonhomogeneous task from one operator to another. The proposed algorithm could be a facilitating tool in cytology to harmonize practices both within and between sites.
da Silva FRM, Vizzoni AG, Mendes-de-Almeida D
… +5 more, Bokel J, Oliveira RVC, Siqueira AM, Vieira YR, da Costa Cruz Silva S
Int J Lab Hematol
· 2026 Apr · PMID 41276984
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BACKGROUND: G6PD deficiency affects about 500 million people worldwide and is prevalent in many malaria-endemic settings. People with G6PD deficiency are at risk of hemolysis when exposed to certain medications, includin...BACKGROUND: G6PD deficiency affects about 500 million people worldwide and is prevalent in many malaria-endemic settings. People with G6PD deficiency are at risk of hemolysis when exposed to certain medications, including 8-aminoquinoline drugs used to treat Plasmodium vivax malaria. Increasing access to testing for G6PD deficiency at or near the point of care is critical to expanding the safe treatment of P. vivax malaria. We aimed to evaluate the performance of a semiquantitative test for G6PD deficiency, the SD Biosensor Standard G6PD Test with the Brewer's method, in a reference site for the treatment of infectious diseases. METHOD: We evaluate the diagnostic accuracy performance of the SD Biosensor Standard G6PD Test in 125 individuals with infectious diseases and other illnesses. MAIN RESULTS: We observed a trend of concordance between the G6PD status (Deficient or Normal), with low frequencies of discordances in the screenings. The strength of agreement between G6PD tests was classified as almost perfect in all participants (k = 0.82, 95% CI = 0.66, 0.97) and in sex subgroups: females (k = 0.83, 95% CI = 0.59, 1.00) and males (k = 0.81, 95% CI = 0.59, 1.00). The total concordance percentage (number of concordances/total) was 95% for females, 97% for males, and 96% overall. CONCLUSION: The SD Biosensor STANDARD G6PD test is an innovative point-of-care solution. It offers quantitative measurement of glucose-6-phosphate dehydrogenase activity while normalizing for hemoglobin levels. This advancement enables its use in lower-tier clinical and laboratory settings, expanding access to accurate G6PD testing.
INTRODUCTION: This study provides a comprehensive verification and comparative evaluation of four hematology analyzers (HA) with a five-part differential blood count (5-DIFF) (Siemens Advia 2120i, Sysmex XN-1000, Mindray...INTRODUCTION: This study provides a comprehensive verification and comparative evaluation of four hematology analyzers (HA) with a five-part differential blood count (5-DIFF) (Siemens Advia 2120i, Sysmex XN-1000, Mindray BC-5310CRP, Beckman Coulter DxH 900). METHODS: The parameters of complete blood count (CBC) with 5-DIFF were examined. The verification protocol assessed precision, accuracy, linearity, limits of blank (LoB), detection (LoD) and quantification (LoQ), and carryover. Advia 2120i served as the reference HA for accuracy assessment. Statistical analysis was performed using MedCalc and MS Excel. Acceptance criteria followed manufacturer specifications and biological variability analytical performance specifications (APS). RESULTS: All analyzers showed acceptable precision for most CBC parameters, while XN-1000 and DxH 900 showed the best repeatability. BC-5310 CRP showed the highest proportion of parameters exceeding acceptance criteria: low leukocytes in control (2.9%), and low platelets (6.1%) as well as low (16.4%) and high (4.1%) leukocytes in patient samples. Advia 2120i showed suboptimal repeatability at low hemoglobin in control (53 g/L, CV 1.1%) and low leukocytes (4.7%) for patient samples. Platelet repeatability varied most (CV 5.4%-9.7%). Platelet accuracy was significantly different on XN-1000 (p = 0.04) and BC-5310CRP (p = 0.05). Determined LoQ for leukocytes were: 0.1 (Advia 2120i) and 0.3 × 10/L (XN-1000, BC-5310CRP, DxH 900). LoQ for platelets: 3 (Advia 2120i), 4 (XN-1000), 5 (DxH 900), and 10 × 10/L (BC-5310CRP). Linearity was confirmed for all, wherein Mindray had slightly wider 95%-CI. No carryover was observed. CONCLUSION: While all analyzers demonstrated acceptable performance for the majority of evaluated specifications, Sysmex XN-1000 and Beckman Coulter DxH 900 achieved the most favorable overall performance.
Soulard M, Ketatni H, Croix P
… +2 more, Wuilleme S, Cohen P
Int J Lab Hematol
· 2026 Apr · PMID 41239905
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INTRODUCTION: We investigated the stability and accuracy of platelets with MgSO and compared the results of blood counts between MgSO and K2EDTA. METHODS: Platelet stability as a function of time was assessed on the XN S...INTRODUCTION: We investigated the stability and accuracy of platelets with MgSO and compared the results of blood counts between MgSO and K2EDTA. METHODS: Platelet stability as a function of time was assessed on the XN Sysmex analyzer by comparing the percentage deviation to the desirable bias of the EFLM. Accuracy was determined by calculating the LoQ of platelets corresponding to a CV of 10%. Results from 250 patients were compared between K2EDTA and MgSO. RESULTS: At 20°C, platelets were stable for 24 h in impedance, 10 h in fluorescence and at 4°C for 4 h in impedance, 2 h in fluorescence. This decrease is related to the formation of platelet aggregates. For platelets in fluorescence, LoQ is 4 × 10/L using MgSO. The results of the complete blood count did not differ between K2EDTA and MgSO except for the MCV, for which the median relative bias (MRB) with respect to K2EDTA was -5.6%. For MgSO platelets, the MRB is 2.9% in fluorescence and 11.9% in impedance. CONCLUSION: The use of MgSO with the XN produces results comparable to those obtained with K2EDTA, except for those related to MCV and for impedance platelets.
Al Dawood R, Sabah HA, Mathews N
… +2 more, Douketis J, Hayward C
Int J Lab Hematol
· 2026 Apr · PMID 41235688
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INTRODUCTION: D-dimers are produced by lysis of cross-linked fibrin. In children, D-dimer testing is used to evaluate disseminated intravascular coagulation (DIC) and some inflammatory states, but its use is not validate...INTRODUCTION: D-dimers are produced by lysis of cross-linked fibrin. In children, D-dimer testing is used to evaluate disseminated intravascular coagulation (DIC) and some inflammatory states, but its use is not validated for screening or ruling out suspected venous thromboembolic events (VTE). In adults, D-dimers are used to evaluate DIC, and a low D-dimer level is used to exclude VTE in patients when combined with a low or moderate probability of VTE. METHODS: To assess D-dimer utilization and opportunities for improvement, we conducted a retrospective, consecutive-case cohort study (with ethics approval) of patients who had D-dimer tests at Hamilton hospitals, from 06/2022 to 05/2023. RESULTS: D-dimer levels were evaluated for 175 children and 200 adults (respective results, children/adults: median ages: 12/63, ranges 0-17/18-94 years), and an overlapping cohort of 99 consecutive persons with ≥ 5 D-dimer determinations. Most patients had D-dimer tests in emergency departments (60%/62%) and elevated D-dimer levels (55%/61%). Reasons for D-dimer assessment included: suspected VTE (50%/70%), DIC (17%/3.5%), childhood inflammatory conditions (23%/0%), and "off-label" uses (e.g., arterial thrombosis assessment; 5%/22%). VTE likelihood and DIC scores were rarely documented. Patients with multiple tests accounted for 15% of D-dimer workload. Among patients with multiple tests for DIC, most had overt DIC on initial assessment, with declining D-dimer levels over 10-14 days, including patients who died. CONCLUSION: VTE and DIC assessment was the most common reason for D-dimer assessments for children and adults. Quality improvement initiatives are needed to improve relevant clinical VTE and DIC score documentation and D-dimer test utilization.
INTRODUCTION: Numerous algorithms based on recent developments of additional parameters on last generation haematology analysers have opened new perspectives for hereditary spherocytosis (HS) screening. Although some stu...INTRODUCTION: Numerous algorithms based on recent developments of additional parameters on last generation haematology analysers have opened new perspectives for hereditary spherocytosis (HS) screening. Although some studies have demonstrated significant age-related variation for reticulocyte-derived parameters, these algorithms did not consider patients' age. Moreover, the apparent lack of short-term stability of some parameters could represent an obstacle to their use if not performed as first-line testing. This study aimed to identify robust and discriminating parameters that could be used for HS screening at any patients' age. METHODS: After an evaluation of the reference values and stability of the additional parameters offered by the Sysmex XN-9000, we retrospectively collected and analysed the haematological parameters of 103 confirmed HS patients and 124 controls. The HS group was also compared to 116 samples from patients affected with other red blood cell or iron disorders. RESULTS: Our findings confirm that the reticulocyte count (Ret) and its ratio to the immature reticulocyte fraction (Ret/IRF) are the most effective and robust parameters for HS screening, with stability up to 48 and 96 h at room temperature (RT) and 4°C, respectively. The Ret/IRF ratio was mostly affected by patients' age rather than haemoglobin levels. We therefore proposed different algorithms that can be adapted to the laboratory's needs and that incorporate age-specific thresholds for Ret/IRF. The combination of Ret and Ret/IRF allowed a sensitivity between 91.3% and 100% and a specificity between 77.1% and 94.2%. CONCLUSIONS: This new age-dependent algorithm using Sysmex's most stable parameters offers an easy-to-use tool for HS screening, even in cases of delayed or residual blood analysis.
INTRODUCTION: Thrombosis is a leading cause of mortality in polycythemia vera (PV), yet little is known about early predictors of thrombosis progression. Emerging evidence links systemic inflammation to thrombosis risk....INTRODUCTION: Thrombosis is a leading cause of mortality in polycythemia vera (PV), yet little is known about early predictors of thrombosis progression. Emerging evidence links systemic inflammation to thrombosis risk. This study assessed hematological inflammatory parameters, including the neutrophil-to-lymphocyte ratio (NLR), monocyte-to-lymphocyte ratio (MLR), platelet-to-lymphocyte ratio (PLR), systemic immune-inflammation index (SII), systemic inflammatory response index (SIRI), and aggregate index of systemic inflammation (AISI), for their utility in predicting thrombosis progression in PV. METHODS: This retrospective study analyzed 102 PV patients (2008-2024) and 115 healthy controls. Clinical and laboratory data, including thrombotic events, were examined. Patients were stratified into low-and high-risk groups, further categorized by thrombosis progression. Inflammatory biomarkers were derived from baseline blood counts. RESULTS: Median follow-up was 51 months, the 10-year thrombotic events-free survival rate was 84.30%, and 21 patients (20.59%) showed thrombosis progression. PV patients had higher NLR, MLR, PLR, SII, SIRI, and AISI than controls. NLR, MLR, SIRI, and AISI were associated with an increased risk of thrombosis compared to the low-risk group. In the progression group, high monocytes, NLR, MLR, SIRI, AISI, and previous thrombosis were notably correlated. ROC analysis showed that MLR (AUC = 0.739), SIRI (AUC = 0.714), AISI (AUC = 0.670), and NLR (AUC = 0.649) had the highest predictive ability for thrombosis progression. Multivariate analysis identified MLR (HR = 6.979) and previous thrombosis (HR = 4.494) as independent risk factors. CONCLUSION: These findings support recent reports linking systemic inflammation to thrombosis risk in PV patients and highlight for the first time that MLR may serve as a valuable prognostic biomarker for thrombotic events.