IJCS | Volume 33, Nº4, July and August 2020

381 presence of nucleated red blood cells (NRBCs), and increases in the neutrophil-to-lymphocyte ratio (NLR) and mean platelet volume (MPV) in peripheral blood of patients hospitalized with AMI are associated with a poorer prognosis. 3 The bone marrow is responsible for producing blood cells (red blood cells, leucocytes and platelets), by a process called hematopoiesis, which originates from a single progenitor cell called the stem cell. Pluripotent stem cells, existing in small amounts in the bone marrow, can reproduce when necessary and lead to differentiation processes in different hematological cell lines. 4 Growth inducers promote multiplication but not differentiation of the stem cells. This is the function of another group of proteins, called differentiation inducers, which are controlled by factors external to the bone marrow. For example, in case of red blood cells, exposure to low oxygen concentrations over a long period results in the induction of growth, differentiation and increased production of red blood cells. This stimulus to the bone marrow is produced by erythropoietin, a glycoprotein primarily (90%) produced in the kidneys, but also in the liver, in response to hypoxemia. Prior studies have shown that severe hypoxemia and infection are the main cause of synthesis of NRBCs, and increases in NLR and MPV in peripheral blood, when hematological diseases, cancer, congestive heart failure, acute and chronic anemias are excluded. 5-13 The aim of this study was to propose a scoring system for these hematological variables. Actual and reproductive variability of these hematological biomarkers during hospitalization of these patients could be a predictor of all-cause mortality and help the medical team in diagnostic and therapeutic decision. Materials and methods Ethics Statement This study is part of the project (Neutrophil to Lymphocyte Ratio, Mean Platelet Volume and Erythroblast as prognostic biomarkers in patients with AMI) approved by the Ethics Committee of the Hospital ComplexHUOC/PROCAPE of the University of Pernambuco under number CAAE: 51802115.7.0000.5192 (Brazil Platform). The research was conducted according to the principles of the Declaration of Helsinki. Study Design The present study proposes a scoring system based on β-coefficient values estimated by multivariate logistic regression model adjusted for NRBC, MPV and NLR in patients hospitalized with AMI. In logistic model, these coefficients are obtained using the method of maximum likelihood and they represent the probabilistic change in one variable when all others are fixed. The coefficient β of each variable was multiplied by 10 to optimize the rounding. Subsequently, accuracy parameters were calculated. All patients included in the study were followed up by researchers from hospital admission to discharge. Management of these patients was established based on well-defined protocols for primary angioplasty, myocardial revascularization surgery or clinical treatment. Data on clinical course and laboratory tests of the patients were obtained daily from electronic medical records by the authors of the study. Study Population All consecutive patients admitted with AMI to PROCAPE, a tertiary teaching hospital with 250 beds, referral for emergency cardiac care, between January 1, 2016 and September 30, 2016 were included. We excluded patients younger than 18 years, on glucocorticoid therapy, patients with cancer or hematological diseases, and those readmitted after hospital discharge. All patients signed an informed consent form to participate in the study. Definition of terms and study variables The diagnosis ofAMI was established based on clinical, electrocardiographic and laboratory (troponin) criteria. 2,3 As for electrocardiography, myocardial infarction can be divided into ST-segment elevationmyocardial infarction (STEMI) and non-ST segment elevation myocardial infarction (non-STEMI). 2,3 With respect to the KILLIP and TIMI Risk scores, patients were classified into low risk (KILLIP I to II and TIMI Risk 0 to 3) and high risk (KILLIP III to IV and TIMI Risk 4 to 7). Potential risk factors associatedwithAMI such as demographic characteristics (age, gender), systemic arterial hypertension (blood pressure ≥ 140 x 90 mmHg), diabetes mellitus (plasma glucose above 126 mg/dL), smoking habit (yes or no), sedentary lifestyle (regular practice of physical exercise or not), kidney disease (creatinine above 1.3 mg/dL) and Monteiro Júnior et al. Hematological scoring system in AMI Int J Cardiovasc Sci. 2020; 33(4):380-388 Original Article