Individualized dose of anti-thymocyte globulin based on weight and pre-transplantation lymphocyte counts in pediatric patients: a single center experience.

Anti-thymocyte globulin (ATG) has become a standard in preventing GVHD in related and unrelated donor transplantation, but there is no consensus on the best administration schedule. The PARACHUTE trial reported excellent CD4 immune reconstitution (CD4 IR) using a dosing schedule based on the patient's weight and pre-conditioning absolute lymphocyte count (ALC). In 2015 we introduced the PARACHUTE dosing schedule for pediatric patients at our center. One hundred one patients were transplanted for malignant and non-malignant diseases. In this non-concurrent cohort CD4 IR+, defined by a single CD4 count >50/µL on day 90, was seen in 81% of patients. The incidence of grade II-IV and III to IV aGvHD was 26.6% and 15.3% and 5% for cGvHD with no severe cases. We found no difference in aGvHD between donor type and stem cell sources. Five-year EFS and OS were 77.5% and 83.5%. Grade III-IV GFRS was 75.2%. CD4 IR+ patients had better EFS (93.1% vs. 77.7%, p = 0.04) and lower non-relapse mortality (2.7% vs. 22.2%, p = 0.002). The PARACHUTE ATG dosing schedule individualized by weight and ALC results in good early immune reconstitution, low incidence of cGvHD, and favorable survival for patients with different disease groups, donor types, and stem cell sources.

American Society of Hematology, ABHH, ACHO, Grupo CAHT, Grupo CLAHT, SAH, SBHH, SHU, SOCHIHEM, SOMETH, Sociedad Panamena de Hematología, Sociedad Peruana de Hematología, and SVH 2023 guidelines for diagnosis of venous thromboembolism and for its management in special populations in Latin America.

Implementation of international guidelines in Latin American settings requires additional considerations (ie, values and preferences, resources, accessibility, feasibility, and impact on health equity). The purpose of this guideline is to provide evidence-based recommendations about the diagnosis of venous thromboembolism (VTE) and its management in children and during pregnancy. We used the GRADE ADOLOPMENT method to adapt recommendations from 3 American Society of Hematology (ASH) VTE guidelines (diagnosis of VTE, VTE in pregnancy, and VTE in the pediatric population). ASH and 12 local hematology societies formed a guideline panel comprising medical professionals from 10 countries in Latin America. Panelists prioritized 10 questions about the diagnosis of VTE and 18 questions about its management in special populations that were relevant for the Latin American context. A knowledge synthesis team updated evidence reviews of health effects conducted for the original ASH guidelines and summarized information about factors specific to the Latin American context. In comparison with the original guideline, there were significant changes in 2 of 10 diagnostic recommendations (changes in the diagnostic algorithms) and in 9 of 18 management recommendations (4 changed direction and 5 changed strength). This guideline ADOLOPMENT project highlighted the importance of contextualizing recommendations in other settings based on differences in values, resources, feasibility, and health equity impact.

Crown-Root Angle Measurement in Permanent Central Incisors

The anatomical variations of teeth are directly related to the esthetics achieved in orthodontic treatment. These variations include the dental axes, such as the long crown axis and the long root axis. For this reason, these axes and the angle formed by their intersection, or crown-root angle, have been studied using several methodologies, mainly in central incisors. This study aimed to propose the visual- spatial processing as a method to determine the long crown axis and the long root axis, and thus measure the angle between these axes (crown-root angle) in the permanent upper and lower central incisors. The study had a quantitative, descriptive, observational and cross- sectional approach. The study sample consisted of 100 Cone-beam computed tomography (CBCT) images: 50 of permanent upper central incisors and 50 of permanent lower central incisors. The crown-root angle was measured considering the long crown axis and the long root axis. The mean crown root angle in the upper central incisors was 21.34 °, with a standard deviation (SD) of 4.41º; for the lower central incisors, the mean value was 20.05º with a SD of 4.18º. This study suggests that the visual-spatial processing can be a valid method to determine the long crown axis and the long root axis, also with the advantage of not requiring specific instruments and anatomical reference points, which simplifies the tracing of axes and thus measurement of the crown-root angle.

Las variaciones anatómicas de los dientes tienen directa relación con la estética lograda en el tratamiento de ortodoncia. Dentro de estas variaciones se encuentran los ejes dentarios, como el eje mayor de la corona y el eje mayor radicular. Por esta razón, se ha estudiado mediante diversas metodologías estos ejes y el ángulo formado por dicha intersección o ángulo corono radicular, principalmente en los incisivos centrales. El objetivo del presente estudio es plantear la percepción viso espacial como método para determinar el eje mayor de la corona y el eje mayor radicular, y así medir el ángulo entre estos ejes (ángulo corono radicular) en los incisivos centrales superiores e inferiores definitivos. La investigación es de enfoque cuan- titativo, descriptivo, observacional y transversal. La muestra del estudio fueron 100 imágenes de CBCT: 50 de incisivos centrales superiores definitivos y 50 de incisivos centrales inferiores definitivos. Se midió el ángulo corono radicular considerando el eje mayor de la corona y el eje mayor radicular. El promedio del ángulo corono radicular en los incisivos centrales superiores fue de 21.34° con desviación estándar (DS) de 4. 41º y para los incisivos centrales inferiores se obtuvo como valor promedio 20.05º con DS de 4.18º. Este estudio plantea que la percepción viso espacial puede ser válido como método para determinar el eje mayor de la corona y el eje mayor radicular, teniendo además la ventaja de prescindir de instrumentos específicos y de puntos anatómicos de referencia, lo cual simplifica el trazado de los ejes y por ende la medición del ángulo corono radicular.

American Society of Hematology, ABHH, ACHO, Grupo CAHT, Grupo CLAHT, SAH, SBHH, SHU, SOCHIHEM, SOMETH, Sociedad Panamena de Hematología, Sociedad Peruana de Hematología, and SVH 2023 guidelines for diagnosis of venous thromboembolism and for its management in special populations in Latin America

Implementation of international guidelines in Latin American settings requires additional considerations (ie, values and preferences, resources, accessibility, feasibility, and impact on health equity). The purpose of this guideline is to provide evidence-based recommendations about the diagnosis of venous thromboembolism (VTE) and its management in children and during pregnancy. We used the GRADE ADOLOPMENT method to adapt recommendations from 3 American Society of Hematology (ASH) VTE guidelines (diagnosis of VTE, VTE in pregnancy, and VTE in the pediatric population). ASH and 12 local hematology societies formed a guideline panel comprising medical professionals from 10 countries in Latin America. Panelists prioritized 10 questions about the diagnosis of VTE and 18 questions about its management in special populations that were relevant for the Latin American context. A knowledge synthesis team updated evidence reviews of health effects conducted for the original ASH guidelines and summarized information about factors specific to the Latin American context. In comparison with the original guideline, there were significant changes in 2 of 10 diagnostic recommendations (changes in the diagnostic algorithms) and in 9 of 18 management recommendations (4 changed direction and 5 changed strength). This guideline ADOLOPMENT project highlighted the importance of contextualizing recommendations in other settings based on differences in values, resources, feasibility, and health equity impact.

[Monitoring of anticoagulant treatment with Unfractionated Heparin in pediatrics]. / Monitoreo del tratamiento anticoagulante con Heparina no Fraccionada en pediatría.

Unfractionated heparin (UFH) is the most widely used anticoagulant in hospitalized patients. The therapeutic range (TR) was defined in adults according to the prolongation of the activated Partial Thromboplastin Time (aPTT). However, the recommendation is to maintain a therapeutic range with anti-factor Xa assay (antiFXa). As this technique is more complex to perform and less available, it is recommended to make local correlation curves of aPTT with antiFXa. OBJECTIVE: to determine the correlation between the values of aPTT and antiFXa in patients treated with UFH. PATIENTS AND METHOD: 52 patients between 2 days to 14 years of age hospitalized in the Pediatric Critical Patient Unit were recruited. They received treatment with UFH in continuous infusion for at least 24 hours. aPTT and antiFXa tests were performed according to the moment of anticoagulation. To evaluate the concordance of the levels of aPTT with those of antiFXa, the Kappa statistical coefficient of Landis and Koch was used. RESULTS: 105 samples were collected from 52 patients. The overall concordance was 0.452 (moderate correlation). In patients aged < 1 month (n = 40), a considerable correlation was evident (r = 0.617); in those from 1 month to < 6 months (n = 18) and 6 months - < 12 months with aPTT < 120 seconds (n = 11), also showed a considerable correlation (r = 0.636 and 0.615, respec tively), while in those aged > 12 months (n = 37) with aPTT < 120 seconds, a moderate correlation was evident (r = 0.454). CONCLUSION: In our population, there is a moderate correlation between the values of aPTT and antiFXa.

Maternal and perinatal outcomes of a venous thromboembolism high-risk cohort using a multidisciplinary treatment approach.

OBJECTIVE: To evaluate the maternal and perinatal outcomes in a cohort of pregnant women at high risk of venous thromboembolism (VTE). METHODS: Women at high risk of VTE were evaluated in a multidisciplinary program using a complete diagnostic workup, and specific prophylactic or therapeutic treatment. RESULTS: Women were considered at high risk of VTE in 57% (85/148) because of prior (75) or current (10) thromboembolism, and in 27% (40/148) of the cases due to adverse obstetric history. Thrombophilia was diagnosed in 57% of the cases (85/148), either in patients with previous thromboembolism (48%, 41/85) or without a history of thrombosis (70%, 44/63). The most common thrombophilia was antiphospholipid syndrome in 34% (29/85) of the cases. Under respective prophylactic or therapeutic treatment, there were no VTE during pregnancy (0%, 0/148), whereas four events occurred during the puerperium (3%, 4/148). An adverse obstetric outcome was present in 5% (7/148) of all pregnancies, with four early spontaneous abortions (3%, 4/148) and three late miscarriages (2%, 3/148). CONCLUSION: Pregnant women at high risk of VTE can be effectively managed using a risk-adapted treatment. Our results support prospective enrollment and a multidisciplinary assessment of VTE in high-risk pregnant women.

Asociación entre enfermedad de von Willebrand y angiodisplasia: ¿casualidad o causalidad?

Von Willebrand factor (vWf) is a fundamental multimeric plasma glycoprotein in the coagulation process. Its function is to mediate platelet adhesion and to stabilize circulating factor VIII. A functional or quantitative alteration of vWf gives rise to von Willebrand disease (vWD). The association between vWD and angiodysplasia was described in 1967, but it was only until 2011 that Starke et al demonstrated the in vitro and in vivo role of vWf in angiogenesis. Congenital or acquired vWf deficiency, especially of high molecular weight multimeters, not only favors bleeding, but also contributes to increased angiogenesis in these patients. The treatment should be focused both on the control of the acute episode of gastrointestinal bleeding, with vWf replacement therapy and local endoscopic treatment, as well as on the prevention of the progression of angiodysplasia and future bleeding. There are different published therapeutic approaches using vWf replacement that are not effective in all patients. Recently, angiogenesis inhibitor medications have been used.

[Association between von Willebrand disease and angiodysplasia]. / Asociación entre enfermedad de von Willebrand y angiodisplasia: ¿casualidad o causalidad?

Von Willebrand factor (vWf) is a fundamental multimeric plasma glycoprotein in the coagulation process. Its function is to mediate platelet adhesion and to stabilize circulating factor VIII. A functional or quantitative alteration of vWf gives rise to von Willebrand disease (vWD). The association between vWD and angiodysplasia was described in 1967, but it was only until 2011 that Starke et al demonstrated the in vitro and in vivo role of vWf in angiogenesis. Congenital or acquired vWf deficiency, especially of high molecular weight multimeters, not only favors bleeding, but also contributes to increased angiogenesis in these patients. The treatment should be focused both on the control of the acute episode of gastrointestinal bleeding, with vWf replacement therapy and local endoscopic treatment, as well as on the prevention of the progression of angiodysplasia and future bleeding. There are different published therapeutic approaches using vWf replacement that are not effective in all patients. Recently, angiogenesis inhibitor medications have been used.

Validez estructural de la Escala de Apoyo Social en el Trabajo en peruanos / Structural validation of Social Support at Work Scale in Peruvians

INTRODUCCIÓN Y OBJETIVOS: El presente estudio obtuvo las primeras evidencias de la validez de la estructura interna e invarianza de la Escala de Apoyo Social en el Trabajo, una medida integrada en la batería de pruebas UNIPSICO para la evaluación de factores psicosociales de los recursos. MATERIAL Y MÉTODO: Participaron 177 ingenieros (74% varones) de 19 a 64 años provenientes de la ciudad de Lima, Perú. Se examinó la estructura interna mediante 2 modelamientos: el enfoque no paramétrico de la Teoría de Respuesta al Ítem y el modelamiento SEM; se probó el funcionamiento diferencial de ítems según el sexo y la confiabilidad fue estimada con los coeficientes alfa de Cronbach y Omega. RESULTADOS: Se verificó una fuerte estructura unidimensional de la Escala de Apoyo Social en el Trabajo con ambos enfoques (cargas factoriales entre .46 y .82); no se detectó funcionamiento diferencial respecto al sexo y los coeficientes de la confiabilidad fueron aceptables y muy similares (.79). CONCLUSIONES: La Escala de Apoyo Social en el Trabajo presenta resultados satisfactorios en cuanto a validez y confiabilidad y apertura hacia futuras investigaciones en el contexto peruano

INTRODUCTION AND OBJECTIVES: This study obtained preliminary evidence for the validity of the internal structure and invariance of the Social Support at Work Scale, an integrated measure in the battery of UNIPSICO tests for the evaluation of psychosocial factors of resources. MATERIAL AND METHOD: 177 engineers participated (74% males) aged 19 to 64 years old from the city of Lima, Peru. The internal structure was examined through two models: the nonparametric approach of the Item Response Theory and SEM modeling; the differential functioning of items according to sex was tested and the reliability was estimated with Cronbach's alpha and Omega coefficients. RESULTS: A strong one-dimensional structure of the Social Support at Work Scale was verified with both approaches (factor loads between .46 and .82); no differential functioning was detected with respect to sex and the reliability coefficients were acceptable and very similar (.79). CONCLUSIONS: The Social Support at Work Scale presents satisfactory results in terms of validity and reliability and opens the door to future research in the Peruvian context

[Liver transplantation in hemophilia A. Report of one case]. / El trasplante de hígado es un procedimiento plausible, efectivo y seguro en pacientes con hemofilia. Caso clínico.

Due to blood derivative requirements, many patients with hemophilia were exposed to Hepatitis C virus infection (HCV) before the availability of HCV testing. We report a 46-year-old male with Hemophilia A with a hepatitis virus C infection since 2004 causing a cirrhosis. Due to a hepatopulmonary syndrome, he received a liver allograph using a factor VIII replacement protocol, after eradicating the virus C. He had a good postoperative evolution, and no more factor VIII was required after transplantation until his last assessment.

El trasplante de hígado es un procedimiento plausible, efectivo y seguro en pacientes con hemofilia: caso clínico / Liver transplantation in hemophilia A: report of one case

Due to blood derivative requirements, many patients with hemophilia were exposed to Hepatitis C virus infection (HCV) before the availability of HCV testing. We report a 46-year-old male with Hemophilia A with a hepatitis virus C infection since 2004 causing a cirrhosis. Due to a hepatopulmonary syndrome, he received a liver allograph using a factor VIII replacement protocol, after eradicating the virus C. He had a good postoperative evolution, and no more factor VIII was required after transplantation until his last assessment.

El sangrado menstrual excesivo afecta la calidad de vida en adolescentes / Heavy menstrual bleeding affects quality of life in adolescents

Resumen Introducción: El sangrado menstrual excesivo (SME) se presenta aproximadamente en 37% de las adolescentes y afecta en distinto grado su calidad de vida. Objetivo: Medir la magnitud del impacto del SME en la calidad de vida en adolescentes. Pacientes y Método: Se entrevistó a adolescentes con diagnóstico de SME entre 10 y 18 años y a uno de sus tutores. Se aplicó el cuestionario de calidad de vida PedsQL 4.0 escala genérica, su versión Proxy PedsQL 4.0 al tutor, más 3 preguntas sobre limitación de actividades diarias. La concordancia entre la percepción de calidad de vida del tutor y adolescente se evaluó con el gráfico de Bland y Altman. Resultados: 46 adolescentes y tutores fueron evaluados. El puntaje total promedio PedsQL 4.0 para las adolescentes fue 64,48 (DS 14,54), con un rango de 18,48 a 88,04 con mayor compromiso en la dimensión emocional. Un 50% de las adoles centes falta al colegio, 80,4% a educación física y 65,2% a actividades al aire libre o fiestas. No hubo concordancia entre la percepción de las adolescentes y sus tutores. Conclusiones: Se evidenció un deterioro de la calidad de vida de las adolescentes encuestadas, siendo la dimensión emocional la más afectada. El desempeño en el cuestionario fue incluso más bajo que en patologías crónicas publicadas con esta misma herramienta.

Abstract Introduction: Heavy menstrual bleeding (HMB) occurs in 37% of adolescents and compromise their quality of life. Objective: To measure the magnitude of the impact of the SME on the quality of life in adolescents. Patients and Method: We interviewed adolescents diagnosed with HMB between 10 and 18 years old and one of their guardians. PedsQL 4.0 generic core scale was applied to measure quality of life, its Proxy PedsQL 4.0 version was applied to the guardian and 3 more questions to adolescents about limitation of daily activities. The concordance between the guardian's perception of the adolescent quality of life and the adolescent's perception was evaluated with the Bland and Altman graph. Results: 46 adolescents and guardians were evaluated. The total average PedsQL 4.0 score for adolescents was 64.48 (SD 14.54), with a range of 18.48 to 88.04 with a greater involvement in the emotional dimension. 50% of adolescents missed school, 80.4% physical education and 65.2% outdoor activities or parties. There was no agreement between the perception of the girls and guar dians. Conclusions: We evidence a deterioration in the quality of life of the surveyed adolescents, being the emotional dimension most affected. The performance in the questionnaire was also lower than in samples of chronic diseases published with this same tool.

Bleeding risk of surgery and its prevention in patients with inherited platelet disorders.

Excessive bleeding at surgery is a feared complication in patients with inherited platelet disorders. However, very few studies have evaluated the frequency of surgical bleeding in these hemorrhagic disorders. We performed a worldwide, multicentric, retrospective study to assess the bleeding complications of surgery, the preventive and therapeutic approaches adopted, and their efficacy in patients with inherited platelet disorders: the Surgery in Platelet disorders And Therapeutic Approach (SPATA) study. We rated the outcome of 829 surgical procedures carried out in 423 patients with well-defined forms of inherited platelet disorders: 238 inherited platelet function disorders and 185 inherited platelet number disorders. Frequency of surgical bleeding was high in patients with inherited platelet disorders (19.7%), with a significantly higher bleeding incidence in inherited platelet function disorders (24.8%) than in inherited platelet number disorders (13.4%). The frequency of bleeding varied according to the type of inherited platelet disorder, with biallelic Bernard Soulier syndrome having the highest occurrence (44.4%). Frequency of bleeding was predicted by a pre-operative World Health Organization bleeding score of 2 or higher. Some types of surgery were associated with a higher bleeding incidence, like cardiovascular and urological surgery. The use of pre-operative pro-hemostatic treatments was associated with a lower bleeding frequency in patients with inherited platelet function disorders but not in inherited platelet number disorders. Desmopressin, alone or with antifibrinolytic agents, was the preventive treatment associated with the lowest bleedings. Platelet transfusions were used more frequently in patients at higher bleeding risk. Surgical bleeding risk in inherited platelet disorders is substantial, especially in inherited platelet function disorders, and bleeding history, type of disorder, type of surgery and female sex are associated with higher bleeding frequency. Prophylactic pre-operative pro-hemostatic treatments appear to be required and are associated with a lower bleeding incidence.

[Heavy menstrual bleeding affects quality of life in adolescents]. / El sangrado menstrual excesivo afecta la calidad de vida en adolescentes.

INTRODUCTION: Heavy menstrual bleeding (HMB) occurs in 37% of adolescents and compromise their quality of life. OBJECTIVE: To measure the magnitude of the impact of the SME on the quality of life in adolescents. PATIENTS AND METHOD: We interviewed adolescents diagnosed with HMB between 10 and 18 years old and one of their guardians. PedsQL 4.0 generic core scale was applied to measure quality of life, its Proxy PedsQL 4.0 version was applied to the guardian and 3 more questions to adolescents about limitation of daily activities. The concordance between the guardian's perception of the adolescent quality of life and the adolescent's perception was evaluated with the Bland and Altman graph. RESULTS: 46 adolescents and guardians were evaluated. The total average PedsQL 4.0 score for adolescents was 64.48 (SD 14.54), with a range of 18.48 to 88.04 with a greater involvement in the emotional dimension. 50% of adolescents missed school, 80.4% physical education and 65.2% outdoor activities or parties. There was no agreement between the perception of the girls and guar dians. CONCLUSIONS: We evidence a deterioration in the quality of life of the surveyed adolescents, being the emotional dimension most affected. The performance in the questionnaire was also lower than in samples of chronic diseases published with this same tool.

Factors associated with thrombotic complications in pediatric patients with vascular malformations.

BACKGROUND AND OBJECTIVES: Thrombosis is an uncommon disorder in children. Patients with slowflow vascular malformations have higher risk of developing localized intravascular coagulation, which is closely related to the presence of thrombotic events. These episodes cause pain, can be recurrent and determine a clear deterioration in the quality of life. Moreover, serious complications such as pulmonary thromboembolism and eventually death have been described. The aim of the present study is to identify clinical and laboratory risk factors associated with thrombotic events in pediatric patients with vascular malformations. METHODS: Case-Control study. Clinical records of patients who consulted the vascular anomalies study group (VASG). This group carries out interdisciplinary assessment of patients with vascular malformations. From June 2008 to December 2014, 110 patients were assessed of whom 46 patients met the inclusion criteria, with half of them presenting a thrombotic complication and the others not, these latter serving as controls. Statistical analysis included multivariate logistic regression analysis to determine major risk factors for thrombosis. RESULTS: In the bivariate analysis we found a significant association between increased levels of Ddimer and thrombotic complications (OR 17.1 [95% CI 3.95-73.95; p<0.01]). In addition, a surface area≥10cm2 (OR 6.18 [95% CI 1.59-23.99; p<0.01]) and the presence of palpable phleboliths (OR 20.17 [95% CI 2.32-165.77; p<0.01]) were associated with a significant higher risk of thrombosis. Multivariate analysis identified older age (OR 1.33; p=0.013), a surface area≥10cm2 (OR 8.19; p=0.042) and palpable phleboliths (OR 85.29; p<0.01) as significant risk factors. CONCLUSIONS: Our study suggests the existence of clinical factors associated with higher risk of thrombotic complications, such as the extent of the malformation, palpable phleboliths and increased age among children with vascular malformations.

Prediction of Esophageal Variceal Bleeding in Liver Cirrhosis: Is There a Role for Hemostatic Factors?

Variceal bleeding is a frequent and ominous complication of liver cirrhosis. Fortunately, primary prophylaxis with ß blockers or esophageal band ligation effectively reduces the risk of variceal bleeding and its associated mortality. Periodic endoscopic surveillance of esophageal varices (EV) is currently recommended in every patient with cirrhosis for early detection of EV and initiation of primary variceal bleeding prophylaxis is indicated for high-risk patients. During the last decades several noninvasive tests have emerged, aiming to facilitate access, reduce cost, and avoid unnecessary risk associated with endoscopic EV surveillance. In addition, several hemostatic abnormalities have been described in cirrhosis, and their role in variceal bleeding pathogenesis is yet to be defined. In this article, we review and critically analyze the accuracy of noninvasive EV predictors and utility of hemostatic factors to predict individual variceal bleeding risk. In addition, we summarize available data regarding the therapeutic role of hemostatic factors in primary prevention of variceal bleeding and early recurrence after an initial episode of variceal hemorrhage.

Correlación de valores de TTPa con anti factor Xa para establecer rango terapéutico en tratamiento anticoagulante con heparina sódica / Correlation between aPTT and antifactor Xa to determine therapeutic ranges for unfractionated heparin

Background: The therapeutic range (TR) of activated partial thromboplastin time (aPTT) for unfractionated heparin (UFH) dosing was established in the 1970 decade. Since then aPTT determination has changed. Current TR may be sub or supra-therapeutic depending on the reagents of the test, and therefore, responsible for complications of therapy. Aim: To establish the TR for UFH dosing in our institution using antifactor Xa analysis as reference standard. Material and Methods: After obtaining an informed consent, 43 blood samples were obtained for aPTT determination and antifactor Xa assay in 23 patients treated with intravenous UFH. Samples were processed at Emergency and Hemostasis Labs. We excluded patients receiving other anticoagulants, with thrombophilia, pregnancy or liver disease. Results: Mean aPTT values in the Hemostasis and Emergency labs ​​were 57.1 ± 18.9 and 56.6 ± 18.3 seconds, respectively (p = 0.77). The squared correlation coefficients between aPTT and antifactor Xa at hemostasis and emergency labs were R2 0.5 and 0.45 respectively, p < 0.001. Using a linear regression analysis, therapeutic aPTT range values ​​in our laboratory were established between 50 and 80 seconds, corresponding to antifactor Xa values of 0.3 to 0.7 IU/mL. Conclusions: According to current recommendations, validation of aPTT determination with reference techniques should be done in every institution.