Performance and reference intervals of thrombin generation test: results from the Brazilian longitudinal study of adult health (ELSA-Brasil). A cross-sectional study

ABSTRACT BACKGROUND: The thrombin generation test (TGT) has shown promise for investigation of hemorrhagic and thrombotic diseases. However, despite its potential, it still needs standardization. Moreover, few studies have established reference values for TGT parameters. In Brazil, these values have not yet been established. OBJECTIVE: To determine TGT performance and reference intervals for TGT parameters in healthy individuals. DESIGN AND SETTING: Cross-sectional study conducted among participants in the Brazilian Longitudinal Study of Adult Health (Estudo Longitudinal de Saúde do Adulto, ELSA-Brasil). METHODS: The reference sample consisted of 620 healthy individuals. The calibrated automated thrombogram (CAT) method, under low and high tissue factor (TF) conditions, was used to assess thrombin generation. Test performance was analyzed using intra and interassay coefficients of variation (CV) and reference intervals were calculated using the nonparametric method proposed by the International Federation of Clinical Chemistry and the Clinical and Laboratory Standards Institute. RESULTS: The intraassay CV ranged from 1.4% to 2.2% and the interassay CV, 6.8% to 14.7%. The reference intervals for TGT parameters under low and high TF conditions were, respectively: lagtime: 3.0-10.3 and 1.4-3.7 min; endogenous thrombin potential (ETP): 1134.6-2517.9 and 1413.6-2658.0 nM.min; normalized ETP: 0.6-1.3 and 0.7-1.4; peak: 103.2-397.7 and 256.4-479.0 nM; normalized peak: 0.3-1.3 and 0.7-1.2; and time-to-peak: 5.6-16.0 and 3.4-6.7 min. These parameters were categorized relative to sex. Conclusion: TGT performance was adequate and the proposed reference intervals were similar to those of other studies. Our findings may be useful for consolidating the TGT, through contributing to its standardization and validation.

Associação entre a presença de anemia ferropriva com variáveis socioeconômicas e rendimento escolar / Association between the occurence of iron-deficiency anemia with socioeconomic variables and school performance

Modelo do estudo: Observacional transversal. Objetivo: Avaliar a associação entre a presença de anemia ferropriva com variáveis socioeconômicas e rendimento escolar. Método: Foram incluídas no estudo 124 crianças com idade entre seis e oito anos, estudantes do ensino fundamental de escolas municipais, as quais foram divididas em dois grupos de acordo com a presença (n=32) ou ausência de anemia (n=92). Os níveis de hemoglobina e ferro sérico foram determinados por método colorimétrico, a contagem de hemácias foi realizada utilizando a câmara de Neubauer, o hematócrito foi avaliado utilizando centrífuga de microhematócrito, e foram calculados os índices hematimétricos volume corpuscular médio, hemoglobina corpuscular média e concentração de hemoglobina corpuscular média. O desempenho escolar das crianças foi fornecido pelas escolas participantes e as variáveis socioeconômicas foram obtidas através de preenchimento de ficha clínica e do questionário socioeconômico da Associação Brasileira das Empresas de Pesquisa pelos pais ou responsáveis. Resultados: A prevalência de anemia ferropriva nos escolares foi de 25,8% que é considerada pelos parâmetros da OMS uma prevalência moderada. Foi observada uma maior proporção de crianças sem anemia que apresentaram melhores conceitos escolares e que pertencem aos níveis socioeconômicos mais altos do que de crianças com anemia. Contudo, não foram observadas diferenças estatisticamente significativas entre os grupos com relação ao rendimento escolar e as variáveis socioeconômicas. Conclusão: Uma prevalência moderada de anemia ferropriva foi encontrada nas crianças com idade entre seis e oitos anos, entretanto, não foi observada uma associação significativa entre a anemia ferropriva com variáveis socioeconômicas e o rendimento escolar. (AU)

Study design: Cross-sectional observational. Objective: Evaluate the association between the occurence of iron-deficiency anemia with socioeconomic variables and school performance. Method: They were included in the study 124 children aged between six and eight years old, municipal elementary school students, which were divided in two groups according to the presence (n=32) or absence of anemia (n=92). Hemoglobin and serum iron levels were determined by colorimetric method, red blood cells count was performed using Neubauer chamber, hematocrit was evaluated using microhematocrit centrifuge, and mean corpuscular volume, mean corpuscular hemoglobin, and mean corpuscular hemoglobin concentration hematimetric indexes were calculated. The school performance of children was provided by participating schools and socioeconomic variables were obtained by filling out the clinic file and the socioeconomic questionnaire of Brazilian Association of Research Companies by parents or guardians. Results: The prevalence of iron-deficiency anemia in school children was 25.8%, which is considered to be moderate. The proportion of better school grades was higher in children without anemia and in those belonging to the upper socioeconomic levels. However, it was not observed statistically differences between groups regarding school performance and socioeconomic variables. Conclusion: A moderate prevalence of iron-deficiency anemia was found in children aged between six and eight years old, however, it was not observed a significant association between irondeficiency anemia with socioeconomic variables and school performance. (AU)