Variability in baseline laboratory measurements of the Brazilian Longitudinal Study of Adult Health (ELSA-Brasil)

Multi-center epidemiological studies must ascertain that their measurements are accurate and reliable. For laboratory measurements, reliability can be assessed through investigation of reproducibility of measurements in the same individual. In this paper, we present results from the quality control analysis of the baseline laboratory measurements from the ELSA-Brasil study. The study enrolled 15,105 civil servants at 6 research centers in 3 regions of Brazil between 2008–2010, with multiple biochemical analytes being measured at a central laboratory. Quality control was ascertained through standard laboratory evaluation of intra- and inter-assay variability and test-retest analysis in a subset of randomly chosen participants. An additional sample of urine or blood was collected from these participants, and these samples were handled in the same manner as the original ones, locally and at the central laboratory. Reliability was assessed with the intraclass correlation coefficient (ICC), estimated through a random effects model. Coefficients of variation (CV) and Bland-Altman plots were additionally used to assess measurement variability. Laboratory intra and inter-assay CVs varied from 0.86% to 7.77%. From test-retest analyses, the ICCs were high for the majority of the analytes. Notably lower ICCs were observed for serum sodium (ICC=0.50; 95%CI=0.31–0.65) and serum potassium (ICC=0.73; 95%CI=0.60–0.83), due to the small biological range of these analytes. The CVs ranged from 1 to 14%. The Bland-Altman plots confirmed these results. The quality control analyses showed that the collection, processing and measurement protocols utilized in the ELSA-Brasil produced reliable biochemical measurements.

Glutamic acid decarboxylase antibodies are indicators of the course, but not of the onset, of diabetes in middle-aged adults: the Atherosclerosis Risk in Communities Study

To efficiently examine the association of glutamic acid decarboxylase antibody (GADA) positivity with the onset and progression of diabetes in middle-aged adults, we performed a case-cohort study representing the ~9-year experience of 10,275 Atherosclerosis Risk in Communities Study participants, initially aged 45-64 years. Antibodies to glutamic acid decarboxylase (GAD65) were measured by radioimmunoassay in 580 incident diabetes cases and 544 non-cases. The overall weighted prevalence of GADA positivity (³1 U/mL) was 7.3 percent. Baseline risk factors, with the exception of smoking and interleukin-6 (P ú 0.02), were generally similar between GADA-positive and -negative individuals. GADA positivity did not predict incident diabetes in multiply adjusted (HR = 1.04; 95 percentCI = 0.55, 1.96) proportional hazard analyses. However, a small non-significant adjusted risk (HR = 1.29; 95 percentCI = 0.58, 2.88) was seen for those in the highest tertile (³2.38 U/mL) of positivity. GADA-positive and GADA-negative non-diabetic individuals had similar risk profiles for diabetes, with central obesity and elevated inflammation markers, aside from glucose, being the main predictors. Among diabetes cases at study's end, progression to insulin treatment increased monotonically as a function of baseline GADA level. Overall, being GADA positive increased risk of progression to insulin use almost 10 times (HR = 9.9; 95 percentCI = 3.4, 28.5). In conclusion, in initially non-diabetic middle-aged adults, GADA positivity did not increase diabetes risk, and the overall baseline profile of risk factors was similar for positive and negative individuals. Among middle-aged adults, with the possible exception of those with the highest GADA levels, autoimmune pathophysiology reflected by GADA may become clinically relevant only after diabetes onset.

Medicina embasada em evidências / Evidence-based medicina

O aumento crescente das opções diagnósticas e terapêuticas cria a necessidade de avaliar sua efetividade, o que pode ser feito, por exemplo, com o ensaio clínico randomizado. A difusão deste e de outros métodos da epidemiologia clínica na prática médica propicia o paradigma da "medicina embasada em evidências". Ao enfatizar a necessidade de evidências clínico-epidemiológicas sólidas para as decisões clínicas, a medicina embasada em evidências forma a estrutura para a integração dos resultados de pesquisa na prática clínica. A evidência é graduada pelo delineamento de pesquisa, fornecendo normas que estabelecem qual o grau adequado para a tomada de decisão médica. A combinação desse novo paradigma com o poder das telecomunicações modernas está causando uma revolução no modo em que a medicina é praticada. O processo é facilitado pelo acesso dos clínicos às revisões quantitativas e aos guidelines (posicionamentos clínicos) delas derivados. As limitações das fontes tradicionais de evidências médicas e as vantagens das novas fontes de evidências, como o ACP Journal Club e a Cochrane Collaboration, são descritas. É importante que o médico se familiarize com os conceitos e técnicas do paradigma de medicina embasada em evidências.

Altos coeficientes de mortalidade em populaçoes adultas brasileiras--uma comparação internacional / High mortality rates among Brazilian adult populations--an international comparison

Adult disease in an increasingly important public health problem in Brazil. In order to compare adult mortality in Brazil to that in other countries, age-adjusted coefficients for adults aged 30-69 of the States of São Paulo and Rio Grande do Sul and of the city of Fortaleza (Ceará State) are compared to those of similarly aged adults in a series of 33, principally European, countries. The Brazilian population coefficients for overall, cerebrovascular and cardiovascular mortality are among the highest of the series; those for ischemic heart disease occupy median positions. These comparisons illustrate the precarious state of adult health in Brazil and, given the growing possibilities of preventing cardiovascular and other non-communicable diseases, help demonstrate the need for preventive programs in Brazil aimed at the major common and lethal diseases of the productive years of life.