Estudos epidemiológicos na avaliação de efetividade do Programa de Controle da Doença de Chagas: discussão metodológica Epidemiological studies for evaluating the effectiveness of the Chagas' Disease Control Program: a discussion on methods

Este artigo tem como objetivo apresentar e discutir os aspectos metodológicos de diferentes delineamentos epidemiológicos que foram testados como modelos para avaliação de efetividade das ações do programa de controle da doença de Chagas (PCDCh), na redução da incidência da infecção pelo Trypanosama cruzi (agente etiológico) naqueles nascidos após a intervenção, em diferentes fases do programa. O PCDCh empregou como intervenção desde sua fase inicial a utilização de inseticidas no controle do vetor domiciliado, o Triatoma infestans (triatomíneo). Os delineamentos utilizados foram: 1) Estudo quase-experimental conduzido na fase de implantação do PCDCh, quando áreas para comparação eram disponíveis. Foram comparadas áreas com intervenção (10 e 5 anos) a área sem intervenção. A efetividade do PCDCh foi avaliada comparando as taxas de infecção pelo T. cruzi estimadas no estudo com aquelas obtidas anteriormente no inquérito sorológico nacional (informação basal), realizado no Brasil entre 1975-1980; 2) Estudo de painel conduzido em uma área com 13 anos de intervenção. Os objetivos foram o de avaliar a efetividade do PCDCh e verificar se a duração do programa é um fator determinante para induzir mudanças nas taxas de incidência. As taxas de infecção pelo T.cruzi estimadas na investigação foram comparadas às taxas obtidas anteriormente no inquérito sorológico nacional (1975-1980) e com aquelas obtidas no estudo quase-experimental (1987), ocasião em que a área encontrava-se há 5 anos sob intervenção; 3) Estudo caso-controle com objetivo de identificar fatores de risco associados à infecção pelo T. cruzi foi incorporado ao inquérito sorológico que estava sendo realizado para avaliar as ações do PCDCh em áreas em vigilância epidemiológica. Os modelos testados em diferentes fases do PCDCh mostraram-se adequados para avaliar sua efetividade: as metodologias podem ser estendidas a outros programas; são éticos, pois são implementados durante a execução dos programas; permitem inferência de relação causa-efeito; são viáveis do ponto de vista operacional, podendo ser incluídos na fase de planejamento de programas de saúde.<br>The present paper describes the methodological aspects of different epidemiological designs tested as a model to evaluate the effectiveness of the Chagas' disease control program. The main outcome was the reduction of infection rates by Trypanosam cruzi (etiological agent) measured by serology, in those born after the intervention. The actions of Chagas' disease control programs were based on house spraying with insecticide with the objective of controlling the vector Triatoma infestans (intermediate hosts of T. cruzi). The epidemiological designs used were: 1) Quasi-experimental, conducted in 1987, when an area for comparison was available. The reduction of T. cruzi infection rates in the area where intervention had been carried out for 5 and 10 years was compared with those where there was no intervention (control). The program effectiveness was estimated by comparing the infection rates found in the study with those published by the Chagas' disease serological survey (1975-1980); 2) Panel study, conducted in one area with 13 years of intervention. The objectives were to investigate the T. cruzi infection transmission pattern in a cohort born after the intervention and to verify whether the duration of the program was a determinant factor in inducing change in the incidence. The reduction of T. cruzi infection rates was estimated from data collected on three separate occasions: a national serological survey (1975-80), a quasi-experimental study (1987) and the present investigation (1995); 3) Nested case-control, to evaluate the risk factors of T.cruzi infection, incorporated within a serological survey of school children, which was implemented by the National Health Foundation to evaluate the effectiveness of the Chagas' disease control program. The models tested in different phases of the Chagas' disease control program were adequate for evaluating the effectiveness of the program; methodologies can be extended to other programs; they provide quick answers to the question formulated; they are ethical, since they can be carried out while programs are in progress; they are operationally feasible and might be included by public health institutions at the planning phase of programs

Global, regional, and national age-sex specific all-cause and cause-specific mortality for 240 causes of death, 1990-2013: a systematic analysis for the Global Burden of Disease Study 2013

Background Up-to-date evidence on levels and trends for age-sex-specific all-cause and cause-specific mortality is essential for the formation of global, regional, and national health policies. In the Global Burden of Disease Study 2013 (GBD 2013) we estimated yearly deaths for 188 countries between 1990, and 2013. We used the results to assess whether there is epidemiological convergence across countries. Methods We estimated age-sex-specific all-cause mortality using the GBD 2010 methods with some refinements to improve accuracy applied to an updated database of vital registration, survey, and census data. We generally estimated cause of death as in the GBD 2010. Key improvements included the addition of more recent vital registration data for 72 countries, an updated verbal autopsy literature review, two new and detailed data systems for China, and more detail for Mexico, UK, Turkey, and Russia. We improved statistical models for garbage code redistribution. We used six different modelling strategies across the 240 causes; cause of death ensemble modelling (CODEm) was the dominant strategy for causes with sufficient information. Trends for Alzheimer's disease and other dementias were informed by meta-regression of prevalence studies. For pathogen-specific causes of diarrhoea and lower respiratory infections we used a counterfactual approach. We computed two measures of convergence (inequality) across countries: the average relative difference across all pairs of countries (Gini coefficient) and the average absolute difference across countries. To summarise broad findings, we used multiple decrement life-tables to decompose probabilities of death from birth to exact age 15 years, from exact age 15 years to exact age 50 years, and from exact age 50 years to exact age 75 years, and life expectancy at birth into major causes. For all quantities reported, we computed 95% uncertainty intervals (UIs). We constrained cause-specific fractions within each age-sex-country-year group to sum to all-cause mortality based on draws from the uncertainty distributions. Findings Global life expectancy for both sexes increased from 65·3 years (UI 65·0–65·6) in 1990, to 71·5 years (UI 71·0–71·9) in 2013, while the number of deaths increased from 47·5 million (UI 46·8–48·2) to 54·9 million (UI 53·6–56·3) over the same interval. Global progress masked variation by age and sex: for children, average absolute differences between countries decreased but relative differences increased. For women aged 25–39 years and older than 75 years and for men aged 20–49 years and 65 years and older, both absolute and relative differences increased. Decomposition of global and regional life expectancy showed the prominent role of reductions in age-standardised death rates for cardiovascular diseases and cancers in high-income regions, and reductions in child deaths from diarrhoea, lower respiratory infections, and neonatal causes in low-income regions. HIV/AIDS reduced life expectancy in southern sub-Saharan Africa. For most communicable causes of death both numbers of deaths and age-standardised death rates fell whereas for most non-communicable causes, demographic shifts have increased numbers of deaths but decreased age-standardised death rates. Global deaths from injury increased by 10·7%, from 4·3 million deaths in 1990 to 4·8 million in 2013; but age-standardised rates declined over the same period by 21%. For some causes of more than 100 000 deaths per year in 2013, age-standardised death rates increased between 1990 and 2013, including HIV/AIDS, pancreatic cancer, atrial fibrillation and flutter, drug use disorders, diabetes, chronic kidney disease, and sickle-cell anaemias. Diarrhoeal diseases, lower respiratory infections, neonatal causes, and malaria are still in the top five causes of death in children younger than 5 years. The most important pathogens are rotavirus for diarrhoea and pneumococcus for lower respiratory infections. Country-specific probabilities of death over three phases of life were substantially varied between and within regions. Interpretation For most countries, the general pattern of reductions in age-sex specific mortality has been associated with a progressive shift towards a larger share of the remaining deaths caused by non-communicable disease and injuries. Assessing epidemiological convergence across countries depends on whether an absolute or relative measure of inequality is used. Nevertheless, age-standardised death rates for seven substantial causes are increasing, suggesting the potential for reversals in some countries. Important gaps exist in the empirical data for cause of death estimates for some countries; for example, no national data for India are available for the past decade