Revisão sistemática e meta-análise de estudos de diagnóstico e prognóstico: um tutorial

As revisões sistemáticas com meta-análise de estudos de exames diagnósticos ou de fatores prognósticos são ferramentas de pesquisa ainda em fase de desenvolvimento. O objetivo do presente texto é descrever a metodologia de revisão sistemática e de meta-análise deste tipo de estudos, passo a passo. Foi feita a revisão da literatura sobre o tema, compilando as recomendações e organizando o texto em: a) Introdução, b) Setalhamento dos oito passos a serem seguidos, c) Forma de publicação da revisão sistemática com meta-análise e d) Conclusão. Foram descritos os métodos de revisão sistemática de forma detalhada, com análise crítica dos métodos de compilação estatística dos resultados, com ênfase na utilização da curva Summary Receiver Operator Characteristic. Forneceu-se referência para os detalhes de cada técnica estatística utilizada na meta-análise. Concluímos que as revisões sistemáticas com meta-análise de exames diagnósticos ou de fatores prognósticos são valiosas na compilação de dados de vários estudos sobre o mesmo tema, reduzindo vieses e aumentando o poder estatístico da pesquisa primária.

Right Ventricular Doppler Echocardiographic Study of Indeterminate Form of Chagas Disease

Background: Patients with indeterminate form of Chagas disease/cardiac normality (ICD/CN) exhibited normal electrocardiograms and chest X-rays; however, more sophisticated tests detected some degree of morphological and functional changes in the heart. Objective: To assess the prevalence of systolic and diastolic dysfunction of the right ventricle (RV) in patients with ICD/CN. Methods: This was a case–control and prevalence study. Using Doppler two-dimensional echocardiography (2D), 92 patients were assessed and divided into two groups: group I (normal, n = 31) and group II (ICD/CN, n = 61). Results: The prevalence of RV systolic dysfunction in patients in groups I and II was as follows: fractional area change (0.0% versus 0.6%), mobility of the tricuspid annulus (0.0% versus 0.0%), and S-wave tissue Doppler (6.4% versus 26.0%, p = 0.016). The prevalence of global disorders such as the right myocardial performance index using tissue Doppler (16.1% versus 27.8%, p = 0.099) and pulsed Doppler (61.3% versus 68%, p = 0.141) and diastolic disorders such as abnormal relaxation (0.0% versus 6.0%), pseudonormal pattern (0.0% versus 0.0%), and restrictive pattern (0.0% versus 0.0%) was not statistically different between groups. Conclusion: The prevalence of RV systolic dysfunction was estimated to be 26% (S wave velocity compared with other variables), suggesting incipient changes in RV systolic function in the ICD/CN group.

Bounding right-arm rotation distances

Rotation distance quantifies the difference in shape between two rooted binary trees of the same size by counting the minimum number of elementary changes needed to transform one tree to the other. We describe several types of rotation distance, and provide upper bounds on distances between trees with a fixed number of nodes with respect to each type. These bounds are obtained by relating each restricted rotation distance to the word length of elements of Thompson's group F with respect to different generating sets, including both finite and infinite generating sets.

ParallelKnoppix tutorial

This note shows how to set up a Linux cluster for MPI parallel processing using ParallelKnoppix, a bootable CD.