104 research outputs found
A importância da evidência
Evidence-based Medicine (EBM) has become a major source of medical knowledge. It handles complexities of virtually every method or technique used in research. The knowledge on how the EBM researcher retrieves information, judges for relevance and analyzes derived data is invaluable for the skillful reader of medical scientific reports
BAYESIAN HYPOTHESIS TEST: Using Surface Integrals to Distribute Prior Information Among the Hypotheses
A solution to the problem of transferring the prior preferences about the paraIlleters of interest to the spaces defined by the hypotheses in test is proposed. We make use of surface (line) integrals to obtain tlus solution
Sequential Allocation to Balance Prognostic Factors in a Psychiatric Clinical Trial
OBJECTIVE: This paper aims to describe and discuss a minimization procedure specifically designed for a clinical trial that evaluates treatment efficacy for OCD patients. METHOD: Aitchison's compositional distance was used to calculate vectors for each possibility of allocation in a covariate adaptive method. Two different procedures were designed to allocate patients in small blocks or sequentially one-by-one. RESULTS: We present partial results of this allocation procedure as well as simulated data. In the clinical trial for which this procedure was developed, successful balancing between treatment arms was achieved. Separately, in an exploratory analysis, we found that if the arrival order of patients was altered, most patients were allocated to a different treatment arm than their original assignment. CONCLUSION: Our results show that the random arrival order of patients determine different assignments and therefore maintains the unpredictability of the allocation method. We conclude that our proposed procedure allows for the use of a large number of prognostic factors in a given allocation decision. Our method seems adequate for the design of the psychiatric trials used as models. Trial registrations are available at clinicaltrials.gov NCT00466609 and NCT00680602
Meta-Análise Caso a Caso Usando apenas Funções de Verossimilhança
Este trabalho tem o objetivo de ser uma pequena resenha da meta análise caso a caso, e a ênfase é dada a mistura de proporções. Comparamos três regiões onde são observados processos de Bernoulli em subáreas amostradas da região. Fazemos uso das verossimilhanças associadas a cada observação e mostramos que a mistura dessas verossimilhanças é mais informativa do que em considerar-se apenas uma observação da estatística suficiente para um único parâmetro. A motivação é fruto de um trabalho que realizamos com animais silvestres ao compararmos três áreas com respeito à “end-points” cito genéticos; Bueno et all (2000) e Pereira et all (2002). Embora utilizemos no presente trabalho os mesmos números daqueles artigos, mudamos o problema para comparar três regiões brasileiras quanto à frequência de obesos em alunos de escolas de segundo grau
Testing allele homogeneity: the problem of nested hypotheses
Background: The evaluation of associations between genotypes and diseases in a case-control framework plays an important role in genetic epidemiology. This paper focuses on the evaluation of the homogeneity of both genotypic and allelic frequencies. The traditional test that is used to check allelic homogeneity is known to be valid only under Hardy-Weinberg equilibrium, a property that may not hold in practice.
Results: We first describe the flaws of the traditional (chi-squared) tests for both allelic and genotypic homogeneity. Besides the known problem of the allelic procedure, we show that whenever these tests are used, an incoherence may arise: sometimes the genotypic homogeneity hypothesis is not rejected, but the allelic hypothesis is. As we argue, this is logically impossible. Some methods that were recently proposed implicitly rely on the idea that this does not happen. In an attempt to correct this incoherence, we describe an alternative frequentist approach that is appropriate even when Hardy-Weinberg equilibrium does not hold. It is then shown that the problem remains and is intrinsic of frequentist procedures. Finally, we introduce the Full Bayesian Significance Test to test both hypotheses and prove that the incoherence cannot happen with these new tests. To illustrate this, all five tests are applied to real and simulated datasets. Using the celebrated power analysis, we show that the Bayesian method is comparable to the frequentist one and has the advantage of being coherent.
Conclusions: Contrary to more traditional approaches, the Full Bayesian Significance Test for association studies provides a simple, coherent and powerful tool for detecting associations
Fatores influenciadores da intenção de doar sangue: proposição de um modelo exploratório
Purpose – Identify the main factors that significantly influence individuals living in the metropolitan region of Belo Horizonte / MG to donate blood.Design/methodology/approach – Methodologically, it was decided to develop a quantitative research, developed in the light of structural equation modeling, allowing the development of an exploratory behavioral model about the intention to donate blood.Findings – As main results, it was identified that the 'attitude towards screening' contributes significantly to the 'perception of safety' that the individual has about the process of blood donation.Research limitations/implications – Difficulty of access to the main hemotherapy center in the state, Minas Gerais Blood Bank Foundation (HEMOMINAS), a fact that prevented access to up-to-date data on the region's blood donation scenario.Practical implications – The indicators that are directly related to the practice of blood donation obtained statistically significant mean differences between the group of individuals who already donated blood and those who never donated, the former being more sensitive to calls for donation.Originality/value – There is a deepening of the knowledge of the variables that influence the individual who voluntarily performs an act such as blood donation. In this sense, this study provides inputs for the development of more assertive, efficient and effective blood donation public policies, contributing to the recovery of blood banks and raising the rate of donors in the country.Finalidade - Identificar os principais fatores que influenciam significativamente indivíduos residentes na Região Metropolitana de Belo Horizonte/MG a doarem sangueDesenho / metodologia / abordagem - Metodologicamente optou-se por desenvolver uma pesquisa quantitativa, desenvolvida à luz da modelagem de equações estruturais, permitindo que fosse desenvolvido um modelo exploratório comportamental acerca da intenção de doar sangue.Constatações - Como principais resultados identificou-se que a ‘atitude em relação à triagem’ contribui significativamente para a ‘percepção de segurança’ que o indivíduo possui acerca do processo de doação de sangue.Limitações / implicações da pesquisa - Dificuldade de acesso ao principal centro de hemoterapia do estado, a Fundação Centro de Hematologia e Hemoterapia do Estado de Minas Gerais (HEMOMINAS), fato que impediu o acesso a dados atualizados sobre o cenário de doação sanguínea da região.Implicações práticas - Os indicadores que estão diretamente relacionados à prática da doação sanguínea obtiveram diferenças de médias estatisticamente significantes entre o grupo de indivíduos que já doaram sangue e que aqueles que nunca doaram, sendo que os primeiros são mais sensíveis aos apelos em prol da doação.Originalidade / valor - Aprofundamento no conhecimento das variáveis que influenciam o indivíduo que, voluntariamente, executa um ato como a doação de sangue. Nesse sentido, este estudo fornece insumos para o desenvolvimento de políticas públicas de doação de sangue mais assertivas, eficazes e efetivas, contribuindo para a recuperação dos bancos de sangue e elevação da taxa de doadores do país
Stretching and Joint Mobilization Exercises Reduce Call-Center Operators’ Musculoskeletal Discomfort and Fatigue
AIM: We sought to evaluate musculoskeletal discomfort and mental and physical fatigue in the call-center workers of an airline company before and after a supervised exercise program compared with rest breaks during the work shift. INTRODUCTION: This was a longitudinal pilot study conducted in a flight-booking call-center for an airline in São Paulo, Brazil. Occupational health activities are recommended to decrease the negative effects of the call-center working conditions. In practice, exercise programs are commonly recommended for computer workers, but their effects have not been studied in call-center operators. METHODS: Sixty-four call-center operators participated in this study. Thirty-two subjects were placed into the experimental group and attended a 10-min daily exercise session for 2 months. Conversely, 32 participants were placed into the control group and took a 10-min daily rest break during the same period. Each subject was evaluated once a week by means of the Corlett-Bishop body map with a visual analog discomfort scale and the Chalder fatigue questionnaire. RESULTS: Musculoskeletal discomfort decreased in both groups, but the reduction was only statistically significant for the spine and buttocks (p=0.04) and the sum of the segments (p=0.01) in the experimental group. In addition, the experimental group showed significant differences in the level of mental fatigue, especially in questions related to memory Rienzo, #181ff and tiredness (p=0.001). CONCLUSIONS: Our preliminary results demonstrate that appropriately designed and supervised exercise programs may be more efficient than rest breaks in decreasing discomfort and fatigue levels in call-center operators
Meta-analysis of infrapopliteal angioplasty for chronic critical limb ischemia
BackgroundPercutaneous transluminal angioplasty has been used with increasing frequency in the treatment of infrainguinal arterial occlusive disease. This meta-analysis aimed to assess the middle-term outcomes after crural angioplasty in patients with chronic critical limb ischemia and compare results with a meta-analysis of popliteal-to-distal vein bypass graft.MethodsData were retrieved from 30 articles published from 1990 through 2006 (63% of articles published between 2000 and 2006). All studies used survival analysis, reported a 12-month cumulative rate of patency or limb salvage, and included at least 15 infrapopliteal angioplasties. The outcome measures were immediate technical success, primary and secondary patency, limb salvage, and patient survival. Data from life-tables, survival curves, and texts were used.ResultsThe pooled estimate of success was 89.0% ± 2.2% for immediate technical result. Results at 1 and 36 months were 77.4% ± 4.1% and 48.6% ± 8.0% for primary patency, 83.3% ± 1.4% and 62.9% ± 11.0% for secondary patency, 93.4% ± 2.3% and 82.4% ± 3.4% for limb salvage, and 98.3% ± 0.7% and 68.4% ± 5.5% for patient survival, respectively. Studies with >75% of the limbs with tissue loss fared worse than their respective comparative subgroup for technical success and patency but not for limb salvage or survival. No publication bias was detected.ConclusionThe technical success and subsequent durability of crural angioplasty are limited compared with bypass surgery, but the clinical benefit is acceptable because limb salvage rates are equivalent to bypass surgery. Further studies are necessary to determine the proper role of infrapopliteal angioplasty
Dentist Behavior Concerning Occupational Biological Accidents.
Objetivo: revisar as condutas a serem adotadas em casos de acidente com material biológico contaminado, propondo um fluxograma de encaminhamento aos setores de competência, além de pesquisar junto aos profissionais de Odontologia o conhecimento dos mesmos a respeito das condutas frente aos referidos acidentes. Outro objetivo foi avaliar os aspectos éticos e legais envolvidos com a questão. Material e métodos: a pesquisa foi realizada por meio do envio de questionários distribuídos de forma aleatória à cirurgiões dentistas da cidade de Macaé-RJ. Posteriormente os dados foram tabulados e analisados por estatística simples. Resultados: dentre os pesquisados, 95,2% disseram conhecer os riscos biológicos presentes na atividade clínica diária e 38,1% responderam que já sofreram algum tipo de acidente biológico, sendo que metade dos participantes declararam conhecer as condutas a serem tomadas nessas situações. Conclusões: foi possível propor um fluxograma de fácil entendimento para os interessados. Há um conhecimento incipiente dos profissionais questionados sobre o protocolo a ser seguido em caso de acidente com contaminação biológica, bem como a inobservância de importantes aspectos éticos e legais que norteiam a profissão. Aim: review the measures to be adopted in cases of accidents with biological material contaminated by proposing a flow chart for referral to the areas of jurisdiction, and research from the professionals of Dentistry of the same knowledge about the behavior front to such accidents, as well as the ethical and legal issues involved with the issue. Material and methods: the study was conducted by sending questionnaires distributed randomly to dentists in the city of Macaé. Subsequently, data were tabulated and analyzed by simple statistics. Results: among those surveyed, 95.2% said they were aware of biological hazards present in daily practice and 38.1% said they had experienced some kind of biological accident, half of the participants said they knew the conduct to be taken in these situations. Conclusions: it was possible to propose a flow chart easy to understand for those interested. There is an incipient knowledge of the professionals were asked about the protocol to be followed in case of accidents with biological contamination and the failure of important ethical and legal issues that guide the profession
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