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

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

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

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

Chromosomal Damage and Apoptosis in Exfoliated Buccal Cells from Individuals with Oral Cancer

This study aimed to investigate cytological abnormalities indicative of chromosome damage (micronuclei) and apoptosis (karyorrhexis, pyknosis, and condensed chromatin) in exfoliated cells from the buccal mucosa of patients with oral cancer and control subjects. The sample included twenty individuals with oral cancer and forty individuals with normal buccal mucosa. Material was collected from the cheek epithelium in areas with lesions and areas without abnormalities. A minimum of one thousand cells was analyzed. Micronuclei were found significantly more frequently in cells collected from lesions than in cells from normal areas, independent of the presence/absence of cancer (P < 0.0001). They were also significantly more frequent in smokers and in mouthwash users (P < 0.0001). Apoptosis occurred significantly less frequently in individuals with oral cancer (P < 0.0001). These results show that oral cancer is associated with higher frequency of chromosomal damage and suggest that apoptosis is compromised in the buccal cells of individuals with this kind of neoplasia

Prevalence of low back pain in the elderly population: a systematic review

The aim of this study was to estimate the prevalence of low-back pain (LBP) and to identify the level of functional disability in elderly individuals in different populations. From January 1985 to October 2018, a search was performed using the following databases: Embase, LILACS, SciELO, Scopus, Medline, and the Web of Science. The descriptors were low-back pain, back pain, lower-back pain, prevalence, and elderly in Portuguese and English. Two independent reviewers conducted a search for studies and evaluated their methodological quality. The search strategy returned 2186 titles, and 35 were included in this review. The studies evaluated 135,059 elderly individuals aged between 60 and 102 years, and the prevalence of LBP ranged from 21% to 75%. The levels of functional disability, as well as functional difficulties, activities of daily living, and physical capacity, were identified in 60% of the studies. This review indicated a high prevalence of LBP in elderly individuals and functional disability that affects factors important for independence. However, the studies used different methodologies, suggesting that more studies be conducted with scientific accuracy, methodological quality, and low risk of bias to contribute to the proposal of preventive actions for elderly populations