International journal of epidemiology
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Mendelian randomization uses a carefully selected gene as an instrumental-variable (IV) to test or estimate an association between a phenotype and a disease. Classical IV analysis assumes linear relationships between the variables, but disease status is often binary and modelled by a logistic regression. When the linearity assumption between the variables does not hold the IV estimates will be biased. The extent of this bias in the phenotype-disease log odds ratio of a Mendelian randomization study is investigated. ⋯ In a Mendelian randomization study with a binary disease outcome the bias associated with estimating the phenotype-disease log odds ratio may be of practical importance and so estimates should be subject to a sensitivity analysis against different amounts of hypothesized confounding.
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The association between extremes of relative body weight and mortality has not been well characterized in developing countries. A prospective cohort study was conducted in Mumbai (India) to study the association of relative body weight, as estimated by body mass index [BMI = weight (kg)/height(2) (m(2))], with mortality. ⋯ In Mumbai, under-weight was associated with an increased risk of pre-mature death. Despite the growing concerns regarding the gradual transition toward increasing rates of obesity, under-nutrition remains a major health problem in India. This study suggests the need for public health policies focusing on reducing under-nutrition.
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UK Biobank is a large prospective study in the UK to investigate the role of genetic factors, environmental exposures and lifestyle in the causes of major diseases of late and middle age. Extensive data and biological samples are being collected from 500,000 participants aged between 40 and 69 years. The biological samples that are collected and how they are processed and stored will have a major impact on the future scientific usefulness of the UK Biobank resource. ⋯ The sample handling and storage protocol adopted by UK Biobank provides quality assured and validated methods that are feasible within the available funding and reflect the size and aims of the project. Experience from recruiting and processing the first 40,000 participants to the study demonstrates that the adopted methods and technologies are fit-for-purpose and robust.
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Review Meta Analysis
Low serum vitamin D levels and tuberculosis: a systematic review and meta-analysis.
To explore the association between low serum vitamin D and risk of active tuberculosis in humans. ⋯ Low serum vitamin D levels are associated with higher risk of active tuberculosis. Although more prospectively designed studies are needed to firmly establish the direction of this association, it is more likely that low body vitamin D levels increase the risk of active tuberculosis. In view of this, the potential role of vitamin D supplementation in people with tuberculosis and hypovitaminosis D-associated conditions like chronic kidney disease should be evaluated.