International journal of epidemiology
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QT interval prolongation, a predictor of cardiac arrhythmias, and elevated heart rate are associated with higher risk of cardiovascular mortality. Observationally testosterone is associated with shorter corrected QT interval and slower heart rate; however, the evidence is open to residual confounding and reverse causality. We examined the association of testosterone with electrocardiogram (ECG) parameters using a separate-sample instrumental variable (SSIV) estimator. ⋯ Our findings do not corroborate observed protective associations of testosterone with QT interval or heart rate among men, but potentially suggest effects in the other direction. Replication in a larger sample is required.
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Associations between anthropometry and head and neck cancer (HNC) risk are inconsistent. We aimed to evaluate these associations while minimizing biases found in previous studies. ⋯ Waist circumference and waist-to-hip ratio were associated positively with HNC risk regardless of smoking status, whereas a positive association with BMI was only found in never smokers.
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Observational Study
No evidence that genetically reduced 25-hydroxyvitamin D is associated with increased risk of ischaemic heart disease or myocardial infarction: a Mendelian randomization study.
Low plasma 25-hydroxyvitamin D [p-25(OH)D] is associated with increased risk of ischaemic heart disease and with the subgroup myocardial infarction. However, whether this association is causal or due to confounding or reverse causation is presently unknown. We tested the hypothesis that genetically reduced plasma 25(OH)D is associated with increased risk of ischaemic heart disease and myocardial infarction. ⋯ We found no evidence to suggest that genetically reduced p-25(OH)D is associated with increased risk of ischaemic heart disease or myocardial infarction.
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To examine the incremental predictive value of genetic risk scores of coronary heart disease (CHD) in the 10-year risk prediction of incident CHD. ⋯ Although the genetic risk scores based on 152 SNPs were associated with incident CHD, they did not improve risk prediction. This discrepancy may be the result of SNP discovery for prevalent rather than incident CHD, since the SNPs do improve prediction for prevalent disease.
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Observational Study
Milk intake is not associated with ischaemic heart disease in observational or Mendelian randomization analyses in 98,529 Danish adults.
Observationally, reports on the association between milk intake and risk of ischaemic heart disease (IHD) and myocardial infarction (MI) have produced conflicting results; and no previous large-scale study using the lactase persistent/non-persistent LCT-13910 C/T genotype as a largely unconfounded proxy for milk intake free of reverse causation has been conducted. We tested the hypothesis that milk intake observationally and genetically through the LCT-13910 C/T genotype is associated with risk of IHD and MI in a Mendelian randomization design. ⋯ Milk intake was not associated with risk of IHD or MI, observationally or genetically.