Journal of clinical epidemiology
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In the epidemiologic literature, one finds three criteria for confounding, which we will call the classical (marginal), operational (change-in-estimate) and conditional criteria. We define mavericks to be covariates that satisfy the operational criterion, but not the classical criterion. We present what is known about the problems of mavericks for estimating odds ratios and clarify the interpretation of odds ratios. Key results are: (1) omitting mavericks biases odds ratios towards 1; (2) omitting mavericks cannot artificially introduce an effect in contrast to omitting classical confounders; (3) the operational criterion for confounding corresponds to the conditional criterion when estimating odds ratios, but for relative risks, there are no mavericks (i.e. the classical and operational criterion correspond); and (4) the interpretation of odds ratios obtained from standard methods is that of comparing proportions, not of individual risk.
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The known risk factors of atherosclerotic diseases may be involved in the development of a subarachnoid hemorrhage. We studied the morbidity and mortality due to subarachnoid hemorrhage among 42,862 men and women aged 20-69 years who had participated in a large health survey in Finland. During a mean follow-up of 12 years, 102 non-fatal and 85 fatal cases of subarachnoid hemorrhage were observed. ⋯ The age-adjusted relative risks of subarachnoid hemorrhage for lean, hypertensive smokers were 18.3 (95% confidence interval (CI), 7.8-42.7) among women and 6.7 (95% CI, 2.3-19.7) among men as compared to the risk among subjects without these risk factors. We conclude that modifiable risk factors are predictive of subarachnoid hemorrhage, for which reason subarachnoid hemorrhage may in part be preventable. Leanness combined with arterial hypertension and/or smoking, in particular, poses a substantially elevated risk.
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Comparative Study
Pharmacoepidemiology in pre-approval clinical trial safety monitoring.
Applications of pharmacoepidemiology to the pre-approval safety monitoring of investigational drugs are examined and compared with the post-approval applications. Pre-approval epidemiologic assessments of drug safety can complement clinical assessments of rare, serious adverse events occurring in open label uncontrolled clinical trials. ⋯ Advance planning of historical data sources is essential as is an effective clinical trial data management system. Implications for methodologic research and for drug development are discussed.
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We present the first prevalence study of specific headache entities using the operational diagnostic criteria of the International Headache Society. One thousand 25-64 year old men and women, who lived in the western part of Copenhagen County were randomly drawn from the Danish National Central Person Registry. All subjects were invited to a general health examination focusing on headache and including: a self-administered questionnaire concerning sociodemographic variables, a structured headache interview and a general physical and neurological examination. ⋯ Differences according to sex were significant with a male: female ratio of 1:3 in migraine, and 4:5 in tension-type headache. The prevalence of tension-type headache decreased with increasing age, whereas migraine showed no correlation to age within the studied age interval. Headache disorders are extremely prevalent and represent a major health problem, which merits increased attention.
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Risk of cardiovascular events was determined over 24 years of surveillance in relation to general adiposity reflected by relative weight and by regional obesity estimated by skinfolds and waist girth per inch of height. Upper quintile values of relative weight, subscapular skinfolds and waist girth were each associated with increased risks of cardiovascular disease in both sexes. Risk of total cardiovascular events increased with the degree of regional, central or abdominal obesity. ⋯ In women, only the subscapular-to-triceps skinfold ratio independently contributes to CHD, cardiovascular and all cause mortality. Regional obesity appears to be an independent contributor to cardiovascular disease at a given level of general adiposity, its effect only partially mediated through promotion of other known risk factors. These data suggest that cardiovascular disease is as closely linked to abdominal as to general adiposity.