HED 343 Cross-Sectional & Case-Control Studies

HED 343 Cross-Sectional & Case-Control Studies -...

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Cross-Sectional Studies prevalence studies, often conducted as surveys Use the individual human as the unit of analysis Relate exposure factors to disease or some other health outcome
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Important Features The prevalence of the disease or health outcome is used instead of incidence of the outcome relate exposure factors to health outcomes at the same point in time
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Example 1 100 elderly women were given a physical exam on October 1, 1998. During the exam serum cholesterol was measured and a diagnosis of coronary heart disease made, if present. Many people with heart disease may have been advised to lower their serum cholesterol by diet and drugs
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Notice A cross-sectional study would under- estimate the strength of the positive association between serum cholesterol and heart disease
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Example 2 Smoking usually declines after a heart attack. Thus, a cross-sectional study would underestimate the strength of the positive association between smoking and the subsequent outcome of heart disease Smoking might be negatively related to heart disease prevalence
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Major Problems with Cross- Sectional Studies 1) difficult to determine which factor is the cause and which factor is the effect 2) possibility that the disease has already influenced the level of the exposure factor
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Quality of the data Better than an ecologic study The validity of cross-sectional data can be questionable However, findings may be valid and of high quality. When the disease or outcome cannot influence the exposure factor, and when the exposure factor is not strongly related to survivorship
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Advantages Cheap Simple Quick to conduct.
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This note was uploaded on 04/12/2009 for the course HED 10520 taught by Professor Edmundson during the Spring '08 term at University of Texas.

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HED 343 Cross-Sectional & Case-Control Studies -...

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