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28 Sep 2019
CASE ONE
The study is conducted to investigate the association betweenchewing tobacco and oral leukoplakia (a precancerous lesion) amongcurrently active professional baseball players in the southeasternUnited States. A roster of all active players is obtained (n=500).All potential study subjects agree to participate. Each subject hasan interview regarding current use of chewing tobacco and has hismouth examined by a dentist. Of the 500 subjects, 125 subjects chewtobacco and 375 do not chew tobacco. Of the chewers, 25 haveevidence of oral leukoplakia. Of the non-chewers, 15 have evidenceof oral leukoplakia. All 500 players were followed for a period of5 years. Of those who had evidence of oral leukoplakia, 18 died ofsome type of oral cancer.
- Draw a 2 x 2 table demonstrating the relationship betweenchewing tobacco and oral leukoplakia. In drawing this table, putthe exposure variable on the columns and the health outcomevariable on the rows.
- Draw a second 2 x 2 table demonstrating the relationshipbetween chewing tobacco and oral leukoplakia, but this time, putthe exposure variable on the rows and the health outcome variableon the columns.
- Using the table drawn in part a, compute the prevalence ratioand the prevalence odds ratio of oral leukoplakia for chewerscompared to non-chewers. Are these two estimates close toone-another? Why are these prevalence measures and not incidencemeasures?
- Using the table drawn in part b, compute the prevalence ratioand the prevalence odds ratio of oral leukoplakia for chewerscompared to non-chewers. Are these estimates equal to theircorresponding estimates computed using the table drawn in part a?Explain.
- Ignoring the issue of statistical inference and the control ofother variables, what do these results say about the relationshipbetween chewing tobacco and the presence of oral leukoplakia?
- Calculate the case-fatality rate (actually, a risk) in thisstudy. Why is this a measure of risk?
- Based on the information provided, why canât you evaluatewhether tobacco chewers have a higher case-fatality risk thannon-chewers?
CASE ONE
The study is conducted to investigate the association betweenchewing tobacco and oral leukoplakia (a precancerous lesion) amongcurrently active professional baseball players in the southeasternUnited States. A roster of all active players is obtained (n=500).All potential study subjects agree to participate. Each subject hasan interview regarding current use of chewing tobacco and has hismouth examined by a dentist. Of the 500 subjects, 125 subjects chewtobacco and 375 do not chew tobacco. Of the chewers, 25 haveevidence of oral leukoplakia. Of the non-chewers, 15 have evidenceof oral leukoplakia. All 500 players were followed for a period of5 years. Of those who had evidence of oral leukoplakia, 18 died ofsome type of oral cancer.
- Draw a 2 x 2 table demonstrating the relationship betweenchewing tobacco and oral leukoplakia. In drawing this table, putthe exposure variable on the columns and the health outcomevariable on the rows.
- Draw a second 2 x 2 table demonstrating the relationshipbetween chewing tobacco and oral leukoplakia, but this time, putthe exposure variable on the rows and the health outcome variableon the columns.
- Using the table drawn in part a, compute the prevalence ratioand the prevalence odds ratio of oral leukoplakia for chewerscompared to non-chewers. Are these two estimates close toone-another? Why are these prevalence measures and not incidencemeasures?
- Using the table drawn in part b, compute the prevalence ratioand the prevalence odds ratio of oral leukoplakia for chewerscompared to non-chewers. Are these estimates equal to theircorresponding estimates computed using the table drawn in part a?Explain.
- Ignoring the issue of statistical inference and the control ofother variables, what do these results say about the relationshipbetween chewing tobacco and the presence of oral leukoplakia?
- Calculate the case-fatality rate (actually, a risk) in thisstudy. Why is this a measure of risk?
- Based on the information provided, why canât you evaluatewhether tobacco chewers have a higher case-fatality risk thannon-chewers?
Beverley SmithLv2
28 Sep 2019
