Question

4. A study was performed with 100 patients at a hospital newly diagnosed with oropharyngeal cancer and 200 controls from the same hospital with other benign conditions. Swabs from the oropharynx (throat) were collected from cases after diagnosis and controls after enrollment in the study, and examined for the presence of Human Papilloma Virus (HPV). The purpose of this study was to evaluate the association between HPV infection and oropharyngeal cancer (D'Souza et al, 2007). Of those 100 cases with oropharyngeal cancer, 32 were positive for HPV. Of the 200 controls without oropharyngeal cancer, 8 were positive for HPV. 4.A. (4 pts) Construct a 2 x 2 table for this data. B) (4 pts) What are the odds of HPV detection (exposure) among the disease (those with cancer) and the nondiseased (those without cancer)? 4.C. (4 pts) Calculate the odds ratio and interpret the number you calculate.

Answer 1

Solution: There is two sample carried out from two different domain for experiment.

100 patients at a hospital newly diagnosed with orophrayngeal cancer. Similarly, 200 control from the same hospital with other benign condition (not having orophraygeal cancer)and examined for the presence of Human Papilloma Virus(HPV). The Purpose of this study was to evaluate the association between HPV infection and orophrayngeal cancer.

Of those 100 cases with oropharygeal cancer , 32 were positive for HPV and Of the 200 controls without oropharygeal cancer, 8 were positive for HPV

construction of 2X2 matrix of the data

	HPV(+ve)	HPV(-ve)	Total
disease(with cancer)	32	68	100
non disease(those without cancer)	8	192	200
Total	40	260

odds of success is the ratio of the probability of success or failure the outcome occurring in the presence and absence of that exposure.

So, odds of HPV detection(exposure) among the disease(those with cancer) and nondiseased(those without cancer) is given by

   $odds_s=\frac{\frac{32}{40}}{\frac{8}{40}}$

$odds_s=4$

This is odds of HPV +ve

An odds ratio (OR) is a measure of association between an exposure and an outcome. The OR represents the odds that an outcome will occur given a particular exposure, compared to the odds of the outcome occurring in the absence of that exposure.

odd of failure is given by

$odds_f=\frac{\frac{68}{260}}{\frac{192}{260}}$

$odds_f=0.35$

odd ratio is given by

$odds \ ratio=\frac{odds_s}{odds_f}$

. $odds \ ratio=\frac{4}{0.35}$

odds ratio is greater than 1 which menas there is strong association between HPV infection and orthopharyngeal cancer .