Sample Case Control Essay

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2. Methods:
Study: To determine the effects of particular antibiotics on C. difficile infection, we will use a case-control study, which is the most appropriate design because we will begin by looking at those who have the CDI (health outcome) and determine from there which antibiotics (exposure) lead to the highest risk of infection. Furthermore, case-control studies are more efficient with rarer health outcomes, and CDI has a low prevalence of around 15 cases per 10,000 Americans.9 We will aim to study around 2,200 cases and 8,800 controls in the Twin Cities metro area. This number of cases will help ensure we have a significant number of patients taking each of the 12 classes of antibiotics we are measuring.
Population source: i. Inclusion …show more content…

We understand that since we are essentially testing for 12 different groups, the chances of calculating false positives are high, which is why the tests for antibiotics other than the 3 antibiotics in our hypothesis are purely explanatory. Furthermore, we are comparing the relative effects of certain antibiotics, rather than testing the absolute effect of individual classes of antibiotics. iii. Accounting for potential confounders:
Age: We will match each case to four controls in the same hospital on the basis of age in order to account for age as a potential confounder. Age will be classified into two categories, 65 years old and above, and under 65 years old, due to strong evidence indicating that CDI is much more common in those older than 65.
Duration of antibiotic use: We will use conditional logistic regression models (1 per antibiotic class) to account for the effects of how longer or shorter durations of antibiotic use affect CDI infection while also taking into account age, with duration of antibiotic use on the x-axis and probability of CDI on the y-axis.
Comorbidity: We will account for the possible effects of comorbidities on CDI in our discussion

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