Cohort Study DesignSuppose that you have been hired by university student health services to design a prospective cohort study to assess the following hypothesis among undergraduate students: Raw sushi consumption increases the risk of acute diarrheal episodes. Be sure that your design addresses the following elements:1. Refine the study hypothesis so that it is as specific as possible and contains all elements of a “good” hypothesis.2. How will you find and recruit participants?o Are there any exclusion criteria that you would apply? 3. Will the study be retrospective or prospective? 4. How will you define the exposure of interest?o How will you collect the information on exposure? o How will you define the unexposed condition? 5. How will you define the outcome?o How will you collect information on acute diarrhea?o How often will subjects be evaluated/followed?6. What other information do you want to know about participants that may be related to the exposure of interest and/or the outcome (potential confounders)? Of these, what will you be able to collect and what will you be unable to collect?7. Which measures of disease frequency and association will you calculate?8. What are the strengths and limitations of your study? o What limitations could be removed by using a different study design? 9. What other information would you like to know in order to design this study?
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Introduction:
As a medical professor responsible for designing college assignments, it is crucial to ensure that theoretical concepts taught in lectures are tested in practice through research designs. In this hypothetical scenario, we will design a prospective cohort study to assess the hypothesis that raw sushi consumption increases the risk of acute diarrheal episodes among undergraduate students.
1. Refining the study hypothesis so that it is as specific as possible and contains all elements of a “good” hypothesis:
The specific hypothesis for our study will be as follows: Among undergraduate students, regular consumption of raw sushi increases the risk of acute diarrheal episodes compared to those who do not consume raw sushi.
2. Finding and recruiting participants and applying exclusion criteria:
We will recruit participants from undergraduate students at the university health services clinic. We will exclude participants who have a history of gastrointestinal illness or who are on medication that affects the gastrointestinal tract.
3. Prospective or retrospective study:
We will conduct a prospective cohort study.
4. Defining the exposure of interest and collecting information on exposure:
We will define the exposure of interest as regular consumption of raw sushi, and collect information on this through a self-reported dietary assessment questionnaire, as well as interviews with study participants.
5. Defining the outcome and collecting information on acute diarrhea:
The outcome will be defined as the development of acute diarrheal episodes lasting more than 24 hours. Information on this outcome will be collected through participant self-report and medical record review. Study participants will be followed up every week for a period of six months.
6. Other information related to potential confounders:
We will collect demographic data such as age, gender, and ethnicity, as well as information on other potential confounders such as antibiotic usage, prior antibiotic usage, and frequency of hand washing.
7. Measures of disease frequency and association:
We will calculate the incidence rate of acute diarrheal episodes (per 1000 person-days) among those exposed to raw sushi and those not exposed. We will also calculate the relative risk, using non-exposed individuals as the referent group.
8. Strengths and limitations of the study and potential for using a different study design:
One of the strengths of this study is that it is prospective, allowing for the assessment of temporal relationships between exposure and outcome. However, self-report may lead to bias and there is a potential for loss to follow-up, leading to an underestimation of the incidence rate. A different study design that could address these limitations is a randomized controlled trial.
9. Additional information required for study design:
Additional information required includes sample size calculation, statistical analysis plan, and ethical considerations such as informed consent and participant confidentiality.
