The Department of Health Services and Public Health authorities investigated an outbreak of severe gastrointestinal (GI) illness in Bayamón, Puerto Rico. A total of 25 individuals had been admitted to the city hospital with acute diarrhea, vomiting, bloating, and severe abdominal pain. A standardized questionnaire was used to collect relevant information related to person, place, and time from 25 individuals with severe GI illness and 75 individuals matched by age and sex who had been admitted to the same hospital for any reason other than GI illness. Preliminary results showed that 96% of the individuals with severe GI illness had eaten at a popular local restaurant 2-4 days before, and 4% of the individuals without GI illness had eaten at the same restaurant during the same period. Which of the following statements is correct about this study design?
A)The study collected relevant information related to person, place, and time using a standardized questionnaire, so it is a cross-sectional study
B)The study described individuals with and without severe GI illness in terms of person, place, and time, so it is a case series
C)The study estimated the incidence of GI illness among individuals who had eaten at a popular local restaurant the previous week and among those who had not, so it is a cohort study
D)The study gathered relevant information related to person, place, and time among individuals with and without severe GI illness, so it is a case-control study
E)The study matched individuals with and without severe GI illness by age, sex, and hospital admittance, so it is a randomized controlled trial

Question

The Department of Health Services and Public Health authorities investigated an outbreak of severe gastrointestinal (GI) illness in Bayamón, Puerto Rico.  A total of 25 individuals had been admitted to the city hospital with acute diarrhea, vomiting, bloating, and severe abdominal pain.  A standardized questionnaire was used to collect relevant information related to person, place, and time from 25 individuals with severe GI illness and 75 individuals matched by age and sex who had been admitted to the same hospital for any reason other than GI illness.  Preliminary results showed that 96% of the individuals with severe GI illness had eaten at a popular local restaurant 2-4 days before, and 4% of the individuals without GI illness had eaten at the same restaurant during the same period.  Which of the following statements is correct about this study design?
A)The study collected relevant information related to person, place, and time using a standardized questionnaire, so it is a cross-sectional study
B)The study described individuals with and without severe GI illness in terms of person, place, and time, so it is a case series
C)The study estimated the incidence of GI illness among individuals who had eaten at a popular local restaurant the previous week and among those who had not, so it is a cohort study
D)The study gathered relevant information related to person, place, and time among individuals with and without severe GI illness, so it is a case-control study
E)The study matched individuals with and without severe GI illness by age, sex, and hospital admittance, so it is a randomized controlled trial

Quizplus · Accepted Answer

Explanation: 11ec2b69_c109_3824_8f63_97d733437197_MD0005_00 In this study, patients with severe gastrointestinal (GI) illness are cases (individuals with disease) and patients with no GI illness are controls (individuals with no disease). A questionnaire was used to collect relevant information related to person, place, and time to compare exposure to ≥1 risk factors of interest (ie, dining at a local restaurant) between cases and controls. Because individuals were initially selected based on their status for a particular disease (ie, case: GI illness; control: no GI illness) and then categorized based on past exposure to a risk factor (ie, dining at a local restaurant), the study has a case-control design. (Choice A) In a cross-sectional study, a snapshot of a population is taken to estimate the prevalence of risk factors and disease simultaneously. Questionnaires are often used to collect data in cross-sectional studies, but they are also common in other study designs (eg, case-control study). (Choice B) In a case series, a small group of patients with a similar diagnosis or treatment is described at a point in time or followed over a certain period. This observational study has no comparison group, so it cannot establish associations between risk factors and disease. However, there is a comparison group in this study and an implicit purpose to evaluate association between exposure (ie, dining at a local restaurant) and disease (ie, GI illness). (Choice C) In a cohort study, 2 groups of individuals are initially identified as "exposed" or "nonexposed" according to their exposure status to a specific risk factor and then followed over time to assess development of the outcome (ie, incidence of disease). In this study, individuals were initially identified according to disease status (not exposure status); therefore, it is a case-control study, meaning that it is not possible to estimate incidence of disease. (Choice E) In a randomized controlled trial (RCT), participants are randomly assigned to ≥1 interventions to evaluate the effects of those interventions on outcomes of interest. Participants in a RCT may or may not be matched by certain characteristics (eg, age, sex, residence) to control for confounders. However, this study does not involve comparing treatments. Educational objective: Case-control studies can consider only 1 outcome (ie, disease) per study but can evaluate exposure to ≥1 risk factors.

The Department of Health Services and Public Health Authorities Investigated