A study is designed to describe the manifestations of coronavirus disease 2019 (COVID-19) on imaging studies, particularly on computerized tomography (CT) scans. Eleven patients with COVID-19 are recruited for the study, and their CT findings are studied and characterized. Which of the following best describes this study design?

Question

A study is designed to describe the manifestations of coronavirus disease 2019 (COVID-19) on imaging studies, particularly on computerized tomography (CT) scans.  Eleven patients with COVID-19 are recruited for the study, and their CT findings are studied and characterized.  Which of the following best describes this study design?

Quizplus · Accepted Answer

Research studies are broadly classified as having an observational design or an experimental design depending on the control the researchers have over the independent variables. In observational studies (eg, case series, case-control studies, cohort studies, cross-sectional studies), the researchers have no control over the independent variables (eg, exposure to risk factors, treatments). In experimental studies (eg, crossover design, randomized controlled trials), the researchers control and randomly assign the independent variables (eg, exposure to risk factors, treatments). Case series is a descriptive observational study design in which a (generally small) group of patients with a similar diagnosis or treatment is described at a point in time or followed over a certain time period. Contrary to other observational designs (eg, cohort, case-control), a case series has no comparison group (Choices A and D). For this reason, a case series cannot establish associations between risk factors (eg, treatments) and outcomes (eg, diseases). In this example, the CT scan findings of 11 patients with coronavirus disease 2019 (COVID-19) are being studied. The study has no control group; therefore, it can only describe COVID-19 manifestations on imaging studies. (Choice C) A clinical trial is an experimental study in which patients are prospectively assigned to ≥2 interventions (often including a placebo or control treatment) to evaluate the effects of those interventions on outcomes of interest. (Choice E) A cross-sectional study is an observational study that assesses a population of interest (eg, all women of reproductive age) at a single point in time; it can be used to estimate disease prevalence and association with risk factors of interest. However, it is not used to characterize disease findings because subjects are not selected based on the presence of disease. Educational objective: A case series is a descriptive observational study design in which a group of patients with a similar diagnosis or treatment is described at a point in time or followed over a certain period. This study design has no comparison group; therefore, it cannot establish associations between risk factors (eg, treatments) and outcomes (eg, diseases).

A Study Is Designed to Describe the Manifestations of Coronavirus