Researchers want to explore the association between selective serotonin reuptake inhibitor (SSRI) use and pulmonary tuberculosis. A random sample of subjects age 20-84 with newly diagnosed pulmonary tuberculosis and an independent random sample of subjects without pulmonary tuberculosis are enrolled in the study. Subsequently, subjects who never had a prescription for an SSRI are defined as "never users," and those who have had a prescription for an SSRI are defined as "users." The study compares the frequency of SSRI use in subjects with and without a diagnosis of pulmonary tuberculosis and determines that SSRI use is not associated with pulmonary tuberculosis. Which of the following best describes the design of this study?

Question

Researchers want to explore the association between selective serotonin reuptake inhibitor (SSRI) use and pulmonary tuberculosis.  A random sample of subjects age 20-84 with newly diagnosed pulmonary tuberculosis and an independent random sample of subjects without pulmonary tuberculosis are enrolled in the study.  Subsequently, subjects who never had a prescription for an SSRI are defined as "never users," and those who have had a prescription for an SSRI are defined as "users."  The study compares the frequency of SSRI use in subjects with and without a diagnosis of pulmonary tuberculosis and determines that SSRI use is not associated with pulmonary tuberculosis.  Which of the following best describes the design of this study?

Quizplus · Accepted Answer

11ec160b_372f_4a24_9249_e72bdda902c8_MD0001_00 Research studies are broadly classified as having an observational or experimental design depending on the control the researcher has over the independent variables (eg, exposure to risk factors, treatments). In observational studies (eg, case series, case-control studies, cohort studies, cross-sectional studies), the researcher has no control over the independent variables (eg, exposures, risk factors). In experimental studies (eg, randomized controlled trials), the researcher controls and randomly assigns the independent variables (eg, treatments, interventions). A case-control study is an observational design in which potential participants are initially identified as cases or controls according to the dependent variable or outcome (eg, disease of interest). In the study described above, subjects age 20-84 newly diagnosed with pulmonary tuberculosis are cases, and subjects without pulmonary tuberculosis are controls. Once cases and controls are identified, the presence of past exposure to ≥1 risk factors of interest is determined in each group. In this study, the risk factor is selective serotonin reuptake inhibitor (SSRI) use ("never users" are subjects who never had a prescription for an SSRI, and "users" are subjects who have had a prescription for an SSRI). Finally, the frequency of exposure to the risk factor is compared between cases and controls to estimate the association between the risk factor and the outcomes. Conducted as designed, this study can determine if SSRI use is associated with pulmonary tuberculosis. (Choice B) In contrast to participants in a case-control study, who are selected based on outcome status (eg, presence or absence of tuberculosis), participants in a cross-sectional study are randomly selected from a population of interest (eg, random sample from a region with high tuberculosis prevalence) and then simultaneously categorized according to risk factor (eg, SSRI use) and outcome (eg, tuberculosis) status. The goal is to determine prevalence by providing a snapshot of the population. (Choices C and E) In a cohort study, 2 groups of individuals (ie, cohorts) are initially identified based on their exposure status to a specific risk factor (eg, SSRI use) rather than based on their outcome status (eg, pulmonary tuberculosis), as seen in this example. These 2 cohorts are then followed over time (ie, prospectively) to assess development of the outcome. Sometimes the exposure status is determined retrospectively, typically using medical records, and patients are tracked from the point of exposure onward. (Choice D) A randomized controlled trial follows individuals who have been randomized to either a treatment arm or a control arm and compares the effect of the intervention. Educational objective: A case-control study is an observational study design; it begins with individuals who have the outcome (cases) and compares them with individuals who do not have the outcome (controls) according to history of exposure to ≥1 risk factors. __________ References: Epidemiology in practice: case-control studies. (http://www.ncbi.nlm.nih.gov/pubmed/17492047)

Researchers Want to Explore the Association Between Selective Serotonin Reuptake