A study investigates the prevalence of ischemia in 512 patients with chest pain undergoing stress testing. Only patients with negative cardiac enzymes and nondiagnostic electrocardiogram changes are included. Myocardial perfusion imaging for ischemia and coronary artery calcification (CAC) score are obtained for each participant. The following results are reported: Which of the following best describes the study design?
A)Case-control study
B)Case series
C)Cross-sectional study
D)Prospective cohort study
E)Randomized clinical trial

Question

A study investigates the prevalence of ischemia in 512 patients with chest pain undergoing stress testing.  Only patients with negative cardiac enzymes and nondiagnostic electrocardiogram changes are included.  Myocardial perfusion imaging for ischemia and coronary artery calcification (CAC) score are obtained for each participant.  The following results are reported: Which of the following best describes the study design?
A)Case-control study
B)Case series
C)Cross-sectional study
D)Prospective cohort study
E)Randomized clinical trial

Quizplus · Accepted Answer

Explanation: 11ec2b69_c0ea_8c61_8f63_dbb54bc5ccde_MD0005_00 This study compares the prevalence (at a specific point in time) of ischemia within different categories of coronary artery calcification (CAC) scores. This snapshot corresponds to a cross-sectional design. Cross-sectional studies can be descriptive or analytic (can infer but not prove causation). Subjects are assessed for the occurrence of risk factor exposure and for the presence of disease; some will not have been exposed or have the disease. (Choice A) A case-control study categorizes patients with and without a specific disease (eg, ischemic heart disease) and compares the risk factor frequency (eg, CAC score) between the 2 groups. (Choice B) A case series is a group of case reports regarding individual patients who had similar clinical manifestations or received similar treatment. Each individual case is typically described in detail. Case reports are sometimes used in rare diseases or novel treatments. (Choice D) A prospective cohort study would follow individuals who do not have the disease/outcome of interest (eg, ischemic heart disease) and who may or may not have a certain risk factor (eg, elevated CAC scores) over time; the study would then assess disease development (ie, incidence of ischemic heart disease). (Choice E) A randomized clinical trial would follow individuals who have been randomized to either a treatment arm (or arms) or a control arm and compare the effect of the intervention. Educational objective: In cross-sectional studies, individuals are assessed at a specific point in time to determine whether or not they have a certain risk factor and a certain disease of interest. References: Observational research methods. Research design II: cohort, cross sectional, and case-control studies. (http://www.ncbi.nlm.nih.gov/pubmed/12533370)

A Study Investigates the Prevalence of Ischemia in 512 Patients