A group of sports physicians plans to conduct a case-control study to investigate a possible association between adolescent idiopathic scoliosis (AIS) and sacroiliac joint (SIJ) dysfunction in young athletes. The case group will consist of young athletes who were diagnosed with AIS during a regular checkup by a sports physician. Which of the following is the most appropriate control group for this study?

Question

A group of sports physicians plans to conduct a case-control study to investigate a possible association between adolescent idiopathic scoliosis (AIS) and sacroiliac joint (SIJ) dysfunction in young athletes.  The case group will consist of young athletes who were diagnosed with AIS during a regular checkup by a sports physician.  Which of the following is the most appropriate control group for this study?

Quizplus · Accepted Answer

11ec160b_3732_a587_9249_3f1fdf8b1fe6_MD0001_00 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). Once cases and controls are identified, the presence of past exposure to ≥1 risk factors of interest is determined in each group. Finally, the frequency of exposure to the risk factors is compared between cases and controls to estimate the association between the risk factors and the outcomes. If there is a statistically significant difference in the frequency of exposure to the risk factor between the 2 groups, it is likely that the risk factor in question is associated with the disease. In this example: The population of interest is young athletes. Therefore, both the cases and control groups must consist of young athletes (Choices F and G). The disease of interest (ie, what defines a case) is adolescent idiopathic scoliosis (AIS). Therefore, the cases must have AIS and controls must not have AIS (Choices A, B, and C). The risk factor of interest is sacroiliac joint (SIJ) dysfunction. Cases and controls must be selected irrespective of SIJ status because the presence of SIJ is what is compared between cases and controls (Choice E). Therefore, the cases are young athletes with a diagnosis of AIS irrespective of SIJ status; the controls are young athletes with no diagnosis of AIS irrespective of SIJ status because what determines whether the disease (ie, AIS) is associated with the risk factor (ie, SIJ) is the difference in the frequency of the risk factor between cases and controls. 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.

A Group of Sports Physicians Plans to Conduct a Case-Control