American Board of Surgery Qualifying Exam (ABS QE) Practice Test

What is meant by Odds Ratio (OR) in clinical studies?

1. The odds of an event for individuals with a risk factor compared to those without

2. A method for measuring social desirability in responses

3. The difference in outcomes between different participant groups

4. A measure of data gain or loss in follow-up studies

The correct answer is: The odds of an event for individuals with a risk factor compared to those without

The Odds Ratio (OR) is a statistical measure used in clinical studies to compare the odds of an event occurring in two different groups. Specifically, it quantifies the odds of the event happening among individuals who have a specific risk factor compared to those who do not have that risk factor. This comparison allows researchers to understand the strength of the association between the exposure (risk factor) and the outcome of interest. In clinical research, the OR is particularly useful when dealing with case-control studies, where researchers look back at patients and assess their exposure to certain risk factors to determine if there is a higher frequency of a specific event in those with the risk factor relative to those without it. An OR greater than 1 suggests an increased risk associated with the exposure, while an OR less than 1 suggests a protective effect. Understanding the Odds Ratio is fundamental in interpreting the results of epidemiological studies, assisting in making informed clinical decisions based on the likelihood of events leading to various outcomes in differing populations.