![]() ![]() Thus, the group looked is 0.57 times as likely to be overweight or obese if an individual performs moderate exercise. In this example, the event is "overweight or obese, " and the exposure is "moderate exercise." Then relative risk is calculated as: A survey of a group of people finds that 40% of those who perform moderate exercise are overweight or obese, and 70% of those who do not perform moderate exercise are overweight or obese. Thus, it is 10.4 times more likely to have an upset stomach after taking the new medicine in this study than if you did not take the new medicine in the study.Įxposure can also provide benefits and decrease the risk of the event. Now we can calculate the relative risk of having an upset stomach (event) after taking the new medicine (exposure). Next, we calculate the probability of an upset stomach in the non-exposure group. Note the probability is the probability of having an upset stomach in all individuals in the exposure group, both those with and without an upset stomach who took the new medicine. Thus, the probability of having an upset stomach in the exposed group is as follows: Fourteen people have an upset stomach who were exposed, and 42 people do not have an upset stomach who were exposed. To calculate the relative risk (RR), first, calculate the probability of having an upset stomach with exposure to the new medication. In volunteers who did not take the medication, two people have an upset stomach, and 83 do not have an upset stomach. Fourteen of the volunteers who were given the new medicine have an upset stomach, and 42 of the volunteers who were given the new medicine do not have an upset stomach. Thus, smokers are 17 times more likely to develop lung cancer than non-smokers.Ī second example involves a study of a new medicine. ![]() If we hypothetically find that 17% of smokers develop lung cancer and 1% of non-smokers develop lung cancer, then we can calculate the relative risk of lung cancer in smokers versus non-smokers as: Relative Risk = (Probability of event in exposed group) / (Probability of event in not exposed group) Īn example will help clarify this formula. ![]()
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