Select a Community
Are you sure you want to trigger topic in your Anconeus AI algorithm?
You are done for today with this topic.
Would you like to start learning session with this topic items scheduled for future?
A study consisting of 1000 non-diabetic subjects; 500 patients with a BMI > 40 and 500 patients with normal BMI, followed for diagnosis of diabetes over their life time
13%
14/108
A study consisting of 500 patients with diabetes and 500 patients without diabetes comparing BMI of subjects in both groups
57%
62/108
A study consisting of 1000 genetically similar mice; 500 randomized to diet to maintain normal weight and 500 randomized to high caloric intake with the outcome of diabetes rates in both groups after 1 year
2%
2/108
A study of 1000 patients with BMI > 40 with diabetes; 500 randomized to inpatient diet and exercise with goal BMI <25, and 500 randomized to no treatment with an outcome of glycemic control without medication after 1 year
3%
3/108
A study of 1000 patients comparing rates of diabetes diagnoses and BMIs of diabetic and non-diabetic patients
14%
15/108
Select Answer to see Preferred Response
The "odds ratio" is ratio of (the odds that a case was exposed to a risk factor) to (the odds that a control was exposed to a risk factor). The results of case-control studies (Answer 2) are described as odds ratios. Odds is the probability that an event will happen divided by the probability that the event will not happen. For example, if there is a 10% chance that a flight will be cancelled, the odds that it will be cancelled are 0.1/0.9, or 0.11. With respect to a 2x2 chart (Illustration A), the odds that a case is exposed is (a/c), and the odds that a control is exposed is (b/d). Therefore, the "odds ratio" is (a/c):(b/d), or (a/c)/(b/d), or (a*d)/(b*c). As discussed in Gordis, odds ratios are less clinically useful than relative risk because they cannot be used to calculate absolute risk of an individual developing the disease without also knowing the incidence of disease in the exposed and unexposed groups. However, odds ratio can be used as an estimate of relative risk if the frequency of the disease is low, and the cases and controls studied are representative of their respective populations. Illustration A shows a template for a 2x2 table used to calculate odds ratios or relative risk depending on the study design. Incorrect Answers: Answer 1: This is an example of a cohort study. Although cohort studies can be summarized in terms of odds ratios, they are generally describe by relative risk, as it more clinically useful information. Answer 3: The results of an experiment in a model organism can not be extrapolated to odds ratios in humans. Answer 4: This is a randomized controlled trial, which are described in terms of relative or absolute risks. Answer 5: This is an example of a cross-sectional study, which can be used to calculate relative risk, as well as the prevalence of both the exposure (BMI > 40) and disease (diabetes). However, a limitation to the cross-sectional design is that large numbers are needed to avoid type II error if the prevalence of the exposure or disease are low.
2.8
(13)
Please Login to add comment