In a cohort study, how is the odds of developing disease calculated?

In a cohort study, the calculation of the odds of developing a disease is focused on comparing the likelihood of disease occurrence between those who are exposed to a certain risk factor and those who are not exposed. The correct approach is to determine the odds in the exposed group and then contrast it with the odds in the non-exposed group.

Specifically, odds are computed by taking the number of individuals who develop the disease in each group and dividing it by the number of individuals who do not develop the disease in that same group. Thus, when you calculate the odds in the exposed group, you express it as the ratio of the probability of disease occurrence among the exposed to the probability of not developing the disease among the same population. Similarly, the odds in the non-exposed group is computed the same way.

The answer highlighting the odds in the exposed group divided by those in the non-exposed group effectively illustrates the comparison of the risk associated with exposure to the disease, allowing for a clearer understanding of how the exposure impacts the likelihood of developing the disease. This approach is fundamental in epidemiological studies as it helps in identifying and quantifying risk factors associated with certain health outcomes.