In a prospective cohort study, what is followed forward in time?

In a prospective cohort study, researchers select a group of participants based on their exposure status and then follow them over time to observe outcomes. This forward-looking design allows for the assessment of how specific exposures might influence the development of diseases or other health outcomes.

Choosing outcomes based on exposure status is crucial because the study aims to establish a temporal relationship between an exposure (which could be a lifestyle factor, medication, environmental influence, etc.) and the resulting health outcome. By tracking outcomes in participants who were initially categorized according to their exposure, researchers can determine the incidence of disease or other health effects over time. This design is valuable in identifying causal relationships and measuring the strength of these associations, often expressed through measures like relative risk.

The other options do not accurately describe what is tracked in a prospective cohort study. While controls for disease and prior exposures may be relevant factors in the overall research, they do not encapsulate the core focus of what is being monitored as the study progresses. Incidence and odds ratios are statistical measures derived from the outcomes, but they do not represent the forward tracking aspect of the cohort itself.