What type of study collects data retrospectively from medical records after a condition has developed?

The selected answer accurately identifies the type of study that involves collecting data after a condition has developed by examining existing medical records. Retrospective cohort studies specifically look back in time to analyze data from individuals who have experienced a particular outcome, allowing researchers to establish associations between exposure factors and health outcomes. This method is particularly beneficial for studying conditions that are rare or take a long time to develop, as it utilizes previously collected data rather than requiring new data collection over time.

In these studies, researchers can identify a cohort based on exposure status and then follow the outcomes that have already been recorded, making it a practical approach for understanding the relationship between exposure and the subsequent development of health issues. The design emphasizes investigating events that have occurred, which distinguishes it from other study types.