Which of the following best describes retrospective studies?

Retrospective studies are characterized by their use of past data to investigate outcomes or trends. In these studies, researchers look back at existing records or data from prior time periods to analyze the effects of exposures or interventions on patient outcomes. This type of research allows for the examination of data without the need for new data collection, making it a valuable approach for quickly gaining insights from historical information.

In contrast, studies that use current data focus on information gathered in real-time, which differs fundamentally from the retrospective analysis. Cohort analysis can be part of retrospective studies but does not exclusively define them, as cohort studies can also be prospective. Similarly, while evaluating patterns of care may be a component of retrospective studies, it does not adequately capture the essence of defining a study as retrospective, which specifically emphasizes the use of previously collected data.