Ecological Studies and Cardiovascular Outcomes Research

Ecological studies have played an increasingly important role in the field of cardiovascular outcomes research and are increasingly attracting the attention of policy makers, health system managers, clinicians, and the public. We have illustrated in this review some examples of how ecological research methods can be used to identify and answer important policy and research questions that might not be identified or answered using alternative study designs. The primary "strength" of many ecological studies is that they are often the only way to answer a given scientific question. However, as many of these examples show, ecological studies can generate many "hypotheses," but their findings are often not conclusive and need careful interpretation and further investigations. Investigators should always be cognizant of the possibility of an ecological fallacy whereby potentially misleading causal inferences might be generated. Ecological studies of groups and studies of individuals complement one another, and both have an important role to play in increasing our understanding of how best to improve the outcomes of cardiovascular patients. © 2008 American Heart Association, Inc.