What type of studies is categorized as Level III evidence?

Level III evidence is typically associated with case-control studies. These studies are observational in nature and compare individuals who have a specific outcome or condition (in this case, heart failure) to those who do not have that outcome, looking back to identify possible contributing factors or risk factors. Their design allows researchers to gather data on potential correlations and identify patterns, but they do not establish causal relationships as effectively as higher-level evidence.

This level of evidence is valuable in clinical practice because it provides insight into associations that can lead to further research and understanding. Since case-control studies are often one of the first steps in investigating an emerging clinical question, they play a crucial role in informing clinical decisions and guidelines, particularly when randomized controlled trials or systematic reviews are not yet available.