Many different types of studies may be used in acute care research and for research in emergency situations.
Randomized Clinical Trial - This type of study is the "gold standard" for testing a new drug or new procedure. This is also the best way to compare two competing therapies. Subjects are assigned by chance to receive one treatment or the other. All other aspects of care are unchanged. Ideally, the providers and the subject are "blinded" - they do not know which drug or device was used. Blinding prevents any special treatment for subjects who get one or another therapy. In emergency settings, when the treatment under study must be delivered quickly, this type of study will often use an Exception from Informed Consent.
Before-and-After Study - This study design is very common in emergency care research. Essentially, a new therapy or drug is introduced into clinical practice and offered to ALL patients. Outcomes for subjects treated BEFORE the introduction are compared to outcomes for subjects treated AFTER the introduction. Usually investigators believe the new therapy is beneficial and should be offered to everyone. Results from this type of study are tricky to interpret because many parts of medical care can change over time, and as a result of the new therapy. Therefore, it is usually impossible to determine if the new therapy or drug was the only factor. In emergency settings, this type of research is often conducted as a Quality Improvement project, or sometimes using an Exception from Informed Consent.
Observational Study - This study design does not change medical care. Instead, extra information is collected to learn about a disease, about how care is delivered, or about how a new monitoring device works. This approach is the primary way to field-test a new monitor or instrument. Epidemiological studies also collect observational information prospectively. Because the research is usually "minimal risk," this type of research is often conducted using a Waiver of Informed Consent in emergency settings.
Cohort Study - This type of study collects information about subjects who were exposed to some intervention or situation. It also might include collecting information about subjects who had similar outcomes or were diagnosed with similar problems. In many cases, it is possible to identify a cohort of subjects from Observational Studies, and then ask this cohort for informed consent to continue monitoring them.