A case report is generally considered a type of
anecdotal evidence. Given their intrinsic
methodological limitations, including lack of
statistical sampling, case reports are placed at the bottom of the
hierarchy of clinical evidence, together with
case series. Nevertheless, case reports do have genuinely useful roles in
medical research and
evidence-based medicine. In particular, they have facilitated recognition of new diseases and adverse effects of treatments. For example, the recognition of the link between administration of
thalidomide to mothers and malformations in their babies was triggered by a case report. Case reports have a role in
pharmacovigilance. Whereas
randomized clinical trials usually only inspect one variable or very few variables, rarely reflecting the full picture of a complicated medical situation, the case report can detail many different aspects of the patient's
medical situation (e.g.
patient history,
physical examination,
diagnosis,
psychosocial aspects, follow up). Because typical, unremarkable cases are less likely to be published, use of case reports as scientific evidence must take into account
publication bias. Some case reports also contain an extensive review of the relevant literature on the topic at-hand (and sometimes a
systematic review of available evidence). Reports adopting this sort of approach can be identified by terms such as a "case report and review of the literature". Reports containing broader active research such as this might be considered
case studies in the true definition of the term. Case reports can also play a relevant role in medical education by providing a structure for
case-based learning. A particular attraction of case reports is the possibility of quick publication (with respect to more extensive studies such as randomized control trials), allowing them to act as a kind of rapid short communication between busy clinicians who may not have the time or resources to conduct large scale research. == Reporting guidelines ==