Case series – Insights on value and use
How to cite this article: Koikkara KA, Hegde S, Keshava SN. Case series – Insights on value and use. Case Rep Clin Radiol. 2024;2:1-2. doi: 10.25259/CRCR_3_2024
Manuscripts in medical journals are published in a spectrum of formats ranging from original research to individual case reports. Among these, a “case series” is a lesser understood and possibly underutilized form of research methodology. It can be interpreted in various ways and we aim to clarify both definition and utility.
A case series cannot be considered merely a combination of case reports. It is an observational and descriptive research methodology. At its bones, a case series is a collection of cases with a common factor or outcome. The cases may or may not have common exposure factors and can be selected prospectively or retrospectively. Dekkers et al. infer that the absence of subjects without the specified “outcome” means that absolute risk cannot be calculated.[1-4]
To offer perspective, cohort studies will follow a group of exposed/unexposed subjects to study the possibility of an outcome. This permits the calculation of absolute risk (as well as relative risk if controls are included).[1,5]
Over 3 cases are required for a case series to be accepted as research. It can include from 3 to 100 cases, however, case series is not mentioned under the strengthening the reporting of observational studies in epidemiology (STROBE) guidelines.[7,8]
There is no formally defined process for case selection, and often includes any relevant case encountered by the researcher, not necessarily consecutive or over a defined period of time. This offers the opportunity for some amount of bias (in particular, selection bias).[2,9,10]
Although strong data-backed conclusions cannot be made from a case series, they contribute in other valuable ways. For example, often, this is the first way of presenting a new hypothesis or identifying new patterns. Subsequently, attention can be brought to the topic and further detailed research may be performed. Case series can aid in the design of future prospective trials and funding applications. It can lead to the recognition of new pathologies or uncommon presentations of common pathologies.
It is inexpensive and can be done in low-resource settings with ease. In view of straightforward methodology, a case series can also be published rapidly for new pathologies requiring urgent study. For example, during Covid-19, information about the clinical presentation, virology, and management of complications were essential to be disseminated quickly.[11,12] The source of life-threatening hemoptysis in post-Covid-19 patients was from pulmonary pseudoaneurysms, unlike bronchial arteries found in a post-tubercular squeal. Embolization could be planned accordingly.
HOW TO PROCEED WITH WRITING A CASE SERIES
Cases are identified by those that present an unusual clinical situation or offer a novel diagnostic or therapeutic method. A challenging clinical scenario that is managed can also be useful. It is ideal for cases to be collected rapidly, as this avoids any confounding factors that are unknown. It is important to include detailed descriptions of patient profiles, diagnostic findings, and interventions. It is prudent to address any potential bias.
Gagnier et al. have drafted the CARE guidelines (case reports) to provide a structure to the writing of a case series. It provides a checklist to ensure that all requirements are met and reporting standards are maintained. The framework reinforces the importance of providing a detailed description of any intervention to ensure reproducibility. The available literature must be summarized. Despite formal statistical analysis being impossible, authors may summarize or interpret the available data.
There is no uniformity regarding the approvals from the ethics or research board. We believe that a formal approval mentioned by the Sage publishers would enhance the value of the publication.
In the Indian medical profession, a case series has gained traction as it is now recognized by the National Medical Council (NMC) for the promotion of faculty. It is often the first exposure of medical professionals to publication. Radiology and broad-spectrum journals that accept case series include JCIR, IJRI, and CRCR.[7,18,19]
In summary, case series are not to be overlooked as a futile research methodology. They offer a wide range of benefits and significantly add to the knowledge pool. In addition, they can guide further formal research. It is prudent to select cases with care and describe the contribution of the information offered. The readers would benefit if more medical journals included the format. Due recognition by the authorities overseeing the academic performance of medical faculty is needed.
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