Case-control study

    This is a type of observational study in which two groups of people are compared in order to determine characteristics associated with a specific condition or outcome. The first group is made up of individuals who have a condition or outcome of interest, known as cases. The second set of people, who do not have the condition, are called controls.[1]

    Summary

    Though the terms ‘case study’ and ‘case report’ have been used interchangeably in the past, their difference lies in the approach. Case reports contain a detailed description of a single patient’s unique clinical findings (diagnosis, treatment, and outcome). Case studies, on the other hand, tend to involve a much deeper qualitative exploration into the case or cases involved. [2] Case series involve a small collection of patients who share a common clinical feature, such as a rare condition or response to a novel therapy.[3] In short, case studies are a more qualitatively deeper cousin of the case report, while case series are a collection of more closely related case report siblings.

    The lack of a control group plus the descriptive approach of all three study types means that they can detail observations, but they cannot establish causation. Even in instances where causation may seem likely, the small number of patients involved means they are not suitable for application to a broader population. However, they are each valuable to help clinicians learn from rare or unusual instances in practice.

    References

    1. ^Lewallen S, Courtright PEpidemiology in practice: case-control studies.Community Eye Health.(1998)
    2. ^Alpi KM, Evans JJDistinguishing case study as a research method from case reports as a publication type.J Med Libr Assoc.(2019 Jan)
    3. ^Murad MH, Sultan S, Haffar S, Bazerbachi FMethodological quality and synthesis of case series and case reports.BMJ Evid Based Med.(2018 Apr)
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