What are Case Reports and the Involvement of Case Series in Epidemiology?

A case report thoroughly accounts for a patient’s diagnosis, therapy, response to treatment, and post-treatment follow-up. A case series is an assortment of case studies on patients who received the same treatment. In most case reports and case series, demographic information on the patient(s) includes age, gender, and ethnic origin.

Introduction

The case series is considered a systematic inquiry aiming to add to generalizable knowledge (i.e., research) when more than three patients are provided. Therefore submission to the IRB is necessary. A written HIPAA consent from the patients or their legally authorized representatives to use and share their Protected Health Information should be acquired for all case reports and case series. The only exception to the requirement for obtaining authorization is if the author of a case report or case series believes that the information is not identifiable; in this case, the author must seek an expert opinion about the magnitude of the risk of identifying an individual from the Privacy Officer at Boston Medical Center or the HIPAA Privacy Officer of Boston University.

The HIPAA permission should be included in the consent form that the IRB evaluates for case reports or case series with more than three patients. Authors should create a permission form using the following templates for case reports or case series with three or fewer patients and arrange for review as described below. Customise the Scientific Literature review services in the template for the individual case report or case series. Please note that a personal representative, the administrator or executor of the patient’s estate, is required for deceased patients.

Categories of Descriptive Epidemiology

Case Reports

A case report is a comprehensive account of the incidence of a disease in a single person. Unusual aspects of the case may point to a new theory regarding illness origins or processes.

Example: Possible Transmission of Acquired Immunodeficiency in an Infant through Blood Products

It was not proven that AIDS could be spread by blood or blood products in April 1983. A child born with Rh incompatibility required blood from 18 donors over eight weeks and then suffered rare recurring infections with opportunistic organisms like Candida. The T cell count of the baby was low, indicating AIDS. Although there was no history of immunodeficiency in the family, one of the blood donors was discovered to have died of AIDS. As a result, the researchers hypothesised that AIDS might be spread through blood transfusions.

Case Series

A case series is a report that details the features of a group of people whom all have the same sickness or condition. Common characteristics within the group might lead to the illness causation hypothesis. The “series” might be tiny (as in the example below) or massive (as in the example below) (hundreds or thousands of “cases”). However, the most significant flaw is the lack of a comparison group. As a result, similar characteristics may propose hypotheses, but these must be validated in some way before a relationship can be regarded as legitimate.

Example: Discovery of HIV in the United States

In 1980–1981, four previously healthy young men were diagnosed with Pneumocystis carinii pneumonia, an uncommon “opportunistic” illness previously exclusively found in immune-compromised persons with genetic diseases or those who had had chemotherapy. Although there was no evidence of primary immunodeficiency in the medical histories, all four individuals exhibited reduced immune responses and low T cell counts. These uncommon infections raised the likelihood of a previously undiagnosed illness. All four men were sexually active homosexuals. The authors of the case series reported in the New England Journal of Medicine thought this caused the immunological dysfunction.

Strengths of Case Reports and Case Series

· They are rapid and affordable, and frequently based on existing data.

· They can identify and explain new and developing health issues.

· They may form hypotheses based on group commonalities.

· They might provide information on disease processes.

Limitations of Case Reports and Case Series

· There isn’t a control group.

· The timing of the exposure and the health consequence is frequently ambiguous, i.e., it is not always apparent that the direction came before the outcome.

References

1. Gutiérrez, Félix, et al. “Osteonecrosis in patients infected with HIV: clinical epidemiology and natural history in a large case series from Spain.” JAIDS Journal of Acquired Immune Deficiency Syndromes 42.3 (2006): 286–292.

2. Chegini, Zahra, et al. “Epidemiology, clinical features, diagnosis and treatment of cerebral mucormycosis in diabetic patients: a systematic review of case reports and case series.” Mycoses 63.12 (2020): 1264–1282.

García‐Doval, I., et al. “Optimising case reports and case series: guidance on how to improve quality.” British Journal of Dermatology 178.6 (2018): 1257–1262.