Chapter 7: Case Reports and Case Series

CHAPTER OBJECTIVES

• Discuss the objectives of case series and case reports

• Outline the necessary components of case reports

• Describe design and methodology of case series studies

• Evaluate strengths and weaknesses of case reports and case series

• Evaluate the results reported in case reports and case series

KEY TERMINOLOGY

• Case report

• Case series

• Publication bias

• Reliability

• Validity

INTRODUCTION

Case reports and case series are descriptive studies that recount a patient scenario complete with pertinent medical information such as laboratory values, medications, and diagnoses.^1,2 A case report includes a detailed discussion of a unique medical scenario of a single case or event in light of the currently available literature and provides an evaluation of the findings.³ Case series describe “a group of patients with similar diagnoses or undergoing the same procedure followed over time.”⁴ Although case reports and case series are at the lower end in the hierarchy of evidence, they provide valuable information to practitioners and policy makers.¹ In fact, five of the “51 Landmark Articles in Medicine” identified over a 150-year period were case reports.^5–7

With increasing emphasis on randomized studies for evidence-based medicine, some have come to question the need and utility of case reports and case series.^8,9 Over the last several years, the number of published case reports has declined due to the perception that they are anecdotal and limited in their ability to be generalized.⁵ In addition, publication costs, limitations in print space, need for peer reviewers, journal competition, and emphasis on the impact factor have brought about a decrease in number of case reports published.^5,10 However, journals exclusively publishing case reports have been developed and include the Journal of Medical Case Reports and Clinical Case Reports. These journals recognize the importance and need for case report literature.¹¹ Despite the need for well-designed studies, case reports have provided significant information that has helped to advance medical treatment.^5–7 Case reports have been found to be a viable source for identifying unexpected or uncommon occurrences, previously unknown conditions, new adverse drug reactions (ADRs), and innovative indications for medications.⁹ This chapter will provide a description of case reports and case series including, for each, a definition, characteristics, study design features, writing guidelines, strengths/limitations, and points for critical evaluation.

CASE REPORTS

Case Report Definition

Case reports are the most basic form of medical evidence that often provides the first suspicion that an issue exists.^9–10,12 A case report is a brief report of clinical characteristics or course from a single clinical subject or event without a comparison.^3,6 This form of literature only serves to provide a description of a situation and is not intended to lead to a conclusion or answer a hypothesis.^1...