How to design a good case series

Area of Science:

• Medical research methodology
• Clinical study design

Background:

• Case series are descriptive studies following patients with similar diagnoses or procedures.
• Patient and surgeon decisions, not experimental protocols, guide treatment in case series.
• This approach yields samples representative of typical clinical populations.

Purpose of the Study:

• To provide principles for designing, analyzing, and reporting case series.
• To illustrate these principles with examples from orthopaedic surgery.
• To clarify the role and limitations of case series in medical research.

Main Methods:

• The article outlines methodological principles for case series.
• It emphasizes the descriptive nature of the study design.
• Examples from orthopaedic surgical literature are used for illustration.

Main Results:

• Case series can generate hypotheses for further research, including randomized controlled trials.
• They reflect real-world clinical scenarios and patient populations.
• The study highlights that causal inferences regarding treatment efficacy cannot be drawn from case series.

Conclusions:

• Case series are valuable for hypothesis generation and understanding common clinical practices.
• Researchers must adhere to specific design, analysis, and reporting principles.
• The limitations of case series, particularly regarding causal inference, must be recognized.