Case study and series
Differences in aims
A case study or case report is like a case series but it includes only one individual:
• The aim is to describe a single and unusual incident or case
A case series is a descriptive study involving a group of patients who all have the same disease or condition:
• The aim is to describe common and differing characteristics of a
particular group of individuals
Similarities
For both a case study and a case series:
• The aim is not to draw general conclusions
• It is not a true research study
• It may provide useful indications for further research
Example: a case study
An article published in The Lancet described the case of an 80-year old woman who presented with episodes of unconsciousness and disorientation over several years.1 During a subsequent episode she was found to have a blood glucose of 1.5 mmol/L (normal range 3.5–5.5 fasting).
Routine blood tests were normal and a 72-hour fast produced no
symptoms of hypoglycaemia (low blood sugar).
Further investigations led to the discovery of an insulin-secreting
tumour in the body of the pancreas. The tumour was producing excess insulin in response to glucose, therefore causing glucose-induced hypoglycaemia.
Example: a case series
An article published in Brain described a series of patients with pneumococcal meningitis.2 The paper reported the symptoms, complications, and outcome in 87 consecutive meningitis patients seen in a particular neurology department. The authors stated that their analysis can help doctors identify prognostic factors in patients, and can guide the design of future research studies.

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