Evidence-appraisal glossary
Case series
A descriptive report of the course and outcomes of a group of patients who share a diagnosis or received a similar treatment, with no comparison or control group.
Also called: clinical case series.
Case series are useful early signals: they can describe how a new treatment seemed to affect several patients or characterize an emerging condition, generating hypotheses for stronger studies to test. Because there is no comparison group and patients are usually not selected systematically, a case series cannot tell you whether the treatment caused the outcome or how it compares to doing nothing. Improvement reported in a series may reflect natural recovery, selection, or regression to the mean.
Read the full Reading the Evidence blog.
This is a plain-language methodology definition for reading research. It is general education, not medical advice.