Evidence-appraisal glossary
Landmark Analysis
A survival method that picks a fixed time point after baseline, then compares outcomes only among people still event-free at that moment, grouped by their status up to it. It avoids crediting a group for time before an exposure could act.
Also called: landmark method.
When a characteristic or response is only known after follow-up begins, such as whether a patient responded by three months, comparing responders to non-responders from baseline manufactures immortal time bias. Landmark analysis sidesteps this by starting the clock at the landmark and including only survivors to that point, so everyone had a fair chance to be classified. The trade-off is that events before the landmark are excluded and the choice of landmark time can influence the result. It is a common fix, though modeling the exposure as time-varying is another.
Read the full Reading the Evidence blog.
This is a plain-language methodology definition for reading research. It is general education, not medical advice.