Dafni2011 - Landmark Analysis at the 25-year Landmark Point

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Key takeaways

  • What landmark analyses are trying to address: In a naive analysis, response and nonresponse is compared regarding survival from the start of the study, but response status is not determined at baseline but during follow-up.
  • Sources of bias: Timing of response, impossibility of identifying a response in patients with shorter follow-up, increasing probability of response with longer follow-up. Response group classification is dependent on length of follow-up.
  • To remove these sources of bias: response after landmark time and deaths before landmark time are ignored.

“In the landmark method, a fixed time after the initiation of therapy is selected as a landmark for conducting the analysis of survival by response. Only patients alive at the landmark time are included in the analysis, separated into 2 response categories according to whether they have responded up to that time, that is, the landmark method ignores all responses after the landmark time and all deaths before that time.”

Drawbacks of landmark analysis

  • Dependence on choice of landmark
  • Lack of randomization in forming of groups