AtlasSession 4L12: Introduction to measurement errors and diagnostic test accuracy studiesp.40–49
Surrogate outcomes
Fig. 1
MSC injection for knee osteoarthritis: MRI cartilage volume at 1 year vs knee-replacement-free survival at 10 years (share of the promised effect)
Fig. 1: knee osteoarthritis wears away the cartilage seen on MRI, and that decides how long the knee lasts without replacement; the injection acts on the cartilage. The ideal path: cartilage is the only way the arthritis harms the knee. Follow-up 10.0 years. MRI: cartilage up. Knees: about the same gain.
- Cartilage on MRI
- up: the full gain
- Knees lasting without replacement
- about the same gain
Causal Diagram Lab · First look
Level 1 · First look · Lecture 12 · p.40–49
Explain what a stand-in outcome is, why researchers use one, and how it can mislead.
Explain what a surrogate outcome is, its advantages, the two conditions for using it as a therapeutic target, and the three routes by which it misleads.
Match stats vs the score (the step you are on)
A team can have most possession and corners and still lose.
A team can have most of the possession and corners and still lose: the match stats only stand in for the score. Here cartilage on MRI stands in for how long the knee lasts. Cartilage on MRI: up: the full gain; knees lasting without replacement: about the same gain.