Glossary · Methodology
Surrogate marker
In short
A surrogate marker is a measured value that stands in for what you are actually interested in — a lab value instead of the course of a disease. It is easier to measure, but it is not the same thing.
Whether someone lives longer or has a heart attack less often only becomes apparent after years and requires very large studies. A cholesterol level, the amount of fat in the abdomen or an IGF-1 level, on the other hand, can be measured within weeks. That is why many studies work with such stand-ins.
That is legitimate — as long as the gap is named. A marker moves; whether what counts moves with it is a second question that needs its own studies. The history of medicine knows enough cases in which the marker went in the right direction and mortality still rose.
In the BK-Score, this is the most common reason for medium human evidence despite a good mechanism: the stand-in is well documented, the endpoint behind it is not.
The marker moves, the function does not.
Where this comes up in the fact checks
- Tesamorelin – Visceral fat has been shown to be lowered and IGF-1 to be raised — this does not show a benefit for hard endpoints.
- NMN – The NAD+ level in the blood rises measurably; what follows from it is the open question.
- CGM (blood glucose sensor) – A flatter glucose curve is a measured value, not a health outcome.
Related terms: Primary endpoint · Visceral fat
Information only, not medical advice. The BK-Score is a subjective assessment according to disclosed rules – not a scientific evaluation. Scoring rules