Surrogate Endpoint

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Definition

A surrogate endpoint is a biomarker or measurement used in place of a direct clinical outcome to estimate treatment benefit. It is intended to substitute for outcomes such as survival, symptom improvement, or quality of life.

Correct Scientific Usage

Surrogate endpoints are used when true clinical outcomes take too long or are too costly to measure. Researchers distinguish between validated and unvalidated surrogates. For a surrogate to be valid, changes in the surrogate must reliably predict changes in the clinical outcome across multiple studies and interventions.

Common Misunderstandings

It is often assumed that improving a surrogate endpoint automatically means improved health outcomes. However, drugs can change biomarkers without providing real benefits. Not all surrogate endpoints are equally valid—some have strong evidence supporting them while others are speculative.

Why It Matters

Understanding the difference between a surrogate endpoint and a clinical outcome helps us evaluate clinical trials and drug approvals more accurately.

References

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