[Roaming through methodology. XXV. Outcome measures, surrogate outcomes, and intermediate measures]

Area of Science:

• Clinical medicine
• Biostatistics
• Epidemiology

Background:

• Clinical medicine strives to reduce disease burden.
• True outcome measures in clinical research, reflecting disease burden changes, are ideal but often costly or infeasible.
• Intermediate measures are frequently used as proxies for true outcomes.

Purpose of the Study:

• To discuss the role and evaluation of intermediate and surrogate outcomes in clinical research.
• To provide a framework for assessing the applicability of clinical trial measures.

Main Methods:

• Conceptual analysis of outcome measures in clinical research.
• Discussion of the relationship between intermediate measures, surrogate outcomes, and true disease burden.
• Presentation of criteria for evaluating the applicability of clinical trial measures.

Main Results:

• Intermediate measures offer practical alternatives when direct outcome assessment is not feasible.
• Surrogate outcomes are intermediate measures with a strong, validated relationship to true outcomes.
• The applicability of any measure depends on its truthfulness, discriminative ability, and feasibility.

Conclusions:

• Accurate assessment of disease burden is central to clinical medicine.
• Intermediate and surrogate outcomes are valuable tools but require rigorous validation and careful interpretation.
• Clinicians must critically appraise the relevance and applicability of study measures to their practice.