Summary

Success in biomarker discovery?

In order to improve success in biomarker discovery, researchers need to consider the variability between studies that has led to inconsistent findings and irreproducibility.
Within- and between-study variabilities have resulted in estimates with low precision, false negatives and false positives, and non-repeatability.
The focus of current research should be adjusted to broaden the scope outside of a limited number of biochemical compounds.

Taking CRGP as a potential biomarker, a full literature search should be conducted to identify all available evidence that investigates factors that affect CRGP levels.
Overall, a better understanding of confounding factors is of importance for the design of future studies investigating exposure associations.
Sex distribution, age, aura, menstrual cycle, study quality, specimen source, blood specimen and blood sampling site and timing were identified as potential confounders.^1,2
Further studies are needed to confirm they are potential confounders.

Restriction, matching and randomization are methods often employed by investigative studies to control for confounding factors but there are often consequences to employing these methods.
Standardization and multivariate analyses are methods that could lead to a better understanding of confounding factors and improve biomarker discovery.