Analytical and biological variability in biomarker measurement in the Hispanic Community Health Study/Study of Latinos.

Background Biomarker variability, which includes within-individual variability (CV I ), between-individual variability (CV G ) and methodological variability (CV P + A ) is an important determinant of our ability to detect biomarker-disease associations. Estimates of CV I and CV G may be population specific and little data exists on biomarker variability in diverse Hispanic populations. Hence, we evaluated all 3 components of biomarker variability in the Hispanic Community Health Study/Study of Latinos (HCHS/SOL) using repeat blood collections (n = 58) and duplicate blood measurements (n = 761–929 depending on the biomarker). Methods We estimated the index of individuality (II) ((CV I + CV P + A ) / CV G ) for 41 analytes and evaluated differences in the II across sexes and age groups. Results Biomarkers such as fasting glucose, triglycerides and ferritin had substantially higher inter-individual variability and lower II in HCHS/SOL as compared to the published literature. We also found significant sex-specific differences in the II for neutrophil count, platelet count, hemoglobin, % eosinophils and fasting glucose. The II for fasting insulin, post oral glucose tolerance test glucose and cystatin C was significantly higher among the 18–44 y age group as compared to the 45 + y age group. Conclusions The implications of these findings for determining biomarker-disease associations in Hispanic populations need to be evaluated in future studies. [ABSTRACT FROM AUTHOR]