Reliability of serum biomarkers of inflammation from repeated measures in healthy individuals.

Navarro, Sandi L and Brasky, Theodore M and Schwarz, Yvonne and Song, Xiaoling and Wang, C Y and Kristal, Alan R and Kratz, Mario and White, Emily and Lampe, Johanna W (2012) Reliability of serum biomarkers of inflammation from repeated measures in healthy individuals. Cancer epidemiology, biomarkers & prevention : a publication of the American Association for Cancer Research, cosponsored by the American Society of Preventive Oncology. ISSN 1538-7755

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Abstract

BACKGROUND: Biomarkers of low-grade systemic inflammation are used to study the associations of inflammation with chronic diseases, including cancer. However, relatively little is known about the intra-individual variability of most of these measures. METHODS: Fasting serum samples, collected at baseline and the end of ≥3 week washout periods in a 4-diet crossover feeding trial, were used to measure the inflammatory markers high sensitivity C-reactive protein (hsCRP), interleukin (IL)-6, tumor necrosis factor (TNF)-α, IL-8 and soluble TNF receptor (sTNFR) I and II. Participants included 62 men and women for analyses of IL-6 and CRP and 56 for analyses of IL-8, TNF-α, and sTNFRs, aged 20-40, who were free of factors known to influence inflammation, e.g., chronic disease, medication use, heavy alcohol use, smoking and obesity (body mass index >30 kg/m2). Intraclass correlations (ICC) were estimated using random effects ANOVA, across all 4 time points (~6 weeks apart). RESULTS: ICCs for TNF-α and sTNFRI and II were very high: ICC=0.92, (95% CI: 0.89-0.96); 0.92, (95% CI: 0.88-0.95); and 0.90, (95% CI: 0.85-0.94), respectively. ICCs for IL-8 and hsCRP were 0.73 (95% CI: 0.63-0.83) and 0.62 (95% CI: 0.49-0.75), respectively. The ICC for IL-6 was considerably lower, ICC=0.48, (95% CI: 0.36-0.62). Three measures of IL-6 would be needed to achieve a reliability coefficient (Cronbach's alpha) of 0.75. CONCLUSIONS: With the exception of IL-6, reliability of all inflammatory markers in our panel was high. Impact: This suggests that a single measure accurately captures the short-term (e.g., 4-6 months) variability within an individual.

Item Type:	Article or Abstract
Additional Information:	The full text of this article will be freely available at the publishers site 12 months following official publication.
DOI:	10.1158/1055-9965.EPI-12-0110
PubMed ID:	22564866
NIHMSID:	NIHMS378007
Grant Numbers:	R01 CA142695, R01 CA70913, R56 CA70913, R25 CA94880, K05CA154337
Depositing User:	Library Staff
Date Deposited:	16 May 2012 19:54
Last Modified:	16 May 2012 19:54
URI:	http://authors.fhcrc.org/id/eprint/562

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