Coefficients of Variation

With coefficients of variation ~5%, you can see even the smallest changes in disease state and therapy effectiveness

Coefficient of Variation (CV) Values
	SomaScan® 11K Assay			SomaScan® 7K Assay
	Intra-Plate	Inter-Plate	Total	Intra-Plate	Inter-Plate	Total
Plasma	3.3%	3.0%	4.5%	3.6%	3.8%	5.3%
Serum	2.4%	2.4%	3.5%	2.7%	2.5%	3.8%

Reproducibility is fundamental to obtaining reliable and accurate research results. Lower coefficients of variation (CVs) mean greater confidence in a platform’s reproducibility – and, therefore, greater confidence in your data.

When it comes to biomarker discovery, higher technical variability — which results from higher CVs – means more samples are required to detect a statistically significant difference. Such assay noise can also limit measurements or discoveries, which can mean a loss in detectability or an obstruction of biological effect sizes.

We created the SomaScan Platform with a median CV of ~5%, which means researchers can use the fewest number of samples to detect the most minute biological changes. Without this level of precision, we believe these changes cannot be reliably tested in individuals, and clinical studies will require many more participants.

With coefficients of variation ~5%, you can see even the smallest changes in disease state and therapy effectiveness

SomaScan® 11K Assay Coefficient of Variation (CV) Values
	Intra-Plate	Inter-Plate	Total
Plasma	3.3%	3.0%	4.5%
Serum	2.4%	2.4%	3.5%

SomaScan® 7K Assay Coefficient of Variation (CV) Values
	Intra-Plate	Inter-Plate	Total
Plasma	3.6%	3.8%	5.3%
Serum	2.7%	2.5%	3.8%

Reproducibility is fundamental to obtaining reliable and accurate research results. Lower coefficients of variation (CVs) mean greater confidence in a platform’s reproducibility – and, therefore, greater confidence in your data.

When it comes to biomarker discovery, higher technical variability — which results from higher CVs – means more samples are required to detect a statistically significant difference. Such assay noise can also limit measurements or discoveries, which can mean a loss in detectability or an obstruction of biological effect sizes.

We created the SomaScan Platform with a median CV of ~5%, which means researchers can use the fewest number of samples to detect the most minute biological changes. Without this level of precision, we believe these changes cannot be reliably tested in individuals, and clinical studies will require many more participants.

Leading the industry with dependably low CVs

No other proteomic platform consistently provides median CVs as low as the SomaScan Platform.

Currently, researchers see CVs ranging from:
• 5-20% with proximity ligation assays that use polyclonal antibodies
• 10-20% with mass spectrometry

What CVs do you currently see with your proteomics platform?
Does that affect the number of samples you need to get meaningful data?

Talk to our scientific team about CVs

What is the benefit of CVs ~5%?

Median CVs ~5% yield an unmatched level of precision that allows researchers to reliably perform analysis and clinical studies with fewer participants than is required with other proteomic platforms.

Relative to the SomaScan Assay with a ~5% CV, a platform with CVs of about 10% would need approximately 2,300 more samples to detect a 1% difference in means compared to detecting that difference using the SomaScan Assay.

Midplex affinity-based
platforms show median CVs
close to 9% and 12%

The CDF plots reinforce not only the stability of the SomaScan Assay, but also illustrate how the low CVs distinguish the platform from other proteomic technologies.

Midplex Platforms CVs chart

What is the benefit of CVs ~5%?

Median CVs ~5% yield an unmatched level of precision that allows researchers to reliably perform analysis and clinical studies with fewer participants than is required with other proteomic platforms.

Relative to the SomaScan Assay with a ~5% CV, a platform with CVs of about 10% would need approximately 2,300 more samples to detect a 1% difference in means compared to detecting that difference using the SomaScan Assay.

Midplex affinity-based
platforms show median CVs
close to 9% and 12%

The CDF plots reinforce not only the stability of the SomaScan Assay, but also illustrate how the low CVs distinguish the platform from other proteomic technologies.

Midplex Platforms CVs chart

Curated CV research publications

Title	Author	Year	Journal	Volume	Issue	Pages	DOI	Accession number	Keywords	Abstract	All authors/Notes	Epub date
Analytical and Biological Variability of a Commercial Modified Aptamer Assay in Plasma Samples of Patients with Chronic Kidney Disease.	Dubin RF, et al.	2023	J Appl Lab Med							We carried out a study of the aptamer proteomic assay, SomaScan V4, to evaluate the analytical and biological variability of the assay in plasma samples of patients with moderate to severe chronic kidney disease (CKD).	Dubin RF, Deo R, Ren Y, Lee H, Shou H, Feldman H, Kimmel P, Waikar SS, Rhee EP, Tin A, Chen J, Coresh J, Go AS, Kelly T, Rao PS, Chen TK, Segal MR, Ganz P.	01/27/2023
Assessment of variability in the plasma 7k SomaScan proteomics assay	Candia J, et al.	2022	Sci Rep	12	1	17147	https://www.doi.org/10.1038/s41598-022-22116-0	36,229,504	Biomarkers/metabolism Humans *Proteomics/methods	SomaScan is a high-throughput, aptamer-based proteomics assay designed for the simultaneous measurement of thousands of proteins with a broad range of endogenous concentrations. In its most current version, the 7k SomaScan assay v4.1 is capable of measuring 7288 human proteins. In this work, we present an extensive technical assessment of this platform based on a study of 2050 samples across 22 plates. Included in the study design were inter-plate technical duplicates from 102 human subjects, which allowed us to characterize different normalization procedures, evaluate assay variability by multiple analytical approaches, present signal-over-background metrics, and discuss potential specificity issues. By providing detailed performance assessments on this wide range of technical aspects, we aim for this work to serve as a valuable resource for the growing community of SomaScan users.	Candia, Julian Daya, Gulzar N Tanaka, Toshiko Ferrucci, Luigi Walker, Keenan A eng ZIAAG000971-14/AG/NIA NIH HHS/ ZIAAG000349-01/AG/NIA NIH HHS/ England Sci Rep. 2022 Oct 13;12(1):17147. doi: 10.1038/s41598-022-22116-0.I	10/14/2022
Reproducibility and Variability of Protein Analytes Measured Using a Multiplexed Modified Aptamer Assay	Tin A, et al.	2019	J Appl Lab Med	4	1	30-39	https://www.doi.org/10.1373/jalm.2018.027086	31,639,705	Aged Atherosclerosis/blood/diagnosis Blood Proteins/analysis Equipment Design Female Glomerular Filtration Rate/physiology Humans Male Middle Aged Prospective Studies Proteomics/*instrumentation Reproducibility of Results	BACKGROUND: There is growing interest in the use of multiplexed aptamer-based assays for large-scale proteomic studies. However, the analytic, short- and long-term variation of the measured proteins is largely uncharacterized. METHODS: We quantified 4001 plasma protein analytes from 42 participants in the Atherosclerosis Risk in Communities (ARIC) Study in split samples and at multiple visits using a multiplexed modified aptamer assay. We calculated the CV, Spearman correlation, and intraclass correlation (ICC) between split samples and evaluated the short-term (4-9 weeks) and long-term (approximately 20 years) variability using paired t-tests with log-transformed protein concentrations and Bonferroni-corrected significance thresholds. We performed principal component (PC) analysis of protein analyte concentrations and evaluated their associations with age, sex, race, and estimated glomerular filtration rate (eGFR). RESULTS: The mean baseline age was 57 years at the first visit, 43% of participants were male and 57% were white. Among 3693 protein analytes that passed quality control, half (n = 1846) had CVs < 5.0%, Spearman correlations > 0.89, and ICCs > 0.96 among the split samples. Over the short term, only 1 analyte had a statistically significant difference between the 2 time points, whereas, over approximately 20 years, 866 analytes (23.4%) had statistically significant differences (P < 1.4 x 10(-5), 681 increased, 185 decreased). PC1 had high correlations with age (-0.73) and eGFR (0.60). PC2 had moderate correlation with male sex (0.18) and white race (0.31). CONCLUSIONS: Multiplexed modified aptamer technology can assay thousands of proteins with excellent precision. Our results support the potential for large-scale studies of the plasma proteome over the lifespan.	Tin, Adrienne Yu, Bing Ma, Jianzhong Masushita, Kunihiro Daya, Natalie Hoogeveen, Ron C Ballantyne, Christie M Couper, David Rebholz, Casey M Grams, Morgan E Alonso, Alvaro Mosley, Thomas Heiss, Gerardo Ganz, Peter Selvin, Elizabeth Boerwinkle, Eric Coresh, Josef eng HHSN268201100009C/HL/NHLBI NIH HHS/ HHSN268201700002I/HL/NHLBI NIH HHS/ N01HC55020/HL/NHLBI NIH HHS/ HHSN268201100005C/HL/NHLBI NIH HHS/ HHSN268201100006C/HL/NHLBI NIH HHS/ HHSN268201100007C/HL/NHLBI NIH HHS/ HHSN268201100008C/HL/NHLBI NIH HHS/ HHSN268201100011C/HL/NHLBI NIH HHS/ HHSN268201100012C/HL/NHLBI NIH HHS/ U01 HL096812/HL/NHLBI NIH HHS/ U01 HL096814/HL/NHLBI NIH HHS/ U01 HL096899/HL/NHLBI NIH HHS/ U01 HL096902/HL/NHLBI NIH HHS/ U01 HL096917/HL/NHLBI NIH HHS/ R01 HL134320/HL/NHLBI NIH HHS/ K01 DK107782/DK/NIDDK NIH HHS/ Research Support, N.I.H., Extramural Research Support, Non-U.S. Gov't England J Appl Lab Med. 2019 Jul;4(1):30-39. doi: 10.1373/jalm.2018.027086. Epub 2019 Jan 22.I	10/23/2019

Why coefficient of variation is
a critical metric

Want to move more quickly and efficiently toward your research goal? SomaLogic leads the field with reproducible CVs of ~5%. The SomaScan Platform has established and maintained low CVs, all while continuing to grow in measurable content. From more robust discovery potential to well-powered studies with fewer samples, the SomaScan Assay offers many notable advantages.

Download the white paper

SOMAmer^® Reagents yield precise, reproducible results

You can choose one of our SomaScan^® Panels to focus on a specific disease or research need, such as cytokines, cancer, NASH, inflammation, and more. Or customize your own panel.

See how SOMAmer Reagents work

Unlike polyclonal antibodies, these reagents are eternally consistent, which means dependable reproducibility that is superior to any other proteomic assay in the industry.

Ask us how greater precision could improve your research

LEARN FROM A COLLEAGUE

Assessment of variability and normalization methods using the plasma SomaScan® 7K Assay v4.1

Julián Candia, PhD, and Keenan Walker, PhD, presented the largest independent technical assessment of the SomaScan Assay, based on a study of 2,050 samples across 22 plates. Their presentation includes a robust discussion of the effects of normalization and the low coefficients of variation they observed. Click below to watch their presentation, and read their published research here.

Julián Candia, PhD
Staff Scientist
Longitudinal Studies Section
Translational Gerontology Branch
National Institute on Aging
National Institutes of Health

Keenan Walker, PhD
Investigator, National Institute on
Aging Intramural Research Program
Chief, Multimodal Imaging of
Neurodegenerative Disease (MIND) unit
National Institutes of Health