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(Arteriosclerosis, Thrombosis, and Vascular Biology. 2006;26:2574.)
© 2006 American Heart Association, Inc.

Letters to the Editor

Assessment of a Serum Assay for Quantification of Abdominal Aortic Calcification

Paula Clancy; Lisa Oliver; Rumal Jayalath; Petra Buttner; Jonathan Golledge

From the Vascular Biology Unit (P.C., L.O., R.J., J.G.), School of Medicine, James Cook University, and the School of Public Health and Tropical Medicine (P.B.), James Cook University, Townsville, Australia.

Correspondence to Professor Jonathan Golledge, the Vascular Biology Unit, School of Medicine, James Cook University, Townsville, Qld, 4811, Australia. E-mail jonathan.golledge@jcu.edu.au

Key Words: aortic calcification • osteoprotegerin • osteopontin • sensitivity • specificity

An extract of the first 250 words of the full text is provided, because this article has no abstract.

Intimal vascular calcification is an important marker of atherosclerosis, and its severity is an independent risk factor for cardiovascular events.¹ Measurement of coronary or aortic calcification requires CT-based imaging and elaborate data analysis to ensure accuracy.² A blood assay which could quantify the severity of vascular calcification would be less expensive, avoid exposure to radiation, and be more accessible than present imaging based methods. Osteoprotegerin (OPG) and osteopontin (OPN) are present in human serum and have been implicated in vascular calcification.^3,4 In this prospective study we assessed the value of a number of serum assays for OPG and OPN in determining abdominal aortic calcification. Firstly, we investigated the assay characteristics and reproducibility of 5 ELISAs using a subset of patients. Based on the findings of these assessments, we selected 3 assays for full evaluation in the entire cohort.

Methods

One hundred and nine patients with peripheral vascular disease had fasting serum obtained the morning before measurement of infrarenal abdominal aortic calcification. We assessed a variety of different commercial ELISAs (details are given in the supplemental Methods, available online at http://atvb.ahajournals.org).

Results

Assessment of Assay Characteristics
We identified a large number of commercial ELISAs for OPG with varying reported assay characteristics (see supplemental Methods). We initially compared the OPG ELISAs in terms of recognized assay requirements.⁵ The calibration curves and linearity of the assays were excellent (supplemental Table I). Concordance correlation coefficients for intra- and inter-assay reproducibility were good but most reproducible for the DuoSet assay (supplemental Table II). Each OPG assay uses a different form of . . . [Full Text of this Article]

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