Stability of Novel Plasma Markers Associated with Cardiovascular Disease: Processing within 36 Hours of Specimen Collection

Plasma markers are ideally measured prospectively because marker concentrations may change after diagnosis with disease. In many large prospective studies, such as the Nurses’ Health Study (1) and Health Professionals Follow-up Study (2), blood samples are collected, placed on ice, and mailed back to the central laboratory for processing via overnight or next-day mail service. Because economic constraints typically lead researchers to collect only one sample per study participant (3)(4), it is important to determine the time frame within which markers remain stable and to optimize the methods for handling and processing the sample. Although many studies have examined marker stability after long-term storage, few studies have assessed the impact of transport conditions on whole blood not immediately processed.We selected a series of lipid and novel inflammatory markers whose concentrations have been shown or have been suspected to influence the risk of cardiovascular disease: C-reactive protein (CRP), fibrinogen, lipoprotein (a) [Lp(a)], apolipoprotein B (apoB), intracellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), p-selectin, von Willebrand factor (vWf), oxidized LDL (oxLDL), anti-cardiolipin antibodies (aCLAbs), tumor necrosis factor receptors I and II (TNF-RI and TNF-RII), and matrix metalloproteinase-1 (MMP-1) (5)(6)(7)(8)(9)(10)(11)(12)(13). The purpose of this study was to evaluate the stability of selected novel markers of cardiovascular disease under time and temperature conditions that simulated sample transport by mail for up to 36 h before processing.We included 17 premenopausal women, 25–45 years of age, who had responded to a recruitment advertisement. Blood samples were collected from each woman into three 15-mL Vacutainers containing sodium heparin and placed on ice until processing. The time to processing was defined as the time from when the samples were first placed on ice until they were …