The robustness of the Roche 2nd generation homogenous HDL cholesterol (PEGME) method:: Assessment of the effect of serum sample storage for up to 8 years at -80°C

Background: Low HDL-cholesterol (HDL-C) is a strong and independent cardiovascular risk factor. Clinical trials often necessitate storage of samples before assay. Results are lacking for longer-term storage with quantification of HDL-C using different methods before and after storage. Methods: Serum samples (n=2936) from the Collaborative Atorvastatin Diabetes Study in which HDL-C had been determined on 'fresh' samples using the MnCl2/heparin method before freezing and storage for up to 8 years at -80 degrees C were thawed and HDL-C was determined using the Roche direct method. We participated in the Riqas QC programme and results obtained for the control serum samples using a CDC-approved method were used to generate a regression equation and thus to adjust both original results, obtained after precipitation and also to align the direct HDL-C results. Results: CDC-aligned HDL-C results for stored samples were lower than CDC-aligned HDL-C results before storage (mean [S.E.M.]: 1.41 [0.01] vs. 1.43 [0.01] mmol/L; P < 0.0001, n=2936). Although results after storage tended to be lower, there was no significant time-dependent change in the ratio of original to stored results for HDL-C. Conclusions: The study establishes that the Roche 2nd generation PEGME method is robust and eminently suitable for determinations of HDL-C in stored serum samples. (c) 2007 Elsevier B.V. All rights reserved.