This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Salimnia, H. Articles by Fairfax, M. R. Search for Related Content PubMed PubMed Citation Articles by Salimnia, H. Articles by Fairfax, M. R.

Discordance between Viral Loads Determined by Roche COBAS AMPLICOR Human Immunodeficiency Virus Type 1 Monitor (Version 1.5) Standard and Ultrasensitive Assays Caused by Freezing Patient Plasma in Centrifuged Becton-Dickinson Vacutainer Brand Plasma Preparation Tubes

Department of Pathology and DMC University Laboratories,¹ Division of Allergy, Immunology and Rheumatology, Department of Pediatrics,² Division of Infectious Diseases, Department of Medicine, Wayne State University School of Medicine, 540 E. Canfield, Detroit, Michigan 48201³

Received 11 March 2005/ Returned for modification 25 April 2005/ Accepted 25 May 2005

The Roche COBAS AMPLICOR human immunodeficiency virus type 1 (HIV-1) Monitor (version 1.5) standard and ultrasensitive viral load assays often gave discordant results, with viral loads from the standard assay exceeding those from the ultrasensitive assay by more than 0.5 log₁₀ for approximately 20% of specimens received. We began studies to determine the extent, magnitude, and reproducibility of the discordance between the assays and to discover and eliminate the cause of this discordance. Until then, we revised our standard operating procedure to include both standard and ultrasensitive testing on all specimens submitted for viral load determinations. Discordant results usually recurred on retesting. They were most prevalent for specimens with ultrasensitive viral loads of <1,000 and rare for specimens with viral loads of >10,000. Often, standard assay results exceeded those of the ultrasensitive assay by 50- to 100-fold. At higher viral loads, the difference between the standard and ultrasensitive assays persisted, but the percent difference was smaller and rarely caused discordance. The proportion of discordant results was significantly higher in specimens from pediatric patients than in specimens from adults. The ultrasensitive viral load determinations generally agreed with the results of the B-DNA (Bayer) viral load assays. If the plasma was transferred from the centrifuged plasma preparation tubes before freezing, standard and ultrasensitive results were concordant with each other and with values determined on plasma from lavender-topped EDTA tubes.

This article has been cited by other articles:

• Marinovich, A., Narlieva, M., Bashir, M., Zingman, B. S., Fox, A. (2006). False-Positive Result from a Bayer Versant Human Immunodeficiency Virus Type 1 Branched-DNA Viral Load Assay, with a Possible Role for Light Leakage after Inadequate Maintenance of the Analyzer. J. Clin. Microbiol. 44: 4288-4289 [Full Text]