The contribution of assay variation and biological variation to the total variability of plasma HIV-1 RNA measurements

• Published in: AIDS (London) Vol. 13; no. 16; pp. 2269 - 2279
• Main Authors: Brambilla, Donald, Reichelderfer, Patricia S., Bremer, James W., Shapiro, David E., Hershow, Ronald C., Katzenstein, David A., Hammer, Scott M., Jackson, Brooks, Collier, Ann C., Sperling, Rhoda S., Fowler, Mary Glenn, Coombs, Robert W.
• Format: Journal Article
• Language: English
• Published: Hagerstown, MD Lippincott Williams & Wilkins 12.11.1999
• Subjects: batch testing; Biological and medical sciences; biological variation; Human immunodeficiency virus 1; Human viral diseases; Infectious diseases; Medical sciences; real-time testing; Viral diseases; Viral diseases of the lymphoid tissue and the blood. Aids; viral load; Human; Measurement; Immunopathology; RNA; HIV-1 virus; Variability; Retroviridae; AIDS; Real time; Immune deficiency; Lentivirus; Blood plasma; Infection; Virus; Viral disease; Risk factor; Human immunodeficiency virus; Measurement method; Viral load; Comparative study
• ISSN: 0269-9370
• DOI: 10.1097/00002030-199911120-00009

Objectives: To assess the specific contributions of assay variation and biological variation to the total variation of plasma HIV-1 RNA measured by the Roche Monitor assay and the extent to which batch assays reduced both assay variability and total variability compared with real-time determinations. Design: A retrospective analysis of data obtained from three trials conducted by the Adult and Pediatric AIDS Clinical Trials Groups (ATCG), the Women and Infants Transmission Study (WITS) and the NIAID-sponsored Virology Quality Assurance Program. Methods: Within-subject variation was assessed from stored, serially collected plasma samples from 663 subjects enrolled in the ACTG and WITS studies. Interassay and intra-assay variation were estimated from two of the clinical trials and 22 laboratories that participated in a quality assurance program and were used to estimate the effect of real-time testing on total variation. Results: The total variation (standard deviation) from a random effects model was 0.26 log sub(10) RNA copies/ml. The estimated interassay variation was 0.08 log sub(10) and intra-assay variation was 0.12 log sub(10) RNA copies/ml. Biological variation accounted for 56-80% of total variation. The effect of real-time testing compared with batch testing was minimal. Conclusion: Our estimates of total within-subject HIV-1 RNA variation support the current recommendation to obtain at least two specimens, preferably obtained less than 2 weeks apart, for viral RNA measurement before starting therapy. The major contribution of biological variation to the total variation supports the use of real-time HIV-1 RNA assays, provided that consistent specimen collection procedures are followed and acceptable assay proficiency is maintained.