Assay validation for left-censored data.

Journal Article

In laboratory validation studies, it is often important to assess agreement between two assays, based on different techniques. Oftentimes, both assays have lower limits of detection and thus measurements are left censored. For example, in studies of Human Immunodeficiency Virus (HIV), the branched DNA (bDNA) assay was developed to quantify HIV-1 RNA concentrations in plasma. Validation of newer assays, such as the RT-PCR (reverse transcriptase polymerase chain reaction) involves assessing agreement of measurements obtained using the two techniques. Both bDNA and RT-PCR assays have lower limits of detection and thus new statistical methods are needed for assessing agreement between two left-censored variables. In this paper, we present maximum likelihood and generalized estimating equations approaches to evaluate agreement between two assays that are subject to lower limits of detection. The concordance correlation coefficient is used as an agreement index. The methodology is illustrated using HIV RNA assay data collected as part of a long-term HIV cohort study.

Full Text

Duke Authors

Cited Authors

  • Barnhart, HX; Song, J; Lyles, RH

Published Date

  • November 15, 2005

Published In

Volume / Issue

  • 24 / 21

Start / End Page

  • 3347 - 3360

PubMed ID

  • 15977288

Pubmed Central ID

  • 15977288

International Standard Serial Number (ISSN)

  • 0277-6715

Digital Object Identifier (DOI)

  • 10.1002/sim.2225


  • eng

Conference Location

  • England