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. 2019 Nov 20;14(11):e0223597.
doi: 10.1371/journal.pone.0223597. eCollection 2019.

Can visual interpretation of NucliSens graphs reduce the need for repeat viral load testing?

Newten Handireketi  1 , Collins Timire  2   3   4 , Hemant Deepak Shewade  4   5 , Ellen Munemo  2 , Charles Nyagupe  2 , Sandra Chipuka  2 , Lucia Sisya  2 , Hlanai Gumbo  2 , Ezekiel Dhitima  2 , Anthony D Harries  4   6
Affiliations

Can visual interpretation of NucliSens graphs reduce the need for repeat viral load testing?

Newten Handireketi et al. PLoS One. .

Abstract

Background: In Zimbabwe, viral load (VL) testing for people living with HIV on antiretroviral therapy is performed at the National Microbiology Reference Laboratory using a NucliSens machine. Anecdotal evidence has shown that invalid graphs for "Target Not Detectable (TND)" will upon repeat VL testing produce a valid result for virus not detected, therefore removing the need to repeat the test. This needs formal assessment.

Objectives: To determine i) intra- and inter-rater agreement of the visual interpretation of NucliSens graphs (Target Detectable [TD], TND and No Line [NL]) between two laboratory scientists and ii) sensitivity, specificity and predictive values of the NucliSens graphs compared with repeat VL results.

Method: Cross sectional study using secondary data. Two laboratory scientists independently rated graphs one week apart for intra-rater agreement and compared final ratings with each other for inter-rater agreement. Consensus interpretations of graphs were compared with repeat VL results. Kappa coefficients were used to obtain measures of agreement.

Results: There were 562 patients with NucliSens graphs and repeat VL. Kappa scores were: 0.98 (Scientist A); 0.99 (Scientist B); 0.96 (Scientist A versus Scientist B); and 0.65 (NucliSens graphs versus VL). Sensitivity, specificity, positive predictive value and negative predictive value for graphs compared with VL were 71%, 92%, 79% and 89% respectively.

Conclusion: Intra-and inter-rater agreements were almost perfect. The negative predictive value translates to a false negative rate of 11%. If repeat VL testing is not done, the clinical consequences need to be balanced against cost savings and the risks outweigh the benefits.

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Conflict of interest statement

The authors have declared that no competing interests exist.

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