Poor Agreement between 2 Assays for Measuring Low Levels of HIV‐1 Viral Load
Bibliographic record
Abstract
To the Editor—The current goal of antiretroviral therapy is to sustain the suppression of plasma human immunodeficiency virus type 1 (HIV-1) RNA to <50 copies/mL [1]. Such suppression prevents the emergence of resistance, enables immune reconstitution, prevents disease progression, and prolongs survival [1]. A confirmed detectable plasma HIV-1 RNA level of >50 copies/mL in a patient with a previously, consistently suppressed level of <50 copies/mL while on antiretroviral therapy is a signal of possible virologic failure, requiring further evaluation to assess patient adherence to therapy and the need for a regimen modification [1]. Prompt action in this setting is deemed important to prevent the evolution of HIV resistance, which may narrow effective future treatment options and compromise clinical outcome [2, 3]. Most of the data supporting these recommendations have been generated using an ultrasensitive assay (ie, the Roche COBAS HIV-1 Ampliprep Amplicor Monitor, version 1.5; Roche Diagnostics Systems) (hereafter referred to as the Amplicor assay). In early 2008, the COBAS Ampliprep TaqMan HIV-1 assay (Roche Diagnostics Systems) (hereafter referred to as the TaqMan assay) was introduced as an alternative. Compared with the Amplicor assay, the TaqMan assay is technically simpler and has a wider dynamic range. Although the Amplicor and TaqMan assays perform comparably over their respective overall dynamic ranges, there is an increasing concern that these assays may have poor agreement around the crucial clinical threshold of 50 copies/mL.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.044 | 0.166 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.002 | 0.001 |
| Bibliometrics | 0.002 | 0.001 |
| Science and technology studies | 0.001 | 0.002 |
| Scholarly communication | 0.003 | 0.002 |
| Open science | 0.002 | 0.002 |
| Research integrity | 0.009 | 0.008 |
| Insufficient payload (model declined to judge) | 0.002 | 0.004 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".