B-024 Validation of an open-channel assay for measuring serum total bile acid (TBA) using the Cobas® Pro analyzer
Bibliographic record
Abstract
Abstract Background Blood total bile acids (TBA) levels are routinely used for identifying and monitoring intrahepatic cholestasis of pregnancy (ICP). ICP is characterized by disrupted biliary flow causing bile acids to accumulate in circulation which can have consequences on both maternal and fetal outcomes. As such, TBA levels are crucial for appropriate management of patients with ICP and timely results are of particular importance at our institution with a focus on high-risk pregnancy patients. This study aimed to validate an open-channel assay for blood TBA on the cobas® c 503 analyzer following Clinical Laboratory Standards Institute (CLSI) recommendations. Methods The analytical performance of a TBA open-channel assay (Aviva Systems Biology) on the cobas® c 503 analyzer was assessed. Assay parameters were established based on Roche recommendations for converting cobas® c 502 – where TBA was previously being tested on – open-channel parameters to the c 503 analyzer. The validation consisted of precision, correlation, linearity, and dilutional recovery studies using a total allowable error of 10%. The data were visualized using Microsoft Excel and analyzed according to CLSI recommendations. Results Total imprecision of the assay was <2% across both manufacturer quality control materials. Correlation with patient samples (n = 40) against the c502 TBA assay was excellent (R2 = 0.9969) across a concentration range of 1 – 108 µmol/L.The assay demonstrated excellent linearity across the manufacturer stated analytical measurement range (1 – 100 µmol/L) and we were able to extend the measuring range up to 500 µmol/L through verifying acceptable recovery for 1:5 on-board dilutions. Conclusion Using a conversion system to migrate assay parameters from the cobas® c502 to c503 analyzer, we established a TBA assay that demonstrated excellent analytical performance with respect to precision, correlation, linearity, and dilutional recovery.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.016 | 0.016 |
| Meta-epidemiology (narrow) | 0.002 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.003 | 0.002 |
| Science and technology studies | 0.001 | 0.002 |
| Scholarly communication | 0.003 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.003 | 0.001 |
| Insufficient payload (model declined to judge) | 0.005 | 0.006 |
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".