Journal of Applied Laboratory Medicine最新文献

Background: To evaluate diagnostic tests for low prevalence conditions, classification accuracy metrics such as sensitivity, specificity, and positive likelihood ratio (PLR) and negative likelihood ratio (NLR) are advantageous because they are prevalence-independent and thus estimable in studies enriched for the condition. However, classification accuracy goals are often chosen without a clear understanding of whether they are clinically meaningful. Pennello (2021) proposed a risk stratification framework for determining classification accuracy goals. A software application is needed to determine the goals and provide data analysis.

Methods: We introduce DxGoals, a freely available, R-Shiny software application for determining, visualizing, and analyzing classification accuracy goals for diagnostic tests. Given prevalence p for the target condition and specification that a test's positive and negative predictive values PPVand NPV=1-cNPV should satisfy PPV>PPV* and cNPV

Results: We illustrate DxGoals on tests for penicillin allergy, ovarian cancer, and cervical cancer. The inputs cNPV*,p, and PPV* were informed by clinical management guidelines.

Conclusions: DxGoals facilitates determination, visualization, and analysis of clinically meaningful standalone and comparative classification accuracy goals. It is a potentially useful tool for diagnostic test evaluation.

Background: The objective of this study was to compare The Binding Site's Freelite on Optilite and Diazyme's Kappa/Lambda free light chains (K/L FLC) on Abbott Architect c8000 with healthy and renal insufficient populations and to evaluate their respective reference intervals for serum free light chains (sFLCs).

Methods: Two hundred sixty serum samples were measured for creatinine and sFLCs by both assays and a subset by immunofixation electrophoresis. Verification of manufacturer-defined reference intervals was assessed.

Results: Kappa free light chains (KFLC) showed excellent correlation of 0.998 R2 with a slope of 0.73. For Lambda free light chains (LFLC), an acceptable correlation of 0.953 R2 was found with a slope of 1.50 as well as a skewness-based difference with a -12.70 intercept. Healthy estimated glomerular filtration rate (eGFR) ≥60 reference interval verification of central 95% could not be confirmed for either Freelite or Diazyme although LFLC was much closer than KFLC for both assays with Freelite KFLC recovering only 37% of values within reference interval claims. The K/L FLC ratio did not meet 100% claim for both Freelite (91%) and Diazyme (95%) among those with eGFR ≥60. Samples with eGFR ≤59 had increasingly higher levels of KFLC and LFLC for both assays. When comparing worsening eGFR status, Freelite recovered increasingly higher ratios while Diazyme recovered increasingly lower ratios.

Conclusions: Healthy reference intervals could not be verified for either Freelite or Diazyme. Renal reference intervals for Freelite are currently warranted while they are not recommended for Diazyme. The differences between these 2 assays can be minimized by standardization efforts such as recalibration.

Background: The clinical management of chronic myeloid leukemia (CML) patients requires the identification of the type of BCR::ABL1 transcript at diagnosis and the monitoring of its expression and potential tyrosine kinase inhibitor (TKI) resistance mutations during treatment. Detection of resistant mutation requires transcript type-specific amplification of BCR::ABL1 from RNA.

Methods: In this study, a custom RNA-based next-generation sequencing (NGS) assay (Dup-Seq BCR::ABL1) that enables (a) the identification of BCR::ABL1 transcript type and (b) the detection of resistance mutations from common and atypical BCR::ABL1 transcript types was developed and validated. The assay design covers BCR exon 1 to ABL1 exon 10 and employs duplicate PCR amplification for error correction. The custom data analysis pipeline enables breakpoint determination and overlapped mutation calling from duplicates, which minimizes the low-level mutation artifacts.

Results: This study demonstrates that this novel assay achieves high accuracy (positive percent agreement (PPA) for fusion: 98.5%; PPA and negative percent agreement (NPA) for mutation at 97.8% and 100.0%, respectively) and sensitivity (limit of detection (LOD) for mutation detection at 3% from 10 000 copies of BCR::ABL1 input).

Conclusions: The Dup-Seq BCR::ABL1 assay not only allows for the identification of BCR::ABL1 typical and atypical transcript types and accurate and sensitive detection of TKI-resistant mutations but also simplifies molecular testing work flow for the clinical management of CML patients.

Background: Cardiac troponin T (cTnT) is key in diagnosing myocardial infarction (MI) but is also elevated in end-stage renal disease (ESRD) patients. Specific larger cTnT proteoforms were identified for the acute phase of MI, while in serum of ESRD patients solely small cTnT fragments were found. However, others allocated this to a pre-analytic effect due to abundant thrombin generation in serum. Therefore, we investigated the effect of various anticoagulation methods on cTnT composition and concentration and compared the cTnT composition of MI and ESRD patients.

Methods: The agreement of cTnT concentrations between simultaneously collected serum, lithium-heparin (LH) plasma, and ethylenediaminetetraacetic acid (EDTA) plasma was studied using the high-sensitivity (hs-)cTnT immunoassay. cTnT proteoform composition was investigated in a standardized time-dependent manner through spike experiments and in simultaneously collected blood matrixes of MI and ESRD patients.

Results: Excellent hs-cTnT concentration agreements were observed across all blood matrixes (slopes > 0.98; 95% CI, 0.96-1.04). Time-dependent degradation (40 kDa intact:29 kDa fragment:15 to 18 kDa fragments) was found in LH plasma and EDTA plasma, and serum in ratios (%) of 90:10:0, 0:5:95, and 0:0:100, respectively (48 h after blood collection). Moreover, gel filtration chromatography (GFC) profiles illustrated mainly larger cTnT proteoforms in MI patients, while in ESRD patients mainly 15 to 18 kDa fragments were found for all matrices.

Conclusions: The extent of cTnT degradation in vitro is dependent on the (anti)coagulation method, without impacting hs-cTnT concentrations. Furthermore, mainly larger cTnT proteoforms were present in MI patients, while in ESRD patients mainly small 15 to 18 kDa cTnT fragments were found. These insights are essential when developing a novel hs-cTnT assay targeting larger cTnT proteoforms.

Background: Mild traumatic brain injury (mTBI) is defined as a Glascow Coma Score of between 13 and 15. The diagnosis and rule out of individuals suffering from mTBI on an acute basis is imperfect and involves subjective measures. Serum biomarkers that exhibit narrow within-individual biological variation can be used for the early rule-out of mTBI, when baseline levels are compared during health.

Methods: This is a descriptive study that applies published biological variation data of serum mTBI biomarkers for early rule out of sports-related injury.

Results: Laboratory tests such as glial fibrillary acidic protein, fatty acid binding protein 7, and phosphorylated protein enriched in astrocytes have low within-individual variances and are potential candidates. Aldolase C also rises early in blood but the biological variation is of this marker is currently unknown.

Conclusions: The use of blood-based biomarkers, measured in real time using point-of-care testing devices when compared to a pre-competition baseline instead of a population-based reference interval, can provide early rule out of mTBI, and possibly enable on-field evaluations and a medical decision for a return to competition.

Background: A dual filtration-based method for determination of serum labile bound copper (LBC) and LBC fraction (LBC/total copper) was developed. Reduced total copper, elevated LBC, and elevated LBC fraction have been reported in Wilson disease (WD).

Methods: To evaluate the diagnostic performance of these markers, samples were obtained from 21 WD treatment-naïve (WD-TN, no WD treatment or <28 days of treatment) patients, 46 WD standard-of-care-treated (WD-SOC) patients, along with 246 patients representing other potential disorders of copper status. These were then compared to 213 reference interval population patients.

Results: Receiver operating characteristic curves for the reference population vs WD-TN yielded areas under the curve for total copper, LBC, and LBC fraction, of 0.99, 0.81, and 0.98, respectively. Using Youden cutoffs, sensitivity/specificity for WD-TN was 95%/97% for total copper, 71%/85% for LBC, and 95%/94% for LBC fraction. LBC values, but not total copper and LBC fraction, differed substantially between WD-TN and WD-SOC cohorts.We propose a dual model wherein total copper and LBC fraction results must agree to be classified as a "positive" or "negative" result for WD. This correctly classified 19/21 WD-TN patients as positive, and 194/213 reference interval patients as negative. The remaining "indeterminate" patients (representing approximately 9% of the reference and the WD-TN populations) exhibited conflicting total copper and LBC fraction results. When indeterminate results are excluded, this model exhibited apparent 100% sensitivity/specificity.

Conclusions: Agreement of total serum copper and LBC fraction classification may constitute an effective "rule-in" and "rule-out" assessment for WD-TN patients.

Background: A new Rapid Drug Test Device (RDTD) is available for analysis of urine fentanyl. With the rise in fentanyl abuse in the United States, we evaluated the analytical performance of the RDTD test strip compared to mass spectrometry and 2 urine fentanyl immunoassays.

Methods: Leftover, deidentified urine samples collected from inpatients and outpatients from our psychiatric hospital and other clinics were frozen at <-70°C, thawed at room temperature, and centrifuged. Aliquots were tested with the RDTD (CLIA Waived, Inc.) test strips and 2 urine fentanyl immunoassays: the ARK Fentanyl II assay (ARK Diagnostics Inc.) and the Immunalysis SEFRIA Fentanyl assay (Immunalysis Corporation). Both assays were conducted on the Abbott Alinity c chemistry analyzer (Abbott Laboratories). Mass spectrometry analysis was performed at ARUP Laboratories. All assays had a 1 ng/mL positive cutoff.

Results: A total of 142 urine samples included 70 positive and 72 negative samples. The RDTD strips had lower sensitivity (84.3%) and efficiency (85.9%) and showed a specificity of 87.5% compared to the other assays. The ARK Fentanyl II assay showed identical sensitivity (95.7%) to the Immunalysis SEFRIA Fentanyl assay but had higher specificity (94.4% vs 81.9%) and overall efficiency (95.1% vs 88.7%).

Conclusions: Differences were noted in the number of false negatives and positives among the assays. The RDTD demonstrated acceptable performance in detecting urine fentanyl in our patient population and would provide faster test results at point-of-care testing sites in our healthcare enterprise.