Quantitative Evaluation of the Real-World Harmonization Status of Laboratory Test Items Using External Quality Assessment Data.

Background: In recent decades, the analytical quality of clinical laboratory results has substantially increased because of collaborative efforts. To effectively utilize laboratory results in applications, such as machine learning through big data, understanding the level of harmonization for each test would be beneficial. We aimed to develop a quantitative harmonization index that reflects the harmonization status of real-world laboratory tests. Methods: We collected 2021-2022 external quality assessment (EQA) results for eight tests (HbA1c, creatinine, total cholesterol, HDL-cholesterol, triglyceride, alpha-fetoprotein [AFP], carcinoembryonic antigen [CEA], and prostate-specific antigen [PSA]). This EQA was conducted by the Korean Association of External Quality Assessment Service, using commutable materials. The total analytical error of each test was determined according to the bias% and CV% within peer groups. The values were divided by the total allowable error from biological variation (minimum, desirable, and optimal) to establish a real-world harmonization index (RWHI) at each level (minimum, desirable, and optimal). Good harmonization was arbitrarily defined as an RWHI value ≤ 1 for the three levels. Results: Total cholesterol, triglyceride, and CEA had an optimal RWHI of ≤ 1, indicating an optimal harmonization level. Tests with a desirable harmonization level included HDL-cholesterol, AFP, and PSA. Creatinine had a minimum harmonization level, and HbA1c did not reach the minimum harmonization level. Conclusions: We developed a quantitative RWHI using regional EQA data. This index may help reflect the actual harmonization level of laboratory tests in the field.

A New Strategy for Evaluating the Quality of Laboratory Results for Big Data Research: Using External Quality Assessment Survey Data (2010-2020).

Background: To ensure valid results of big data research in the medical field, the input laboratory results need to be of high quality. We aimed to establish a strategy for evaluating the quality of laboratory results suitable for big data research. Methods: We used Korean Association of External Quality Assessment Service (KEQAS) data to retrospectively review multicenter data. Seven measurands were analyzed using commutable materials: HbA1c, creatinine (Cr), total cholesterol (TC), triglyceride (TG), alpha-fetoprotein (AFP), prostate-specific antigen (PSA), and cardiac troponin I (cTnI). These were classified into three groups based on their standardization or harmonization status. HbA1c, Cr, TC, TG, and AFP were analyzed with respect to peer group values. PSA and cTnI were analyzed in separate peer groups according to the calibrator type and manufacturer, respectively. The acceptance rate and absolute percentage bias at the medical decision level were calculated based on biological variation criteria. Results: The acceptance rate (22.5%-100%) varied greatly among the test items, and the mean percentage biases were 0.6%-5.6%, 1.0%-9.6%, and 1.6%-11.3% for all items that satisfied optimum, desirable, and minimum criteria, respectively. Conclusions: The acceptance rate of participants and their external quality assessment (EQA) results exhibited statistically significant differences according to the quality grade for each criterion. Even when they passed the EQA standards, the test results did not guarantee the quality requirements for big data. We suggest that the KEQAS classification can serve as a guide for building big data.

Recent Trends in Creatinine Assays in Korea: Long-Term Accuracy-Based Proficiency Testing Survey Data by the Korean Association of External Quality Assessment Service (2011-2019).

BACKGROUND: Accurate serum creatinine (Cr) concentration measurement is essential for evaluating kidney function. In 2011, the Korean Association of External Quality Assessment Service (KEQAS) launched an accuracy-based Cr proficiency testing (ABCr PT) survey. We analyzed long-term data of the KEQAS ABCr PT survey collected between 2011 and 2019 to assess recent trends in Cr assays in Korea. METHODS: The ABCr PT survey including three commutable fresh-frozen serum samples was performed twice a year. The target Cr concentration was assigned using isotope-dilution mass spectrometry. We analyzed data obtained from the participating laboratories, calculated the yearly bias, and evaluated bias trends for the major reagents and instruments. Outliers were excluded from all analysis. RESULTS: The mean percentage bias based on the total data of all participating laboratories was 10.8% in the 2011-A survey and 0.2% in 2019-B survey. Bias for the major reagents and instruments differed depending on the manufacturer. Enzymatic assays generally showed desirable bias ranging from -3.9% to 3.2% at all Cr concentrations and lower interlaboratory variability than non-enzymatic assays (enzymatic vs. non-enzymatic, 3.3%-7.2% vs. 6.3%-9.1%). CONCLUSIONS: Although the mean percentage bias of Cr assays tends to decrease over time, it is necessary to continuously strive to improve Cr assay accuracy, especially at low concentrations.

Accuracy Assessment of Five Equations Used for Estimating the Glomerular Filtration Rate in Korean Adults.

BACKGROUND: We aimed to assess the performance of the five creatinine-based equations commonly used for estimates of the glomerular filtration rate (eGFR), namely, the creatinine-based Chronic Kidney Disease Epidemiology Collaboration (CKD-EPIcr), Asian CKD-EPI, revised Lund-Malmö (revised LM), full age spectrum (FAS), and Korean FAS equations, in the Korean population. METHODS: A total of 1,312 patients, aged 20 yr and above who underwent 5¹Cr-EDTA GFR measurements (mGFR), were enrolled. The bias (eGFR-mGFR) and precision (root mean square error [RMSE]) were calculated. The accuracy (P30) of four eGFR equations was compared to that of the CKD-EPIcr equation. P30 was defined as the percentage of patients whose eGFR was within±30% of the mGFR. RESULTS: The mean bias (mL·min⁻¹·1.73 m⁻²) of the five eGFR equation was as follows: CKD-EPIcr, -0.6; Asian CKD-EPI, 2.7; revised LM, -6.5; FAS, -2.5; and Korean FAS, -0.2. The bias of the Asian CKD-EPI, revised LM, and FAS equations showed a significant difference from zero (P<0.001). The RMSE values were as follows: CKD-EPIcr, 15.6; Asian CKD-EPI, 15.6; revised LM, 17.9; FAS, 16.3; and Korean FAS, 15.8. There were no significant differences in the P30 except for the Asian CKD-EPI equation: CKD-EPIcr, 76.6%; Asian CKD-EPI, 74.7%; revised LM, 75.8%; FAS, 76.0%; and Korean FAS, 75.8%. CONCLUSIONS: The CKD-EPIcr and Korean FAS equations showed equivalent analytical and clinical performances in the Korean adult population.

Accuracy Assessment of Three Different Lots of the LABGEO PT Hemoglobin A1c Test Using Reference Materials.

BACKGROUND: Both accurate measurement of HbA1c and minimal reagent lot-to-lot variability are essential for point-of-care HbA1c assays. The accuracy of three different cartridge lots of the Samsung LABGEO PT HbA1c Test was investigated to determine whether the results can be used for follow-up and screening of patients with diabetes. METHODS: The LABGEO PT10 device and three different lots of the LABGEO PT HbA1c Test cartridge were used. Seven levels of reference materials were measured using each cartridge in a duplicate manner for 3 days. The bias, within-laboratory precision, and total error were calculated. The medical decision point analysis was performed. RESULTS: The mean absolute bias, within-laboratory precision, and total error of each cartridge were 3.3%, 2.5%, and 8.1% for Lot1; 1.9%, 2.6%, and 7.1% for Lot2; and 2.7%, 2.8%, and 8.1% for Lot3. The predicted value (95% confidence interval) of each cartridge at an HbA1c of 6.5% was 6.74% (6.66, 6.83) for Lot1, 6.60 (6.51, 6.70) for Lot2, and 6.51 (6.39, 6.63) for Lot3. CONCLUSIONS: Our data suggest that the LABGEO PT HbA1c Test can be used to monitor patients with diabetes and perform diabetes screening when false-positive results are obtained in the doctor's office.

Procalcitonin in the assessment of bacteraemia in emergency department patients: results of a large retrospective study.

BACKGROUND: The aim of this study was to evaluate the use of procalcitonin in the assessment of bacteraemia in patients in the emergency department, both alone and in conjunction with existing inflammatory markers of bacterial infection. METHODS: We enrolled 3305 cases (range 20-90 years) for which we retrospectively compared procalcitonin concentration, blood culture results, body temperature, absolute neutrophil count, and C-reactive protein concentration. The positive predictive value and the negative predictive value of procalcitonin were established at different cut-off concentrations. Receiver operating characteristic curves were plotted, and the areas under the ROC curves calculated, to allow assessment of the diagnostic accuracy of (a) a combination of three existing inflammatory markers of bacterial infection (body temperature, C-reactive protein, absolute neutrophil count), and (b) this combination with procalcitonin. RESULTS: Positive predictive values of procalcitonin using 0.1, 1, 2, and 5 ng/mL as the cut-off values were 21.2, 32.2, 34.2, and 37.0%, respectively. Negative predictive values of procalcitonin using 0.1, 1, 2, and 5 ng/mL as the cut-off values were 95.1, 92.2, 91.1, and 89.0%, respectively. Areas under the curve of three inflammatory markers (absolute neutrophil count, C-reactive protein, and body temperature) combined was 0.879; areas under the curve of these markers combined with procalcitonin was 0.932 (p = 0.018). CONCLUSIONS: When procalcitonin is used as a serum marker for ruling out bacteraemia, a cut-off of 0.1 ng/mL may be used. Procalcitonin improves the diagnostic accuracy of existing markers of bacteraemia.