Schemes and Performance Evaluation Criteria of Korean Association of External Quality Assessment (KEQAS) for Improving Laboratory Testing

External quality assessment (EQA) is important for evaluating clinical laboratories and enhancing their testing quality. EQA schemes are variable; thus, it is crucial that the EQA organizers share their experiences to continuously improve the EQA scheme. The Korean Association of External Quality Assessment Service (KEQAS) has been the leading, authorized EQA institute for the standardization and quality management of laboratory testing in Korean medical institutions since 1976. The EQA scheme underwent a major change in 2016, and the number of EQA programs increased significantly since then. The key changes implemented in EQA scheme include a fully computerized assessment to accelerate feedback and unification of the testing and reporting methods. We provide an overview of the EQA schemes and performance evaluation criteria of the KEQAS and suggest directions for achieving the global harmonization of EQA.

Standardization Status of Total Cholesterol Concentration Measurement: Analysis of Korean External Quality Assessment Data

Background@#Total cholesterol concentration measurement is important in the diagnosis of dyslipidemia and evaluation of cardiovascular disease risk factors. Measurement reliability for obtaining an accurate total cholesterol concentration requires procedure standardization. We evaluated the standardization status for total cholesterol concentration measurement through Korean external quality assessment (EQA) data analysis. @*Methods@#This study involved 1,670 laboratories that participated in the EQA of total cholesterol concentration measurements in 2019 for 32 products from different manufacturers. The target concentrations of three quality control (QC) materials (samples A, B, and C) were measured using the reference method and compared with EQA data. The performance criteria for total cholesterol concentration measurement were based on the National Cholesterol Education Program guidelines, with ± 3% inaccuracy. @*Results@#The target values and inaccuracies of the QC material based on the reference method measurements were 254.65 ± 7.64, 108.30 ± 3.25, and 256.29 ± 7.69 mg/dL (6.59 ± 0.20, 2.80 ± 0.08, and 6.63 ± 0.20 mmol/L) for samples A, B, and C, respectively.The performance criteria were not met in 42.7% laboratories for sample A, 68.4% of laboratories for sample B, and 38.0% laboratories for sample C. @*Conclusions@#Despite significant efforts to accurately measure total cholesterol concentrations, further actions are needed for measurement standardization. Manufacturers reporting values that differ from target values should check calibrator traceability; additional efforts to accurately measure total cholesterol concentrations are required for laboratories that use products from these manufacturers.

Recent Trends in Creatinine Assays in Korea: LongTerm 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.

Development of an Operational Plan for the Liquid Biopsy External Quality Assessment Program in Korea

Background@#Liquid biopsy is a useful assay for the diagnosis, treatment, and prognosis prediction of solid tumors and its clinical application is expanding. Therefore, the need for developing an External Quality Assessment (EQA) protocol for liquid biopsy is increasing. In this study, we developed and implemented the liquid biopsy EQA program for the epidermal growth factor receptor mutation. @*Methods@#We validated the feasibility of the protocol using citrate instead of ethylenediaminetetraacetic acid (EDTA). Additionally, we analyzed the homogeneity and stability of the aliquoted quality control (QC) materials. Mutation-positive QC material with four mutations (exon 19 deletion, L858R, T790M, and exon 20 insertion) was used to make two types of QC materials (low and high) and the wild type material was used for the negative controls. If the EQA results showed consensus in more than 80% of the participating laboratories, the results were reported as acceptable or unacceptable. If not, we reported the results as not graded. @*Results@#Citrate showed equivalent performance to EDTA. Highly mutated QC material and mutation-negative QC material passed the homogeneity and stability test, but low-level mutant specimens showed inconsistent results. In total, 11 laboratories participated, and all of them reported consistent results except for low-grade mutant samples. Thus, the evaluation results were acceptable except for low mutation QC material. @*Conclusions@#The applicability of liquid biopsy is expanding. To obtain accurate test results, EQA is indispensable. Here, QC materials for liquid biopsy EQA were produced, distributed, and had its results analyzed. This study could be the foundation for further development of liquid biopsy EQA.

Identification of a Novel Splice Variant (c.423-8A>G) of APC by RNA Sequencing

No abstract available.

Essential Elements for Establishing Clinical Next-generation Sequencing Testing

Over the past decade, next-generation sequencing (NGS) has evolved at an astonishing pace and has revolutionized clinical medicine as well as genomics research. The rapid advancements in NGS technologies have been accompanied by accumulating evidence of the analytical and clinical validity, and clinical utility of NGS. NGS is used worldwide. This review provides medical technicians and laboratory physicians with the essential elements for establishing clinical NGS testing. Here the authors briefly describe the advantages and drawbacks of currently available NGS platforms, potential sources of error in NGS workflow, and reference materials.

Performance Evaluation of the Stat Profile pHOx Ultra Blood Gas Analyzer

The objective of this study was to evaluate the analytical performance of the Stat Profile pHOx Ultra Blood Gas Analyzer (Nova Biomedical, USA), a new blood gas/chemistry analyser, including its precision and linearity, comparison studies, and the carry-over effect of commercial reagents and patient specimens. We assessed all the results on the basis of the Clinical and Laboratory Standards Institute guidelines. The following parameters were assessed: pH, partial pressure of carbon dioxide, partial pressure of oxygen, ionized calcium, ionized magnesium (iMg), and lactate concentration The total imprecision had a coefficient of variation of 0.0%–1.8%, and the linear measurement ranges for each parameter were all acceptable. In comparison with the Nova Critical Care Xpress Analyzer (Nova Biomedical, USA), the results indicated a good agreement, except for iMg. All carry-over ranges were between −0.5% and −1.4%. The Stat Profile pHOx Ultra Blood Gas Analyzer showed good analytical performance in terms of precision, linearity, comparison studies, and carry-over effect. The Stat Profile pHOx Ultra Blood Gas Analyzer can provide reliable measurements across a clinically relevant range and has potential use in laboratory tests.

Effect of Accreditation on the Accuracy of Diagnostic Hematologic Tests: Standard Deviation Index Analysis

No abstract available.

Budget Impact of the Accreditation Program for Clinical Laboratories on Colorectal Cancer Screening via Fecal Immunochemical Testing: Results from the National Cancer Screening Program in Korea

BACKGROUND: False-positive fecal immunochemical test (FIT) results in the National Cancer Screening Program (NCSP) for colorectal cancer may lead to unnecessary procedures, such as colonoscopies, increasing the medical costs. We estimated reductions in the cost of National Health Insurance according to the accreditation status of screening facilities participating in the NCSP for colorectal cancer. METHODS: We used data collected between 2007 and 2010 from NCSP and the Korea Central Cancer Registry to identify patients with colorectal cancer. We also ascertained the history of the accreditation of each facility by the Korean Laboratory Accreditation Program (KLAP). Budget impact was defined as a reduction in medical costs achieved when the false-positive rate of the non-accredited facilities decreased relative to that of the accredited facilities. RESULTS: A total of 3,285 screening facilities participated in the NCSP. Of these, 196 were accredited by the KLAP. The false-positive rate of the accredited facilities was 2.47%, and that of the non-accredited facilities was 6.83%. Medical costs were estimated to be reduced by approximately 19 million US dollars (USD), and the cost of detecting one case of colorectal cancer was estimated to decrease from 9,212 USD to 7,332 USD if the false-positive rate of non-accredited facilities were decreased to that of the accredited facilities. Clinics were estimated to have the largest associated cost reduction. CONCLUSIONS: Quality assurance in clinical laboratories could lower false-positive rates and prevent the use of unnecessary procedures, ensuring patient safety and increasing the cost-effectiveness of FIT screening in the NCSP for colorectal cancer.

Evaluation of the 1B Equation to Estimate Glomerular Filtration Rate in Pediatric Patients with Cancer

The 1B equation is recommended for calculating the glomerular filtration rate (GFR) in children. Since few reports have evaluated the performance of the 1B equation, we investigated the performance of estimated GFR (eGFR) equations with the blood urea nitrogen (BUN) variable for pediatric cancer patients. In total, 203 children with cancer who underwent measured GFR (mGFR) assessment were enrolled. The median (range) mGFR and eGFR calculated using the updated Schwartz equation were 118 (43–241) and 135 (34–257) mL/min/1.73 m², respectively. The bias, precision (root mean square error [RMSE]), and accuracy (P30, mGFR±30%) of three eGFR equations including updated Schwartz, 1B, and full age spectrum (FAS) were compared. The median bias (mL/min/1.73 m²) was: updated Schwartz, 8.5; 1B, −9.0; and FAS, 4.2. The biases for all three eGFR equations were significantly different from zero. The P30 was: updated Schwartz, 63.5%; 1B, 66.0%; and FAS, 66.0%. The RMSE was the lowest for the 1B equation (40.4), followed by FAS (42.3), and updated Schwartz (45.5). The median eGFR/mGFR ratio for the eGFR equations decreased with age and reduced kidney functions (i.e., increased creatinine and BUN concentrations). The bias may be further reduced by using the average from two equations, such as the updated Schwartz and 1B, or FAS equation, rather than using the updated Schwartz or 1B equation alone. The use of the 1B equation may underestimate the GFR. Using creatinine and BUN variables in the eGFR equation may yield a more accurate estimate of the GFR in pediatric cancer patients.

Reducing the Reporting Time by Improving Laboratory Processing for Inpatient Routine Chemistry Tests

BACKGROUND: The returning time of inpatient specimen analysis is usually slow because phlebotomists deliver all the collected specimens at the end of their work cycle. In addition, manual specimen reception further delays the reporting time and imposes a heavy workload on the technical staff, thus compromising effectiveness. Therefore, we have created an automated specimen reception system to tackle testing delays and enhance the efficiency and quality of specimen collection and handling. METHODS: In May 2015, the pre-analytical processing of inpatient samples was renovated. We automated the specimen reception in parallel with barcode printing and introduced pneumatic tubes to deliver samples for routine chemistry tests. We compared the reporting time of the automated system with that of the manual system and analyzed the distribution pattern of the specimens according to handling time. RESULTS: The median reporting time was advanced by 41 minutes, from 09:33 AM to 08:52 AM for the manual and automated reception, respectively. Moreover, with the reduction in hands-on time, the blood specimens reached the laboratory immediately after phlebotomy, thereby improving the processing efficiency by spreading out the interval during which the specimens arrived in the laboratory. Additionally, the new system allowed the identification of the phlebotomist who collected the specimens and tracking the specimens from collection to test result. CONCLUSIONS: With the introduction of our automatic reception system, the reporting time was considerably reduced. Therefore, the satisfaction of the clinician and the technical staff was improved.

Effect of the Standardization of Diagnostic Tests on the Prevalence of Diabetes Mellitus and Impaired Fasting Glucose

BACKGROUND: Without standardization of medical laboratory's testing practices, there is an increase in false diagnoses when relying on test results. However, the effect of test standardization is difficult to assess numerically. This study's purpose is to quantify the effect of the standardization level of a laboratory on the prevalence of diabetes mellitus (DM) and impaired fasting glucose (IFG). METHODS: Laboratories were classified into three levels: ‘highly-standardized laboratory,’‘basically-standardized laboratory,’ and ‘non-standardized laboratory.’ Based on the results of Korean External Quality Assessment Scheme (KEQAS), the cutoff values for diagnosis of DM and IFG were recalculated, given false positive and false negative rates. RESULTS: The prevalence of DM and IFG in the population as a whole was estimated using the 2013 Korea National Health and Nutrition Examination Survey (KNHANES) database. When the prevalence of DM from KNHANES was 11.88% (95% confidence interval [CI], 10.59%–13.17%), the proportion with a systematic false error ranged from 10.91% (95% CI, 9.65%–12.17%) to 13.09% (95% CI, 11.74%–14.45%). The prevalence of IFG varied from 13.59% (95% CI, 12.25%–14.91%) to 40.49% (95% CI, 38.54%–42.43%), in contrast to 24.58% (95% CI, 22.85%–26.31%) of the reference value. The prevalence of DM and IFG tended to be over- and under-estimated more as the laboratory standardization level became lower, respectively. CONCLUSION: Our study proved that standardization of clinical laboratory tests is an important factor affecting the prevalence estimation of national disease statistics based on the simulation using KNHANES data.

Plasma Neutrophil Gelatinase-Associated Lipocalin as a Marker of Tubular Damage in Diabetic Nephropathy

BACKGROUND: An increase in neutrophil gelatinase-associated lipocalin (NGAL) indicates tubular injury. Diabetic nephropathy causes typical changes in the kidney, characterized by glomerulosclerosis and eventual tubular damage. We validated the usefulness of plasma NGAL (pNGAL) as a biomarker of tubular damage in patients with diabetic nephropathy. METHODS: We included 376 patients with diabetes mellitus (260 patients with chronic renal insufficiency who had not received hemodialysis and 116 hemodialyzed due to diabetic nephropathy) and 24 healthy controls. Patients with chronic renal insufficiency were divided into three groups according to urinary albumin excretion (UAE) levels. pNGAL levels were measured using the Triage NGAL test (Alere, San Diego, CA, USA) and were compared between groups. We also examined whether pNGAL level was related to the degree of albuminuria and cystatin C-based glomerular filtration rate (GFR). RESULTS: Mean pNGAL levels of the healthy controls, chronic renal insufficiency patients with diabetes mellitus, and hemodialyzed patients were 61.9±5.3 ng/mL, 93.4±71.8 ng/mL, and 1,536.9±554.9 ng/mL, respectively. pNGAL level increased significantly in patients with severe albuminuria (P < 0.001) and had a moderate correlation with the degree of albuminuria (r=0.467; P < 0.001) and GFR (r=0.519; P < 0.001). Multivariate regression analysis showed that the pNGAL level was associated with tubular damage independent of patient age, sex, and GFR. CONCLUSIONS: pNGAL level independently reflects the degree of tubular damage in patients with diabetic nephropathy. Measurement of pNGAL, combined with UAE, would enable simultaneous, highly reliable assessments of tubular damage for such patients.

Report on the External Quality Assessment Scheme of Hepatitis Viral Markers in Korea, (2016–2017)

As part of the immunoserology program of the Korean Association of External Quality Assessment Service, we organized two trials on the external quality assessment of hepatitis viral markers in 2016 and 2017. The hepatitis viral antigens and antibodies program consisted of 10 test items. We delivered two and three types of pooled sera specimens to 965 and 965 institutions for the first and second trials of external proficiency testing in 2016, respectively. The number of participating laboratories was 915 (94.8%) and 913 (95.0%) in the first and second trials in 2016, respectively. We also delivered three kinds of pooled sera specimens to 936 and 1,015 institutions for the first and second trials of external proficiency testing in 2017, respectively. The number of participating laboratories was 920 (98.3%) and 996 (98.1%) in the first and second trials in 2017, respectively. The most commonly tested items were hepatitis B surface antigen, followed by the antibodies to hepatitis B surface antigen, anti-hepatitis C virus, hepatitis B envelope antigen, antibodies to hepatitis B envelope antigen, anti-hepatitis A virus and antibodies to hepatitis B core antigen. The most frequently used methods for detecting viral markers were the chemiluminescence immunoassay and the electrochemiluminescence immunoassay, but they yielded a few-false positive results due to the matrix effect. The immunochromatographic assay yielded false-negative results for anti-hepatitis A virus due to low sensitivity. Continuous improvement in the quality of viral hepatitis testing through participation in the survey seems necessary.

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.

Effect of Accreditation on Accuracy of Diagnostic Tests in Medical Laboratories

BACKGROUND: Medical laboratories play a central role in health care. Many laboratories are taking a more focused and stringent approach to quality system management. In Korea, laboratory standardization efforts undertaken by the Korean Laboratory Accreditation Program (KLAP) and the Korean External Quality Assessment Scheme (KEQAS) may have facilitated an improvement in laboratory performance, but there are no fundamental studies demonstrating that laboratory standardization is effective. We analyzed the results of the KEQAS to identify significant differences between laboratories with or without KLAP and to determine the impact of laboratory standardization on the accuracy of diagnostic tests. METHODS: We analyzed KEQAS participant data on clinical chemistry tests such as albumin, ALT, AST, and glucose from 2010 to 2013. As a statistical parameter to assess performance bias between laboratories, we compared 4-yr variance index score (VIS) between the two groups with or without KLAP. RESULTS: Compared with the group without KLAP, the group with KLAP exhibited significantly lower geometric means of 4-yr VIS for all clinical chemistry tests (P<0.0001); this difference justified a high level of confidence in standardized services provided by accredited laboratories. Confidence intervals for the mean of each test in the two groups (accredited and non-accredited) did not overlap, suggesting that the means of the groups are significantly different. CONCLUSIONS: These results confirmed that practice standardization is strongly associated with the accuracy of test results. Our study emphasizes the necessity of establishing a system for standardization of diagnostic testing.

Performance Evaluation of ADVIA Centaur XPT

We have evaluated the performance of a recently developed immunoassay analyzer, ADVIA Centaur XPT (Siemens, Germany). Precision, linearity, and comparison studies were performed according to the CLSI guidelines. The test items evaluated were ferritin, folate, human epidermal growth factor receptor 2/neu, homocysteine, vitamin B₁₂, B-type natriuretic peptide, creatine kinase–myocardial band, myoglobin, procalcitonin, troponin I. Bio-Rad control materials, linearity materials, and patients' samples were used for the evaluation. For the correlation study, ADVIA Centaur XP (Siemens) were used as comparative methods. The total coefficients of variations (CVs) of the analytes were between 2.5% and 7.0%. The results of linearity evaluation were also acceptable for the range tested. Correlations with comparative methods were good. The overall analytical performance of ADVIA Centaur XPT is acceptable for the immunology analyzer. Therefore, ADVIA Centaur XPT is expected to be widely used.

Annual Report on the External Quality Assessment Scheme for Routine Clinical Chemistry in Korea (2016)

In 2016, the clinical chemistry proficiency-testing program consisted of 21 programs, including the general chemistry program of the Korean Association of External Quality Assessment Service. The general chemistry program consisted of 28 test items and was conducted using two level control materials four times per year. Based on the information and results for each test item entered by each institution, statistical analysis data according to test method, instrument, and reagent were reported. The report comprised a general statistics report showing the characteristics of all participating institutions and a separate institutional report showing the evaluation data of individual institutions. The statistics included the number of participating institutions and the mean, standard deviation, coefficient of variation, median, minimum, and maximum values for each group. Each report was composed of a table, histogram, and Levey-Jennings chart showing the statistics for each test item. The results of each institution and the statistics for each classification are presented in the table showing the statistics, and a standard deviation index is presented together with a method classification and a classification by reagent companies. A total of 14 items, including albumin, were evaluated by more than 1,000 institutions. There was no significant difference in the distribution of the measurement methods compared with those used in the previous year. The coefficient of variation showed a tendency to increase as the concentration of the level control material decreased and as the number of participating institutions decreased for each test item. Most of them showed a coefficient of variation within 10%. These statistical data will be useful when interpreting the survey results from the institutions and selecting a test method.

Genetic Polymorphism of CYP2D6 and Clomiphene Concentrations in Infertile Patients with Ovulatory Dysfunction Treated with Clomiphene Citrate

CYP2D6 is primarily responsible for the metabolism of clomiphene citrate (CC). The purpose of the present study was to investigate the relationship between CYP2D6 genotypes, concentrations of CC and its major metabolites and drug response in infertility patients. We studied 42 patients with ovulatory dysfunction treated with only CC. Patients received a dose of 100 mg/day CC on days 3-7 of the menstrual cycle. CYP2D6 genotyping and measurement of CC and the major metabolite concentrations were performed. Patients were categorized into CC responders or non-responders according to one cycle response for the ovulation. Thirty-two patients were CC responders and 10 patients were non-responders with 1 cycle treatment. The CC concentrations were highly variable within the same group, but non-responders revealed significantly lower (E)-clomiphene concentration and a trend of decreased concentrations of active metabolites compared to the responders. Nine patients with intermediate metabolizer phenotype were all responders. We confirmed that the CC and the metabolite concentrations were different according to the ovulation status. However, our results do not provide evidence for the contribution of CYP2D6 polymorphism to either drug response or CC concentrations.

Performance Evaluation of the VISTA 500

In this study, we evaluated the performance of a recently developed immunoassay analyser, the VISTA 500 (Siemens, Germany). Precision, linearity, and comparison studies were performed according to the Clinical and Laboratory Standards Institute guidelines. The test items evaluated included IgG, IgA, IgM, C3, C4, ceruloplasmin, prealbumin, transferrin, haptoglobin, rheumatoid factor, anti-streptolysin O, and cystatin C. Commercial control materials (BioRad Laboratories, USA), commercial linearity validation materials (Maine Standards, USA), and patient samples were used for the evaluation. For the correlation study, analysis with a BN-II nephelometer (Siemens) was used as a comparative method. Total coefficients of variation of analytes were found to be between 1.9% and 5.5%. Results of the linearity evaluation were also acceptable for the range tested. Correlations with comparative methods were acceptable. The VISTA 500 analyser showed satisfactory analytical performance with respect to precision, linearity, and comparison. We conclude that the VISTA 500 is likely a good candidate as an immunology analyser.