Immunosuppressive Drug Measurement by Liquid Chromatography Coupled to Tandem Mass Spectrometry: Interlaboratory Comparison in the Korean Clinical Laboratories

Background@#Liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) is increasingly used for immunosuppressive drug tests. However, most LC-MS/MS tests are laboratory-developed and their agreement is unknown in different Korean laboratories.This interlaboratory comparison study evaluated test reproducibility and identified potential error sources. @*Methods@#Test samples containing three concentrations of tacrolimus, sirolimus, everolimus, cyclosporine, and mycophenolic acid were prepared by pooling surplus samples from patients undergoing routine therapeutic drug monitoring and tested in duplicate in the participating 10 clinical laboratories. Reconstitution and storage experiments were conducted for the commonly used commercial calibrator set. The robust estimators of reproducibility parameters were calculated. Spearman’s rank correlation coefficient (rho, ρ) was used to evaluate the correlation between drugs. Multiple linear regression was used to determine whether the experimental conditions alter the calibration curves. @*Results@#The reproducibility coefficient of variation exceeded 10% only for sirolimus concentrations 1 and 2 (10.8% and 12.5%, respectively) and everolimus concentrations 1 and 2 (12.3% and 11.4%, respectively). The percent difference values showed weak correlations between sirolimus and everolimus (ρ = 0.334, P = 0.175). The everolimus calibration curve slope was significantly altered after reconstitution following prolonged 5°C storage (P = 0.015 for 14 days; P = 0.025 for 28 days); the expected differences at 6 ng/mL were 0.598% for 14 days and 0.384% for 28 days. @*Conclusions@#LC-MS/MS test reproducibility for immunosuppressive drugs seems to be good in the Korean clinical laboratories. Continuous efforts are required to achieve test standardization and harmonization, especially for sirolimus and everolimus.

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.

Annual Report of the Korean Association of External Quality Assessment Service on General Chemistry (2019)

In 2019, the general chemistry proficiency testing program of the Korean Association of External Quality Assessment Service consisted of routine chemistry and urine chemistry programs including 30 and 13 test items, respectively. The test method classification system in the urine chemistry program was revised. The routine chemistry program was conducted four times a year, and the urine chemistry program was conducted twice a year.Statistical analysis data for the test method and reagent companies were reported based on the information and results of the test items provided by each institution. The statistics included the number of participating institutes, mean, standard deviation, coefficient of variation (CV), median, and the minimum and maximum values for each group. Each report included tables, histograms, Levey–Jennings charts, and the standard deviation index showing the statistics of each test item. In the routine chemistry program, more than 1,000 institutions performed 17 test items, and the number is continuously increasing. Alkaline phosphatase and lactate dehydrogenase were found to have relatively high CVs because of the differences in the results obtained using different test methods; however, the CVs for others were within 10%. In the urine chemistry program, albumin and protein showed relatively high CVs.

Turnaround Time (TAT) Setting Status of 30 Domestic Clinical Laboratories and Consideration for Improvement and Management of TAT

Background@#Turnaround time (TAT) is a major quality control indicator and can be defined differently depending on the starting point in the examination process. To determine effective TAT management plan, we investigated the status of TAT management in clinical laboratories in Korea. @*Methods@#A questionnaire was developed using Google web pages and a questionnaire survey was conducted at 30 clinical laboratories in laboratory medicine from September 1 to 11 in 2018. Questions were developed regarding management time, starting point standards, management goals, most problematic stages of delayed TAT, clinical measures, and shortening barriers for investigation. @*Results@#All clinical laboratories requested to undertake the survey completed the questionnaire (response rate 100%, 30/30) and answered that they were setting and managing TAT for all tests. Many laboratories (33%) set the TAT starting point as the reception stage, prior to commencing centrifugation. Of the surveyed laboratories, 37% achieved a TAT of 120 min or more for general tests, 27% met the TAT of 90 min for pre-clinic tests, and 77% met the TAT of 60 min for completion of stat tests. Most laboratories (67%) reported that the most delayed stage was pre-analysis, and 50% reported that the greatest obstacle to shortening TAT was the ratio of stat and pre-clinic tests to general tests. @*Conclusions@#The laboratories participating in this survey set a TAT based on various criteria and were performing management for TAT improvement. The results of this study can be used as basic data to guide efficient TAT management.

Turnaround Time (TAT) Setting Status of 30 Domestic Clinical Laboratories and Consideration for Improvement and Management of TAT

Background@#Turnaround time (TAT) is a major quality control indicator and can be defined differently depending on the starting point in the examination process. To determine effective TAT management plan, we investigated the status of TAT management in clinical laboratories in Korea. @*Methods@#A questionnaire was developed using Google web pages and a questionnaire survey was conducted at 30 clinical laboratories in laboratory medicine from September 1 to 11 in 2018. Questions were developed regarding management time, starting point standards, management goals, most problematic stages of delayed TAT, clinical measures, and shortening barriers for investigation. @*Results@#All clinical laboratories requested to undertake the survey completed the questionnaire (response rate 100%, 30/30) and answered that they were setting and managing TAT for all tests. Many laboratories (33%) set the TAT starting point as the reception stage, prior to commencing centrifugation. Of the surveyed laboratories, 37% achieved a TAT of 120 min or more for general tests, 27% met the TAT of 90 min for pre-clinic tests, and 77% met the TAT of 60 min for completion of stat tests. Most laboratories (67%) reported that the most delayed stage was pre-analysis, and 50% reported that the greatest obstacle to shortening TAT was the ratio of stat and pre-clinic tests to general tests. @*Conclusions@#The laboratories participating in this survey set a TAT based on various criteria and were performing management for TAT improvement. The results of this study can be used as basic data to guide efficient TAT management.

Design and Laboratory Implementation of Web Application for Collaboratively Setting Reference Intervals / 임상검사와정도관리

BACKGROUND: Although the same equipment and reagents can be employed for inspecting identical samples, the setting and verification methods for the corresponding reference intervals differ from each other, and such methods are not well established. To address the issues associated with establishing and validating reference intervals, a Web-based application is proposed for collaboratively setting reference intervals. METHODS: A Web application was designed for automatically providing the statistical results associated with a reference interval upon receiving the corresponding test results from participating institutions and incorporating the cumulative data. RESULTS: By employing the proposed Web-based application (www.referencerange.org), reference intervals can be collaboratively set based on objective and statistical analyses incorporating clinical chemistry results obtained from Korea Healthcare Association in the years 2016 and 2017. Cumulative data obtained from the existing input peer group associated with an inspection are updated in real time, and the current set reference interval is displayed in real time. CONCLUSIONS: In this study, a Web-based application is designed for collaboratively setting reference intervals whereby all Korean laboratories can easily participate, collectively set reference intervals, and apply the set reference intervals. Hence, the proposed application can aid in providing basic data associated with health information.

Annual Report of the Korean Association of External Quality Assessment Service on General Chemistry (2018) / 임상검사와정도관리

In 2018, the general chemistry proficiency testing program of the Korean Association of External Quality Assessment Service consisted of the routine chemistry and urine chemistry programs including 32 and 13 test items, respectively. The test method classification system was revised in the routine chemistry program, and a qualitative test of human chorionic gonadotropin was added in the urine chemistry program. The routine chemistry program was conducted 4 times a year, while the urine chemistry program was conducted twice a year. Statistical analysis data for the test method and reagent companies were reported based on the information and results of the test items provided by each institution. Statistics included the number of participating institutes, mean, standard deviation, coefficient of variation (CV), median, and minimum and maximum values for each group. Each report included tables, histograms, Levey-Jennings charts, and the standard deviation index showing the statistics of each test item. In the routine chemistry program, more than 1,000 institutions performed the 17 test items, and the number is continuously increasing. CV for each test item showed a tendency to increase with decreasing concentration of the proficiency material but was within 10% in most cases. Alkaline phosphatase and lactate dehydrogenase were found to have relatively high CVs because of the differences in results among test methods. In the urine chemistry program, albumin and protein showed high CVs, and the distribution of the test method was different from that of the routine chemistry program.

Performance Evaluation of the ARCHITECT i2000 for the Determination of Whole Blood Cyclosporin A and Tacrolimus / 임상검사와정도관리

Maintaining immunosuppressant concentrations within the therapeutic range in organ recipients requires regular monitoring. The blood concentrations of immunosuppressants are routinely measured using one of several automated immunoassays, such as chemiluminescence immunoassays (CLIAs) and liquid chromatography-tandem mass spectrometry (LC-TMS). The ARCHITECT i2000 immunoassay analyzer (Abbott Diagnostics, USA) was developed as an automated CLIA analyzer for the measurement of cyclosporin A and tacrolimus in whole blood. Here, the precision and linearity of the ARCHITECT i2000 analyzer for the detection of cyclosporin A and tacrolimus in whole blood were evaluated according to Clinical and Laboratory Standards Institute guidelines and were compared with those of an LC-TMS detection method. The total coefficient of variation for the two drugs was less than 10%, and they showed linearity values of 0.97 or more, which was within the manufacturer's range. The measurements of both immunosuppressants by the ARCHITECT i2000 were closely correlated with measurements determined by LC-TMS. However, most measurements were lower with LC-TMS than with the ARCHITECT i2000. Measurement of cyclosporin A and tacrolimus in whole blood using the ARCHITECT i2000 showed very satisfactory performance in terms of precision and linearity as well as good correlation with the comparative method.

A Questionnaire Survey on General Status and Opinions about Clinical Mass Spectrometric Analysis in Korea (2018)

The Clinical Mass Spectrometry Research Committee (CMSRC), in affiliation with the Korean Society of Clinical Chemistry (KSCC), conducted a questionnaire survey on opinions about the general status of clinical mass spectrometric analysis in Korea. As a result, we understand that this field has passed through the introductory stage and is settled as a field of clinical laboratory testing in Korea, with the number of new laboratories performing mass spectrometric analysis being low. In spite of the many difficulties in introducing and operating clinical mass spectrometric analysis, there is a strong interest in this field, and even though further expansion is expected, there are still many issues to be resolved. In the future, it will be necessary to make concrete and thorough efforts to further develop the laboratory tests using clinical mass spectrometric analysis in Korea, centering on the CMSRC affiliated with the KSCC.

Association between vitamin D level at birth and respiratory morbidities in very-low-birth-weight infants / 소아과

PURPOSE: This study aimed to evaluate vitamin D status at birth in very-low-birth-weight infants (VLBWIs: <1,500 g) and to determine the association between vitamin D level and respiratory morbidity. METHODS: A retrospective study was conducted at Soonchunhyang University Bucheon Hospital between November 2013 and November 2017. We collected blood samples and data on respiratory morbidity from 230 VLBWIs on the first day of life. Patients who were transferred to other hospitals (n=19), died before 36 weeks of gestational age (n=18), or whose blood samples were not collected immediately after birth (n=5) were excluded. Finally, 188 patients were enrolled. VLBWIs with different vitamin D levels were compared with respect to demographic features, maternal diseases, respiratory morbidities, and other neonatal diseases. RESULTS: The mean serum vitamin D level, as measured by 25-hydroxyvitamin D (25(OH)D), was 13.4±9.3 ng/mL. The incidence of vitamin D deficiency (<20 ng/mL) was 79.8%, and 44.1% of preterm infants had severe vitamin D deficiency (<10 ng/mL). Logistic analysis shows that a low serum 25(OH)D level (<20 ng/mL) was a risk factor for respiratory distress syndrome (odds ratio [OR], 4.32; P=0.010) and bronchopulmonary dysplasia (OR, 4.11; P=0.035). CONCLUSION: The results showed that 79.8% of preterm infants in this study had vitamin D deficiency at birth. Low vitamin D status was associated with respiratory morbidity, but the exact mechanism was unknown. Additional studies on the association between vitamin D level and neonatal morbidity are required.

Development of Statistical Software for the Korean Laboratory Accreditation Program Using R Language: LaboStats

BACKGROUND: In Korea, the Korean Laboratory Accreditation Program (KLAP) has set minimum standards for verification of clinical test performance. This verification process is time-consuming and labor-intensive when performed manually. We developed a free, statistical software program for KLAP, using the R language (R Foundation for Statistical Computing, Vienna, Austria). METHODS: We used CLSI guidelines for the algorithm. We built graphic user interfaces, including data input, with Embarcadero Delphi EX4 (Embarcadero Technologies, Inc., Texas, USA). The R Base Package and MCR Package for Method Comparison Regression were used to implement statistical and graphical procedures. RESULTS: Our program LaboStats has six modules: parallel test, linearity, method comparison, precision, reference interval, and cutoff. Data can be entered into the field either manually or by copying and pasting from an MS Excel worksheet. Users can print out precise reports. CONCLUSIONS: LaboStats can be useful for evaluating clinical test performance characteristics and preparing documents requested by KLAP.

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

No abstract available.

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.

Annual Report on the External Quality Assessment Scheme for General Chemistry in Korea (2017)

In 2017, the clinical chemistry proficiency testing program consisted of 24 programs with the addition of the urine chemistry program in the Korean Association of External Quality Assessment Service. The routine chemistry program consisted of 32 test items, including osmolality, total CO2, and estimated glomerular filtration rate tests, and the urine chemistry program consisted of 12 test items, including the albumin test. Based on the information and results of each test item entered by each institution, statistical analysis data according to test method, instrument, and reagent were reported. The statistics included the number of participating institutions, mean, standard deviation, coefficient of variation, median, minimum, and maximum values for each group. Each report was composed of a table, histogram, Levy-Jennings chart, and standard deviation index showing statistics by each test item. A total of 14 items, including albumin, were evaluated by more than 1,000 institutions, and the number of participating institutions is continuously increasing. The coefficient of variation tended to increase, as the concentration of the control material was lower for each test item. Most of them showed a coefficient of variation within 10%. Alkaline phosphatase and lactate dehydrogenase were found to have high coefficients of variation due to differences in measurement values between measurement methods. The distribution of measurement methods in general chemistry test items was not significantly different from that of previous years, and the distribution of measurement methods for albumin, glucose, phosphorus, and protein among the urine chemistry program was different from that of the routine chemistry program.

Performance Evaluation of the Afinion AS100 Analyzer for Its Use in the Albumin Creatinine Ratio Test

BACKGROUND: Early detection of moderately increased albuminuria using the albumin-creatinine ratio (ACR) test is very important for preventing renal insufficiency and cardiovascular disease in patients with diabetes. The purpose of this study was to analyse the clinical usefulness of the Afinion AS100 Analyzer (Alere Technologies AS, Norway) for determining the ACR by evaluating its precision and linearity and comparing it with another conventional device. METHODS: Urine samples of patients and quality control materials were used for evaluation. The Afinion AS100 was used to measure albumin and creatinine, and the ACR was automatically calculated. The Cobas Integra 800 (Roche Diagnostics, Germany) was used as a reference instrument for correlation analysis. In accordance with the Clinical and Laboratory Standards Institute guidelines, precision, linearity, and turnaround time were evaluated, and the Afinion AS100 was compared with another device. RESULTS: The total coefficients of variation of albumin and creatinine were 2.8% and 2.9% for high concentration and 2.9% and 2.5% for low concentration, respectively. Both albumin and creatinine showed coefficients of determination of 0.999 or higher in linearity. Correlation coefficients of albumin, creatinine, and ACR were higher than the Clinical and Laboratory Standards Institute recommended value of 0.975, suggesting a high correlation as well as showing significant correlation with a 24-hour urinary albumin level obtained using the Cobas Integra 800. Mean turnaround time was 5 minute 35 seconds. CONCLUSIONS: The albumin, creatinine, and ACR tests performed with the Afinion AS100 showed satisfactory performance in terms of precision and linearity and showed good correlation with the central laboratory instrument and a 24-hour urine albumin quantitative test using a conventional instrument.

Performance Evaluation of STRATUS CS200 for Cardiac Markers

The STRATUS CS200 (Siemens Healthcare Diagnostics Inc., USA) has recently been developed as an on-site diagnostic instrument for assaying several kinds of cardiac markers within a short duration. The precision, linearity, comparison, limit of quantification, and turnaround time (TAT) were evaluated for troponin I, creatine kinase-MB (CK-MB), N-terminal pro-brain natriuretic peptide (NT-proBNP), and myoglobin assays according to guidelines provided by the Clinical and Laboratory Standards Institute. The total coefficients of variation of the four items were between 1.90% and 4.25%. All markers showed a linearity that was ≥0.99, and the values were within the manufacturer's range. All items showed a close correlation with E170 (Roche Diagnostics, Germany). The limits of quantification for troponin I, CK-MB, myoglobin, and NT-proBNP were 0.03 ng/mL, 0.3 ng/mL, 1 ng/mL, and 15 pg/mL, respectively. The TAT was 14 minutes. The performance of the STRATUS CS200 for assaying cardiac markers was highly satisfactory in terms of the precision, linearity, limit of quantification, and TAT, and it showed a good correlation with the comparative method.

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.

A Case of Chronic Myeloid Leukemia With Rare Variant ETV6/ABL1 Rearrangement

No abstract available.

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.