Original Article2022-07-01 Clinical Chemistry
Hyun Suk Yang 
, M.D., Ph.D., Ho Jin Jeong , M.S., Hyeongsu Kim , M.D., Ph.D., Hweung Kon Hwang , M.D., Ph.D., Mina Hur , M.D., Ph.D., and Seungho Lee , Ph.D.
Abstract : Background: High-density lipoprotein cholesterol (HDL-C) is a well-known predictor of atherosclerotic cardiovascular diseases (ASCVD). We explored the relationships between HDL-C levels and 10-year major adverse cardiovascular events (MACE) and provided sex-specific upper reference limits for HDL-C levels. Methods: Based on the Korean National Health Insurance Sharing Service, we identified 5,703,897 subjects (women, 48%) with age ≥40 years, eligible HDL-C results, and no prior ASCVD in 2009. We investigated the distribution of 10-year MACE according to HDL-C levels in 10 mg/dL (0.26 mmol/L) intervals and in three HDL-C groups (low: men
Brief Communication2021-07-01 Diagnostic Hematology
Mi Suk Park , Ph.D., Young Eun Lee , M.S., Hye Ran Kim , Ph.D., Jong Hee Shin , M.D., Ph.D., Hyun Wook Cho , Ph.D., Jun Hyung Lee , M.D., Ph.D., and Myung Geun Shin , M.D., Ph.D.
Abstract : Phospholipase C beta 2 (PLC-β2) regulates various essential functions in cell signaling, differentiation, growth, and mobility. We investigated the clinical implications of PLC-β2 protein expression in newly diagnosed normal karyotype acute myeloid leukemia (NK-AML). The PLC-β2 expression status in bone marrow tissues obtained from 101 patients with NK-AML was determined using semiquantitative immunohistochemistry (IHC). IHC results were compared with those for known prognostic markers. Using a cutoff score for positivity of 7.0, the PLC-β2 overexpression group showed superior overall survival (OS) (72.6% vs. 26.5%; P=0.016) and low hazard ratio (HR) (0.453; P=0.019) compared with the PLC-β2 low-expression group. The PLC-β2 overexpression group showed no significant gain in event-free survival (50.6% vs. 43.0%, P=0.465) and HR (0.735; P=0.464). Among the known prognostic markers, only FLT3-ITD positivity was associated with a significantly low OS and high HR. In conclusion, PLC-β2 overexpression was associated with favorable OS in NK-AML patients. Our results suggest that PLC-β2 expression assessment using IHC allows prognosis prediction in NK-AML.
Original Article2022-03-01 Clinical Chemistry
Youngwon Nam , M.D., Joon Hee Lee , M.D., Sung Min Kim , M.T., Sun-Hee Jun , M.T., Sang Hoon Song , M.D., Ph.D., Kyunghoon Lee , M.D., and Junghan Song , M.D., Ph.D.
Abstract : Background: Results from laboratories using multiple instruments should be standardized or harmonized and comparability-verified for consistent quality control. We developed a simple frequent comparability verification methodology applicable to large healthcare centers using multiple clinical chemistry instruments from different manufacturers. Methods: Comparability of five clinical chemistry instruments (Beckman Coulter AU5800, Abbott Architect Ci16000, two Siemens Vista 1500, and Ortho Vitros 5600) was evaluated from 2015 to 2019 for 12 clinical chemistry measurements. Pooled residual patient samples were used for weekly verifications. Results from any instrument exceeding the allowable verification range versus the results from the comparative instrument (AU5800) were reported to clinicians after being multiplied by conversion factors that were determined via a linear regression equation obtained from simplified comparison. Results: Over the five-year study period, 432 weekly inter-instrument comparability verification results were obtained. Approximately 58% of results were converted due to non-comparable verification. Expected average absolute percent bias and percentage of non-comparable results for non-converted and converted results after conversion action were much lower than those for data measured before conversion action. The inter-instrument CV for both non-converted and converted results after conversion action was much lower than that for measured data before conversion action for all analytes. Conclusions: We maintained within-laboratory comparability of clinical chemistry tests from multiple instruments for five years using frequent low-labor periodic comparability verification methods from pooled residual sera. This methodology is applicable to large testing facilities using multiple instruments.
Brief Communication2022-07-01 Clinical Microbiology
Tae Yeul Kim , M.D., Ji-Youn Kim , M.T., Hyang Jin Shim , M.T., Sun Ae Yun , M.T., Ja-Hyun Jang , M.D., Hee Jae Huh , M.D., Jong-Won Kim , M.D., and Nam Yong Lee , M.D.
Abstract : Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) and influenza viruses may pose enormous challenges to our healthcare system. We evaluated the performance of the PowerChek SARS-CoV-2, Influenza A & B Multiplex Real-time PCR Kit (PowerChek; Kogene Biotech, Seoul, Korea) in comparison with the BioFire Respiratory Panels 2 and 2.1 (RP2 and RP2.1; bioMérieux, Marcy l’Étoile, France), using 147 nasopharyngeal swabs. The limit of detection (LOD) of the PowerChek assay was determined using SARS-CoV-2, influenza A, and B RNA standards. The LOD values of the PowerChek assay for SARS-CoV-2 and influenza A and B were 1.12, 1.24, and 0.61 copies/μL, respectively. The positive and negative percent agreements of the PowerChek assay compared with RP2 and RP2.1 were 97.5% (39/40) and 100% (107/107) for SARS-CoV-2; 100% (39/39) and 100% (108/108) for influenza A; and 100% (35/35) and 100% (112/112) for influenza B, respectively. The performance of the PowerChek assay was comparable to that of RP2 and RP2.1 for detecting SARS-CoV-2 and influenza A and B, suggesting its use in diagnosing SARS-CoV-2 and influenza infections.
Brief Communication2021-09-01 Clinical Chemistry
Isidor Minović , Pharm.D., Ph.D., Lambert D. Dikkeschei , Ph.D., Michel J. Vos , Ph.D., and Jenny E. Kootstra-Ros , Ph.D.
Abstract : Folate analysis in plasma is affected by hemolysis, which can lead to biased results. However, the degree of hemolysis that is considered acceptable is unclear. We explored the relationship between folate concentration and degree of hemolysis. Heparin plasma samples (N=77, hemolysis index ≤10 μmol/L) were spiked with increasing amounts of corresponding patient-specific hemolysate. Subsequently, the folate concentration and hemolysis index were measured using two Roche Cobas platforms, and their incremental relationship was investigated. The folate concentration ranged from 2.9 to 30.9 nmol/L with a median (interquartile range) of 11.4 (8.6-19.1) nmol/L. The linear relationship between the increments in folate concentration and hemolysis index was approximated by the function y=1.86x+1.56 (R2=0.996), where x represents the laboratory-specific critical difference in folate concentration, which can be calculated from the analytical variation of the employed folate assay(s), and y represents the hemolysis threshold. The hemolysis threshold did not significantly differ between the tertiles of plasma folate concentration (P=0.10). In conclusion, we have provided an evidence-based approach that can be used to reliably interpret folate concentrations in hemolytic samples, independent of the patient’s folate status.
Original Article2022-05-01 Transfusion Medicine
Mikyoung Park , M.D., Ph.D., Mina Hur , M.D., Ph.D., Hahah Kim , M.D., Ph.D., Kyungmi Oh , R.N., Ph.D., Hyunmi Kim , R.N., Young Hye Song , R.N., Ph.D., Dae-Hyun Ko , M.D., Ph.D., and Yousun Chung , M.D.
Abstract : Background: To ensure safe red blood cell (RBC) transfusion practice, it is important to comply with storage and transport requirements of RBC units. We conducted a comprehensive survey on the practice of RBC transport and storage to explore the awareness of and compliance with the 30-minute rule, the current status of RBC unit transport, and possible utility of temperature indicators (TIs) to reduce RBC wastage. Methods: From June to August of 2019, 64 blood bank physicians (14 questions) in 64 secondary- and tertiary-care hospitals and 673 nurses (13 questions) in 42 tertiary-care hospitals replied to a questionnaire survey. The results of the survey were analyzed with descriptive statistics. Results: Among the physicians surveyed, 97.0% (N=62) of hospitals had transfusion guidelines in place. The RBC wastage in 2018 ranged from less than five units to more than 200 units. Among the nurses surveyed, 99.4% (N=669) were aware of and complied with the 30-minute rule; 13.5% (N=91) of the nurses had experience of RBC wastage due to violation of the 30-minute rule. Both physicians (67%, N=43) and nurses (83.1%, N=559) responded that TIs would help reduce RBC wastage. Conclusions: This is the first survey on the practices related to RBC transport and storage in Korea. This study provides fundamental data on current practice for the blood cold chain, insights into RBC wastage, and highlights the utility of TIs.
Original Article2022-09-01 Diagnostic Hematology
Hyun-Young Kim , M.D., In Young Yoo , M.D., Dae Jin Lim , M.T., Hee-Jin Kim , M.D., Sun-Hee Kim , M.D., Sang Eun Yoon , M.D., Seok Jin Kim , M.D., Duck Cho , M.D., and Kihyun Kim , M.D.
Abstract : Background: Minimal residual disease (MRD) is an important prognostic factor for evaluating a deeper treatment response in patients with multiple myeloma (MM). We evaluated the clinical utility of next-generation flow (NGF)-based MRD assessment in a heterogeneous MM patient population. Methods: Patients with suspected morphological remission after or during MM treatment were prospectively enrolled. In total, 108 bone marrow samples from 90 patients were analyzed using NGF-based MRD assessment according to the EuroFlow protocol, and progression-free survival (PFS) was evaluated according to the International Myeloma Working Group response status, cytogenetic risk, and MRD status. Results: The overall MRD-positive rate was 31.5% (34/108 samples), and MRD-positive patients showed a lower PFS than MRD-negative patients (P=0.005). MRD-positive patients showed inferior PFS than MRD-negative in patients with stringent complete remission (sCR)/complete remission (P=0.014) and high-risk cytogenetic abnormalities (P=0.016). MRD was assessed twice in 18 patients with a median interval of 12 months. Sustained MRD negativity was only observed in patients with sustained sCR, and their PFS was superior to that of patients who were not MRD-negative (P=0.035). Conclusions: Clinical application of NGF-based MRD assessment can provide valuable information for predicting disease progression in patients with MM in remission, including those with high-risk cytogenetic abnormalities.
Letter to the Editor2022-03-01 Diagnostic Hematology
Hongkyung Kim , M.D., Hye Min Kim , M.D., Jin Ju Kim , M.D., Saeam Shin , M.D., Doh Yu Hwang , M.D., Seung-Tae Lee , M.D., and Jong Rak Choi , M.D.
Original Article2021-07-01 Clinical Chemistry
Tae-Dong Jeong , M.D., Ph.D., Eun-Jung Cho , M.D., Ph.D., Kyunghoon Lee , M.D., Ph.D., Woochang Lee , M.D., Ph.D., Yeo-Min Yun , M.D., Ph.D., Sail Chun , M.D., Ph.D., Junghan Song , M.D., Ph.D., and Won-Ki Min , M.D., Ph.D.
Abstract : 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.
Letter to the Editor2021-09-01 Diagnostic Genetics
Beatriz González Fernández , M.S., José Bartolomé Nieto Campuzano , M.D., Dolores García Rocamora , M.D., Jorge M Nieto , M.S., Fernando Ataúlfo González Fernández , M.D., Ana Villegas , M.D., Ph.D., Celina Benavente Cuesta , M.D., and Paloma Ropero , Ph.D.
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