Gender differences in hepatitis A seropositivity rates according to the Republic of Korea's vaccination policy.

BACKGROUND: This study aimed to investigate differences in the anti-hepatitis A virus (HAV) antibody seropositivity rate by age and gender. METHODS: We collected information on anti-HAV immunoglobulin G and immunoglobulin M status from samples submitted for HAV antibody testing in 2012-2022. A total of 1,333,615 cases were included in the analysis. RESULTS: By age, the seropositivity rate was represented by a U-shaped curve, such that the rate was low for the group aged 20 to 39 years and higher in those who were younger or older. Over time, the curve shifted rightward, and the seropositivity rate declined gradually in the group aged 35 to 39 years and older. A gender-based difference in antibody seropositivity rate was especially noticeable in the group aged 20 to 29 years. This difference between genders widened in the participants' early 20s-when men in the Republic of Korea enlist in the military-and the divergence continued subsequently for older individuals. CONCLUSION: These results indicate a higher risk of severe infection among older individuals and a gender-based difference in seroprevalence. Therefore, it is necessary to implement policies to promote vaccination in adults.

Lipid distributions in the Global Diagnostics Network across five continents.

AIMS: Lipids are central in the development of cardiovascular disease, and the present study aimed to characterize variation in lipid profiles across different countries to improve understanding of cardiovascular risk and opportunities for risk-reducing interventions. METHODS AND RESULTS: This first collaborative report of the Global Diagnostics Network (GDN) evaluated lipid distributions from nine laboratory organizations providing clinical laboratory testing in 17 countries on five continents. This cross-sectional study assessed aggregated lipid results from patients aged 20-89 years, tested at GDN laboratories, from 2018 through 2020. In addition to mean levels, the World Health Organization total cholesterol risk target (<5.00 mmol/L, <193 mg/dL) and proportions in guideline-based low-density lipoprotein cholesterol (LDL-C) categories were assessed. This study of 461 888 753 lipid results found wide variation by country/region, sex, and age. In most countries, total cholesterol and LDL-C peaked at 50-59 years in females and 40-49 years in males. Sex- and age-group adjusted mean total cholesterol levels ranged from 4.58 mmol/L (177.1 mg/dL) in the Republic of Korea to 5.40 mmol/L (208.8 mg/dL) in Austria. Mean total cholesterol levels exceeded the World Health Organization target in Japan, Australia, North Macedonia, Switzerland, Germany, Slovakia, and Austria. Considering LDL-C categories, North Macedonia had the highest proportions of LDL-C results >4.91 mmol/L (>190 mg/dL) for both females (9.9%) and males (8.7%). LDL-C levels <1.55 mmol/L (<60 mg/dL) were most common among females in Canada (10.7%) and males in the UK (17.3%). CONCLUSION: With nearly a half billion lipid results, this study sheds light on the worldwide variability in lipid levels, which may reflect inter-country differences in genetics, lipid testing, lifestyle habits, and pharmacologic treatment. Despite variability, elevated atherogenic lipid levels are a common global problem, and these results can help inform national policies and health system approaches to mitigate lipid-mediated risk of cardiovascular disease.

Development of Certified Reference Material for Amino Acids in Dried Blood Spots and Accuracy Assessment of Disc Sampling.

To achieve the measurement reliability of amino acids used as diagnostic markers in clinical fields, establishing a reference measurement system is required, in which certified reference materials (CRMs) are an essential step in the hierarchy of measurement traceability. This study describes the development of dried blood spot (DBS) CRMs for amino acid analysis with complete measurement traceability to the International System of Units (SI). Six essential amino acids─proline, valine, isoleucine, leucine, phenylalanine, and tyrosine─were analyzed using isotope-dilution liquid chromatography-mass spectrometry (ID-MS). For minimizing measurement bias and uncertainty overestimation, whole spots with 50 µL of whole blood were adopted in the certification. The between-spot homogeneities by whole spot sampling were lower than 2.1%. The relative expanded uncertainties of the six amino acids in the developed DBS CRMs were lower than 5.7% at 95% confidence. The certified values are traceable to SI through both gravimetric preparation and the primary method in certification, ID-MS. Comparison among DBS testing laboratories revealed discrepancies between the whole spot and disc sampling methods. The actual sampling volume was accurately estimated by weighing, which revealed the possibility of underestimation in routine DBS testing. The candidate CRMs can support the standardization of DBS testing for amino acids through the qualification and validation of many kinds of measurement procedures to compensate the measurement bias caused by matrix-specific sampling error.

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.

Performance evaluation of Samsung LABGEO(HC10) Hematology Analyzer.

CONTEXT: The Samsung LABGEO(HC10) Hematology Analyzer (LABGEO(HC10)) is a recently developed automated hematology analyzer that uses impedance technologies. The analyzer provides 18 parameters including 3-part differential at a maximum rate of 80 samples per hour. OBJECTIVE: To evaluate the performance of the LABGEO(HC10). DESIGN: We evaluated precision, linearity, carryover, and relationship for complete blood cell count parameters between the LABGEO(HC10) and the LH780 (Beckman Coulter Inc) in a university hospital in Korea according to the Clinical and Laboratory Standards Institute guidelines. Sample stability and differences due to the anticoagulant used (K2EDTA versus K3EDTA) were also evaluated. RESULTS: The LABGEO(HC10) showed linearity over a wide range and minimal carryover (<1%) for white blood cell, hemoglobin, red blood cell, and platelet parameters. Correlation between the LABGEO(HC10) and the LH780 was good for all complete blood cell count parameters (R > 0.92) except for mean corpuscular hemoglobin concentration. The bias estimated was acceptable for all parameters investigated except for monocyte count. Most parameters were stable until 24 hours both at room temperature and at 4°C. The difference by anticoagulant type was statistically insignificant for all parameters except for a few red cell parameters. CONCLUSIONS: The accurate results achievable and simplicity of operation make the unit recommendable for small to medium-sized laboratories.

Current routine practice and clinico-pathological characteristics associated with acute promyelocytic leukemia in Korea.

BACKGROUND: Acute promyelocytic leukemia (APL) can be life threatening, necessitating emergency therapy with prompt diagnosis by morphologic findings, immunophenotyping, cytogenetic analysis, or molecular studies. This study aimed to assess the current routine practices in APL and the clinico-pathologic features of APL. METHODS: We reviewed the medical records of 48 Korean patients (25 men, 23 women; median age, 51 (20-80) years) diagnosed with APL in 5 university hospitals between March 2007 and February 2012. RESULTS: The WBC count at diagnosis and platelet count varied from 0.4 to 81.0 (median 2.0)×10(9)/L and 2.7 to 124.0 (median 54.5)×10(9)/L, respectively. The median values for prothrombin time and activated partial thromboplastin time were 14.7 (11.3-44.1) s and 29 (24-62) s, respectively. All but 2 patients (96%) showed a fibrin/fibrinogen degradation product value of >20 µg/mL. The D-dimer median value was 5,000 (686-55,630) ng/mL. The t(15;17)(q22;q12 and PML-RARA fusion was found in all patients by chromosome analysis and/or multiplex reverse transcriptase-polymerase chain reaction (RT-PCR), with turnaround times of 8 (2-19) d and 7 (2-13) d, respectively. All patients received induction chemotherapy: all-trans retinoic acid (ATRA) alone (N=11, 26%), ATRA+idarubicin (N=25, 58%), ATRA+cytarabine (N=3, 7%), ATRA+idarubicin+cytarabine (N=4, 9%). CONCLUSION: Since APL is a medical emergency and an accurate diagnosis is a prerequisite for prompt treatment, laboratory support to implement faster diagnostic tools to confirm the presence of PML-RARA is required.