Purpose: This study evaluated the postoperative quality of life (QoL) after various types of gastrectomy for gastric cancer. Materials and Methods: A multicenter prospective observational study was conducted in Korea using the Korean Quality of Life in Stomach Cancer Patients Study (KOQUSS)-40, a new QoL assessment tool focusing on postgastrectomy syndrome. Overall, 496 patients with gastric cancer were enrolled, and QoL was assessed at 5 time points: preoperatively and at 1, 3, 6, and 12 months after surgery. Results: Distal gastrectomy (DG) and pylorus-preserving gastrectomy (PPG) showed significantly better outcomes than total gastrectomy (TG) and proximal gastrectomy (PG) with regard to total score, indigestion, and dysphagia. DG, PPG, and TG also showed significantly better outcomes than PG in terms of dumping syndrome and worry about cancer. Postoperative QoL did not differ significantly according to anastomosis type in DG, except for Billroth I anastomosis, which achieved better bowel habit change scores than the others. No domains differed significantly when comparing double tract reconstruction and esophagogastrostomy after PG. The total QoL score correlated significantly with postoperative body weight loss (more than 10%) and extent of resection (P<0.05 for both).Reflux as assessed by KOQUSS-40 did not correlate significantly with reflux observed on gastroscopy 1 year postoperatively (P=0.064). Conclusions Our prospective observation using KOQUSS-40 revealed that DG and PPG lead to better QoL than TG and PG. Further study is needed to compare postoperative QoL according to anastomosis type in DG and PG.

Purpose: This study evaluated the postoperative quality of life (QoL) after various types of gastrectomy for gastric cancer. Materials and Methods: A multicenter prospective observational study was conducted in Korea using the Korean Quality of Life in Stomach Cancer Patients Study (KOQUSS)-40, a new QoL assessment tool focusing on postgastrectomy syndrome. Overall, 496 patients with gastric cancer were enrolled, and QoL was assessed at 5 time points: preoperatively and at 1, 3, 6, and 12 months after surgery. Results: Distal gastrectomy (DG) and pylorus-preserving gastrectomy (PPG) showed significantly better outcomes than total gastrectomy (TG) and proximal gastrectomy (PG) with regard to total score, indigestion, and dysphagia. DG, PPG, and TG also showed significantly better outcomes than PG in terms of dumping syndrome and worry about cancer. Postoperative QoL did not differ significantly according to anastomosis type in DG, except for Billroth I anastomosis, which achieved better bowel habit change scores than the others. No domains differed significantly when comparing double tract reconstruction and esophagogastrostomy after PG. The total QoL score correlated significantly with postoperative body weight loss (more than 10%) and extent of resection (P<0.05 for both).Reflux as assessed by KOQUSS-40 did not correlate significantly with reflux observed on gastroscopy 1 year postoperatively (P=0.064). Conclusions Our prospective observation using KOQUSS-40 revealed that DG and PPG lead to better QoL than TG and PG. Further study is needed to compare postoperative QoL according to anastomosis type in DG and PG.

Purpose: This study evaluated the postoperative quality of life (QoL) after various types of gastrectomy for gastric cancer. Materials and Methods: A multicenter prospective observational study was conducted in Korea using the Korean Quality of Life in Stomach Cancer Patients Study (KOQUSS)-40, a new QoL assessment tool focusing on postgastrectomy syndrome. Overall, 496 patients with gastric cancer were enrolled, and QoL was assessed at 5 time points: preoperatively and at 1, 3, 6, and 12 months after surgery. Results: Distal gastrectomy (DG) and pylorus-preserving gastrectomy (PPG) showed significantly better outcomes than total gastrectomy (TG) and proximal gastrectomy (PG) with regard to total score, indigestion, and dysphagia. DG, PPG, and TG also showed significantly better outcomes than PG in terms of dumping syndrome and worry about cancer. Postoperative QoL did not differ significantly according to anastomosis type in DG, except for Billroth I anastomosis, which achieved better bowel habit change scores than the others. No domains differed significantly when comparing double tract reconstruction and esophagogastrostomy after PG. The total QoL score correlated significantly with postoperative body weight loss (more than 10%) and extent of resection (P<0.05 for both).Reflux as assessed by KOQUSS-40 did not correlate significantly with reflux observed on gastroscopy 1 year postoperatively (P=0.064). Conclusions Our prospective observation using KOQUSS-40 revealed that DG and PPG lead to better QoL than TG and PG. Further study is needed to compare postoperative QoL according to anastomosis type in DG and PG.

Background: Korea National Health and Nutrition Examination Survey (KNHANES) triglyceride testing changed from the glycerol blanking method (2005–2021) to the glycerol nonblanking method (2022). We converted triglyceride data from 2005–2021 to that obtained since 2022 with different analytical methods. Methods: To develop a conversion equation, 98 fresh serum specimen pairs were compared using Passing–Bablok regression analysis. Implications of the conversion equation on epidemiological data were evaluated using KNHANES data from 2019–2021. Bias estimations determined using the Lipid Standardization Program (LSP) of the United States Centers for Disease Control and Prevention (CDC) enhanced the accuracy and comparability of the triglyceride results. Results: Triglyceride concentrations measured via the glycerol non-blanking method were 10.7 mg/dL (0.12 mmol/L, 10.0%) higher than those from the glycerol blanking method, with a 9.9 mg/dL (0.11 mmol/L, 5.0%) difference at a concentration of 200 mg/dL (2.26 mmol/L, N = 98). The conversion equation y (glycerol non-blanking, 2022) = 11.94+0.99x (glycerol blanking, 2005–2021) changed the mean triglyceride concentrations of the KNHANES 2019–2021 data (N = 16,015) from 123.7 mg/dL (1.40 mmol/L, 95% confidence interval [CI]: 122.2–125.1 mg/dL [1.38–1.41 mmol/L]) to 134.3 mg/dL (1.52 mmol/L, 95% CI: 132.9–135.8 mg/dL [1.50–1.53 mmol/L]). Since 2022, bias monitoring using the CDC’s LSP has remained within a 5.0% limit. Conclusions KNHANES triglyceride values in 2022 (non-blanking) were substantially higher than those from 2005–2021 (blanking). Conversion equations helped effectively adjust 2005–2021 data. Researchers should consider adjusting the KNHANES triglyceride data based on their study characteristics.

Background: Ensuring reference material (RM) commutability is crucial for evaluating measurement traceability in order to standardize laboratory tests. However, commutability assessment is not routinely performed. We assessed whether RMs prepared following CLSI C37-A guidelines could be used without assessing commutability by evaluating their commutability for four lipid measurements using the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) and CLSI EP14 protocols. Methods: We analyzed total cholesterol (TC), triglycerides (TGs), high-density lipoprotein cholesterol (HDL-C), and low-density lipoprotein cholesterol (LDL-C) in frozen sera from 20 individuals and 11 RMs, prepared by the Korea Disease Control and Prevention AgencyLaboratory Standardization Project (per CLSI C37-A), using six routine measurement procedures (MPs). Regression equations and 95% prediction intervals derived from single-donor sera were analyzed following CLSI EP14. The IFCC protocol was used to assess differences in inter-MP biases between RM and clinical samples. The effect of the TG concentration on commutability was evaluated by analyzing biases between MP results and reference procedure-assigned values. Results: RMs were commutable for most MP pairs for TC and TG. Commutability for HDL-C and LDL-C varied across RMs, with RM10 and RM11 showing higher TG levels (2.38 and 2.95 mmol/L, respectively) and lower commutability. Increased bias percentages from assigned values were observed for RMs with higher TG levels. Conclusions RMs prepared per CLSI C37-A were commutable with most MP pairs for TC and TG. Elevated TG levels affected HDL-C and LDL-C commutability, highlighting the need to consider TG concentrations during RM preparation and assess commutability to standardize laboratory tests.

Background: Commutability refers to the consistency of results from different measurement procedures in regards to a reference material (RM) and representative samples. In this study, we evaluated the commutability of laboratory-prepared pooled sera and commercial quality control materials in the thyroid-stimulating hormone (TSH) proficiency testing program of the Korean Association of External Quality Assessment Service. Methods: Serum TSH from 30 patients was measured in triplicate. Two levels of lab-prepared pooled sera and three levels of commercial materials (Bio-Rad Liquichek Immunoassay Plus) were tested in triplicate at five positions per immunoassay platform (Beckman Coulter UniCel DxI 800, Abbott Alinity i, Roche Cobas e801, Siemens Atellica IM 1600). Commutability was assessed by comparing method differences in patient samples to RMs using the ‘International Federation of Clinical Chemistry and Laboratory Medicine’ protocol with a desirable bias of 10% based on biological variation. Results: The median TSH level for the 30 patient samples was 2.51–3.07 μIU/mL, with a coefficient of variation ranging from 1.51% to 4.32%.The median TSH levels of the in-house prepared materials were 0.912– 1.01 μIU/mL for RM2 and 9.10–10.9 μIU/mL for RM4. The median TSH levels of the commercial materials were 0.391–0.464 μIU/mL for RM1, 4.39–5.24 μIU/mL for RM3, and 28.2–35.5 μIU/mL for RM5. The in-house prepared materials (RM2, RM4) demonstrated commutability across all six method combinations. Among the commercial materials, RM1 and RM3 showed commutability in four method combinations, while RM5 showed commutability in three method combinations. Conclusions The evaluation results for the TSH proficiency testing materials showed that the in-house prepared materials had higher commutability than the commercial materials.

Background: Commutability refers to the consistency of results from different measurement procedures in regards to a reference material (RM) and representative samples. In this study, we evaluated the commutability of laboratory-prepared pooled sera and commercial quality control materials in the thyroid-stimulating hormone (TSH) proficiency testing program of the Korean Association of External Quality Assessment Service. Methods: Serum TSH from 30 patients was measured in triplicate. Two levels of lab-prepared pooled sera and three levels of commercial materials (Bio-Rad Liquichek Immunoassay Plus) were tested in triplicate at five positions per immunoassay platform (Beckman Coulter UniCel DxI 800, Abbott Alinity i, Roche Cobas e801, Siemens Atellica IM 1600). Commutability was assessed by comparing method differences in patient samples to RMs using the ‘International Federation of Clinical Chemistry and Laboratory Medicine’ protocol with a desirable bias of 10% based on biological variation. Results: The median TSH level for the 30 patient samples was 2.51–3.07 μIU/mL, with a coefficient of variation ranging from 1.51% to 4.32%.The median TSH levels of the in-house prepared materials were 0.912– 1.01 μIU/mL for RM2 and 9.10–10.9 μIU/mL for RM4. The median TSH levels of the commercial materials were 0.391–0.464 μIU/mL for RM1, 4.39–5.24 μIU/mL for RM3, and 28.2–35.5 μIU/mL for RM5. The in-house prepared materials (RM2, RM4) demonstrated commutability across all six method combinations. Among the commercial materials, RM1 and RM3 showed commutability in four method combinations, while RM5 showed commutability in three method combinations. Conclusions The evaluation results for the TSH proficiency testing materials showed that the in-house prepared materials had higher commutability than the commercial materials.

Background: Commutability refers to the consistency of results from different measurement procedures in regards to a reference material (RM) and representative samples. In this study, we evaluated the commutability of laboratory-prepared pooled sera and commercial quality control materials in the thyroid-stimulating hormone (TSH) proficiency testing program of the Korean Association of External Quality Assessment Service. Methods: Serum TSH from 30 patients was measured in triplicate. Two levels of lab-prepared pooled sera and three levels of commercial materials (Bio-Rad Liquichek Immunoassay Plus) were tested in triplicate at five positions per immunoassay platform (Beckman Coulter UniCel DxI 800, Abbott Alinity i, Roche Cobas e801, Siemens Atellica IM 1600). Commutability was assessed by comparing method differences in patient samples to RMs using the ‘International Federation of Clinical Chemistry and Laboratory Medicine’ protocol with a desirable bias of 10% based on biological variation. Results: The median TSH level for the 30 patient samples was 2.51–3.07 μIU/mL, with a coefficient of variation ranging from 1.51% to 4.32%.The median TSH levels of the in-house prepared materials were 0.912– 1.01 μIU/mL for RM2 and 9.10–10.9 μIU/mL for RM4. The median TSH levels of the commercial materials were 0.391–0.464 μIU/mL for RM1, 4.39–5.24 μIU/mL for RM3, and 28.2–35.5 μIU/mL for RM5. The in-house prepared materials (RM2, RM4) demonstrated commutability across all six method combinations. Among the commercial materials, RM1 and RM3 showed commutability in four method combinations, while RM5 showed commutability in three method combinations. Conclusions The evaluation results for the TSH proficiency testing materials showed that the in-house prepared materials had higher commutability than the commercial materials.

Background: Commutability refers to the consistency of results from different measurement procedures in regards to a reference material (RM) and representative samples. In this study, we evaluated the commutability of laboratory-prepared pooled sera and commercial quality control materials in the thyroid-stimulating hormone (TSH) proficiency testing program of the Korean Association of External Quality Assessment Service. Methods: Serum TSH from 30 patients was measured in triplicate. Two levels of lab-prepared pooled sera and three levels of commercial materials (Bio-Rad Liquichek Immunoassay Plus) were tested in triplicate at five positions per immunoassay platform (Beckman Coulter UniCel DxI 800, Abbott Alinity i, Roche Cobas e801, Siemens Atellica IM 1600). Commutability was assessed by comparing method differences in patient samples to RMs using the ‘International Federation of Clinical Chemistry and Laboratory Medicine’ protocol with a desirable bias of 10% based on biological variation. Results: The median TSH level for the 30 patient samples was 2.51–3.07 μIU/mL, with a coefficient of variation ranging from 1.51% to 4.32%.The median TSH levels of the in-house prepared materials were 0.912– 1.01 μIU/mL for RM2 and 9.10–10.9 μIU/mL for RM4. The median TSH levels of the commercial materials were 0.391–0.464 μIU/mL for RM1, 4.39–5.24 μIU/mL for RM3, and 28.2–35.5 μIU/mL for RM5. The in-house prepared materials (RM2, RM4) demonstrated commutability across all six method combinations. Among the commercial materials, RM1 and RM3 showed commutability in four method combinations, while RM5 showed commutability in three method combinations. Conclusions The evaluation results for the TSH proficiency testing materials showed that the in-house prepared materials had higher commutability than the commercial materials.

Background: Commutability refers to the consistency of results from different measurement procedures in regards to a reference material (RM) and representative samples. In this study, we evaluated the commutability of laboratory-prepared pooled sera and commercial quality control materials in the thyroid-stimulating hormone (TSH) proficiency testing program of the Korean Association of External Quality Assessment Service. Methods: Serum TSH from 30 patients was measured in triplicate. Two levels of lab-prepared pooled sera and three levels of commercial materials (Bio-Rad Liquichek Immunoassay Plus) were tested in triplicate at five positions per immunoassay platform (Beckman Coulter UniCel DxI 800, Abbott Alinity i, Roche Cobas e801, Siemens Atellica IM 1600). Commutability was assessed by comparing method differences in patient samples to RMs using the ‘International Federation of Clinical Chemistry and Laboratory Medicine’ protocol with a desirable bias of 10% based on biological variation. Results: The median TSH level for the 30 patient samples was 2.51–3.07 μIU/mL, with a coefficient of variation ranging from 1.51% to 4.32%.The median TSH levels of the in-house prepared materials were 0.912– 1.01 μIU/mL for RM2 and 9.10–10.9 μIU/mL for RM4. The median TSH levels of the commercial materials were 0.391–0.464 μIU/mL for RM1, 4.39–5.24 μIU/mL for RM3, and 28.2–35.5 μIU/mL for RM5. The in-house prepared materials (RM2, RM4) demonstrated commutability across all six method combinations. Among the commercial materials, RM1 and RM3 showed commutability in four method combinations, while RM5 showed commutability in three method combinations. Conclusions The evaluation results for the TSH proficiency testing materials showed that the in-house prepared materials had higher commutability than the commercial materials.