Prevalence and factors influencing anemia recovery after intensive care.

BACKGROUND: Anemia is associated with adverse outcomes and prolonged hospitalizations in critically ill patients. Regarding the recent adoption of restrictive transfusion protocols in intensive care unit (ICU) management, anemia remains highly prevalent even after ICU discharge. This study aimed to investigate the prevalence of anemia following ICU discharge and factors affecting recovery from anemia. METHODS: In this retrospective cohort study involving 3969 adult ICU survivors, we assessed anemia severity using the National Cancer Institute criteria at six time points: ICU admission, ICU discharge, hospital discharge, and at 3-, 6-, and 12-month post-hospital discharge. In addition, baseline characteristics, including age, sex, comorbidities, and recent iron supplementation or erythropoietin administration, were evaluated. RESULTS: Our findings revealed an in-hospital mortality rate of 28.6%. The median hospital and ICU stays were 20 and 5 days, respectively, with common comorbidities including hypertension, and diabetes mellitus (DM). Among the patients, the hemoglobin levels of 3967 patients were confirmed at the time of discharge from the ICU, representing 99.95% of the total. The prevalence of anemia persisted post- ICU discharge; less than 30% of patients recovered, whereas 13.6% of them experienced worsening of anemia post-ICU discharge. Factors contributing to anemia severity were female sex, DM, chronic renal failure, malignant solid tumors, and administration of iron supplements. CONCLUSIONS: This study highlighted the need for targeted interventions to manage anemia post-ICU discharge and suggested potential factors that influence recovery from anemia.

Small intestinal adenocarcinoma accompanied by lynch syndrome: A case report.

RATIONALE: Lynch syndrome is caused by germline mutations of DNA mismatch repair genes. A significant risk increase for several types of cancer is one of the characteristics of lynch syndrome. PATIENT CONCERNS: A 45-year-old female presented to the emergency department with abdominal pain that had persisted for a month. DIAGNOSES: The abdominal and pelvic computed tomography scan showed edematous and thickening of the proximal small bowel wall, as well as dilatation of the proximal bowel and stomach. INTERVENTIONS: Tumor resection of the small bowel was performed, and adenocarcinoma was confirmed pathologically. Microsatellite instability was also confirmed. OUTCOMES: Postoperative imaging revealed soft tissue lesions with potential for tumor seeding. Two months after the first surgery, a secondary surgery was performed as a result of cancer recurrence. The patient received chemotherapy with capecitabine. The latest computed tomography scan, performed 19 months after the cessation of chemotherapy, did not show any recurrence. LESSONS: In the rare incidence of small bowel cancer genetic mutation testing and detailed family history should be actively considered.

Secondary hemophagocytic lymphohistiocytosis associated with heat stroke: A case report and review of literature.

RATIONALE: Hemophagocytic lymphohistiocytosis (HLH) is a syndrome with potentially fatal consequences that results from an excessive immune response caused by malfunctioning natural killer cells and cytotoxic T lymphocytes. Secondary HLH, which is the predominant type in adults, is associated with various medical conditions, including infections, malignancies, and autoimmune diseases. Secondary HLH associated with heat stroke has not been reported. PATIENT CONCERNS: A 74-year-old male was admitted to the emergency department after being unconscious in a 42°C hot public bath. The patient was witnessed to be in the water for more than 4 hours. The patient's condition was complicated by rhabdomyolysis and septic shock, which were managed with mechanical ventilation, vasoactive agents, and continuous renal replacement therapy. The patient also showed evidence of diffuse cerebral dysfunction. DIAGNOSES: While the patient's condition initially improved, the patient developed a fever, anemia, thrombocytopenia, and an acute rise in total bilirubin, which, we suspected, was caused by HLH. Further investigations revealed elevated serum ferritin and soluble interleukin-2 receptor levels. INTERVENTIONS: The patient received 2 cycles of serial therapeutic plasma exchange to lower the endotoxin burden. To manage HLH, high-dose glucocorticoid therapy was done. OUTCOMES: Despite the best efforts, the patient did not recover and expired from progressive hepatic failure. LESSONS: We report a novel case of secondary HLH associated with heat stroke. Diagnosing secondary HLH can be difficult since clinical manifestations of the underlying disease and HLH may present simultaneously. Early diagnosis and prompt initiation of treatment is required to improve the prognosis of the disease.

Feasibility of Ultrasound-Guided, Peripherally Inserted Central Catheter Placement at the Bedside in a Communicable-Disease Isolation Unit.

BACKGROUND: Previous studies have investigated the safety of peripherally inserted central catheters (PICCs) in the intensive care unit (ICU). However, it remains uncertain whether PICC placement can be successfully carried out in settings with limited resources and a challenging environment for procedures, such as communicable-disease isolation units (CDIUs). METHODS: This study investigated the safety of PICCs in patients admitted to CDIUs. These researchers used a handheld portable ultrasound device (PUD) to guide venous access and confirmed catheter-tip location with electrocardiography (ECG) or portable chest radiography. RESULTS: Among 74 patients, the basilic vein and the right arm were the most common access site and location, respectively. The incidence of malposition was significantly higher with chest radiography compared to ECG (52.4% vs. 2.0%, p < 0.001). CONCLUSIONS: Using a handheld PUD to place PICCs at the bedside and confirming the tip location with ECG is a feasible option for CDIU patients.

Emergency gastrointestinal tract operation associated with cytomegalovirus infection.

Purpose: Cytomegalovirus (CMV) infection is common in immunocompromised patients. Enterocolitis caused by CMV infection can lead to perforation and bleeding of the gastrointestinal (GI) tract, which requires emergency operation. We investigated the demographics and outcomes of patients who underwent emergency operation for CMV infection of the GI tract. Methods: This retrospective study was conducted between January 2010 and December 2020. Patients who underwent emergency GI operation and were diagnosed with CMV infection through a pathologic examination of the surgical specimen were included. The diagnosis was confirmed using immunohistochemical staining and evaluated by experienced pathologists. Results: A total of 27 patients who underwent operation for CMV infection were included, 18 of whom were male with a median age of 63 years. Twenty-two patients were in an immunocompromised state. Colon (37.0%) and small bowel (37.0%) were the most infected organs. CMV antigenemia testing was performed in 19 patients; 13 of whom showed positive results. The time to diagnose CMV infection from operation and time to start ganciclovir treatment were median of 9 days. The reoperation rate was 22.2% and perforation was the most common cause of reoperation. In-hospital mortality rate was 25.9%. Conclusion: CMV infection in the GI tract causes severe effects, such as hemorrhage or perforation, in immunocompromised patients. When these outcomes are observed in immunocompromised patients, suspicion of CMV infection and further evaluation for CMV detection in tissue specimens is required for proper treatment.

Clinical significance of acute care surgery system as a part of hospital medical emergency team for hospitalized patients.

Purpose: Acute care surgery (ACS) has been practiced in several tertiary hospitals in South Korea since the late 2000s. The medical emergency team (MET) has improved the management of patients with clinical deterioration during hospitalization. This study aimed to identify the clinical effectiveness of collaboration between ACS and MET in hospitalized patients. Methods: This was an observational before-and-after study. Emergency surgical cases of hospitalized patients were included in this study. Patients hospitalized in the Department of Emergency Medicine or Department of Surgery, directly comanaged by ACS were excluded. The primary outcome was in-hospital mortality rate. The secondary outcome was the alarm-to-operation interval, as recorded by a Modified Early Warning Score (MEWS) of >4. Results: In total, 240 patients were included in the analysis (131 in the pre-ACS group and 109 in the post-ACS group). The in-hospital mortality rates in the pre- and post-ACS groups were 17.6% and 22.9%, respectively (P = 0.300). MEWS of >4 within 72 hours was recorded in 62 cases (31 in each group), and the median alarm-to-operation intervals of each group were 11 hours 16 minutes and 6 hours 41 minutes, respectively (P = 0.040). Conclusion: Implementation of the ACS system resulted in faster surgical intervention in hospitalized patients, the need for which was detected early by the MET. The in-hospital mortality rates before and after ACS implementation were not significantly different.

Aspergillus appendicitis complicating chemotherapy of leukemia: A case report and review of the literature.

INTRODUCTION: The diagnosis of primary Aspergillus appendicitis can be missed or delayed because of its rarity. We report our experience of a case of Aspergillus appendicitis complicating chemotherapy of leukemia. PRESENTATION OF CASE: A 48-year-old man who was diagnosed with acute myeloid leukemia developed high fever and epigastric pain two weeks after administration of his fourth consolidation chemotherapy. Right lower quadrant tenderness and rebound tenderness were noticed on physical examination, and the abdomen and pelvis computed tomography suggested acute perforated appendicitis with localized peritonitis. Emergency laparoscopy showed an inflamed appendix, which was resected. Pathology reports revealed invasive aspergillosis in the appendix. The patient recovered after high-dose antifungal therapy, although he required prolonged hospitalization. DISCUSSION: Acute appendicitis is very rarely caused by fungi infection with an overall incidence of up to 1.15 %. Differential diagnosis of fungal appendicitis without pathology report is challenging due to low incidence. CONCLUSION: Isolated Aspergillus appendicitis is a rare disease that can progress without appropriate antifungal therapy even after surgical resection of the appendix. Surgeons should pay attention to pathology reports after appendectomy to avoid missing unusual cases, especially in immunocompromised patients.

Combined hydrocortisone, ascorbic acid, and thiamine therapy for septic shock with complicated intraabdominal infection: before and after cohort study.

PURPOSE: The aim of this study was to assess the efficacy of intravenous hydrocortisone, ascorbic acid, and thiamine (HAT) combination therapy in complicated intraabdominal infection (cIAI) patients with septic shock. METHODS: This was a single-center, retrospective before-after clinical study comparing clinical outcomes of cIAI patients with septic shock treated with HAT in a surgical intensive care unit (ICU). Delta modified sequential organ failure assessment (mSOFA) scores were evaluated to assess recovery of organ dysfunction. Additional outcomes included procalcitonin level change, daily vasopressor dosage, mean number of days free of mechanical ventilation in 28 days, and renal replacement therapy days. RESULTS: The delta mSOFA score (ICU admission mSOFA score minus 7th-day mSOFA score) was significantly higher in the HAT group than in the control group on the 7th day (2.30 vs. -0.90, P = 0.003). The median 7-day change in procalcitonin score was higher in the control group than in the HAT group (5.94 vs. 10.72, P = 0.041). The difference in vasopressor score between the 1st day and the 4th day was significantly higher in the HAT group (17.63 vs. 9.91, P = 0.005). CONCLUSION: In our study of cIAI in patients with septic shock, administration of HAT therapy may improve the recovery from organ dysfunction.

Clinical impact of massive transfusion protocol implementation in non-traumatic patients.

BACKGROUND: Massive transfusion protocol (MTP) has been used to provide plasma and packed red blood cells (pRBCs) rapidly. MTP also has been adapted for non-traumatic patients. The effects of hospital-wide MTP implementation on clinical outcomes were reviewed. METHODS: This was a retrospective study of patients who received massive transfusion before and after MTP implementation, between August 2010 and May 2018. Massive transfusion was defined as 10 or more units of pRBCs within 24 h. Recipients of massive transfusion were divided into periods before and after MTP implementation. The 24 -h death rate, thirty-day death rate and several laboratory findings were investigated. RESULTS: Eighty patients whose massive transfusion occurred before MTP implementation and 63 patients whose massive transfusion occurred after MTP implementation were compared. No statistically significant difference was found in 24 -h death rate (15.0% vs. 23.8%, p = 0.181), or 30-day death rate (43.8% vs. 36.5%, p = 0.381). Use of an anti-fibrinolytic agent was more frequent in patients after the MTP implementation (31.3% vs. 55.6%, p = 0.003). A statistically significant difference was found in the lowest body temperature of the two groups during the 24 -h period (34.7 °C vs. 35.6 °C, p < 0.001). Transfusion ratio of plasma to pRBC was numerically improved after the MTP implementation (1:1.91 vs. 1:1.58, p = 0.173). Earlier initiation of pRBC transfusion was achieved after implementation (51 min vs. 40 min, p = 0.042). CONCLUSIONS: MTP implementation showed improved coagulation profiles, but did not show a statistically significant death-rate reduction in non-traumatic patients.

Treatment Strategies for Cephalic Arch Stenosis in Patients with Brachiocephalic Arteriovenous Fistula.

BACKGROUND: Cephalic arch is one of the sites most susceptible to stenosis in brachiocephalic arteriovenous fistula (BCAVF). We performed a retrospective study to identify the incidence of cephalic arch stenosis (CAS) in BCAVF, to compare the patency of percutaneous transluminal balloon angioplasty (PTA) with that of cephalic vein transposition (CVT), and to establish the optimal treatment strategy for CAS. METHODS: Between January 2011 and June 2016, 462 patients underwent BCAVF creation. CAS was defined as >50% stenosis at the confluence of the cephalic and axillary veins on ultrasonography. Treatment was planned for clinically significant CAS, which was defined as >25% reduction in flow volume compared to previous examination, elevation of venous pressure, delayed puncture site hemostasis, and/or acute thrombotic occlusion. RESULTS: Seventy-seven (16.7%) patients had CAS and 42 of them (54.5%) were treated for clinically significant CAS. PTA was performed in 36 patients (85.7%), and CVT was done in 6 patients (14.3%) as the initial treatment. Nine patients underwent CVT after PTA, resulting in a total of 15 patients treated with CVT. Investigation of the patency of the 36 cases of PTA and 15 cases of CVT revealed that primary-assisted patency rates at 6 and 12 months were 68.2% and 57.3% for PTA and 100.0% and 87.5% for CVT, respectively (P = 0.038). Secondary patency rates at 6 and 12 months were 72.0% and 56.9% for PTA and 100% and 100% for CVT, respectively (P = 0.010). The median intervention rate was 2.5 interventions per access-year in the 36 cases treated with PTA and 1.5 interventions per access-year in the 15 cases treated with CVT. CONCLUSIONS: CAS is a common cause of BCAVF dysfunction, and careful surveillance is warranted. CVT should be considered for treatment of CAS to achieve better long-term patency with fewer reinterventions.

Aorto-carotid bypass in patients with Takayasu arteritis.

PURPOSE: Takayasu arteritis is an indication for bypass surgery when this condition results in severe cerebrovascular ischemia due to occlusion of the carotid arteries. We reviewed the patients with Takayasu arteritis who received aorto-carotid bypass due to cerebrovascular ischemia. METHODS: A retrospective review was performed on 19 patients with Takayasu arteritis who underwent aorto-carotid bypass from March 2002 to April 2015. RESULTS: All patients were female and the mean of their age was 40.6 ± 15.3 years. Eleven patients (57.9%) underwent aorto-uni-carotid bypass and 8 patients (42.1%) underwent aorto-bi-carotid bypass. Five patients (26.3%) whose postoperative blood pressure was not controlled suffered an intracranial hemorrhage within 8 days after bypass surgery. Of the patients with an intracranial hemorrhage, 2 patients (10.5%) expired on 26 days and 7 years after surgery, and 3 patients (15.8%) resolved spontaneously. One patient (5.3%) expired due to an intracranial infarction 9 years after bypass surgery. The intracranial ischemic symptoms resolved after bypass surgery in all of the surviving patients. None of the patients experienced anastomosis site complication postoperatively. CONCLUSION: Aorto-carotid bypass is effective for treating Takayasu arteritis with cerebrovascular ischemia, and the results suggest that postoperative blood pressure should be strictly managed to prevent intracranial hemorrhage.

Editor's Choice - Comparison of Early Outcomes and Restenosis Rate Between Carotid Endarterectomy and Carotid Artery Stenting Using Propensity Score Matching Analysis.

OBJECTIVE/BACKGROUND: Despite randomised evidence, the debate continues about the preferred treatment strategy for carotid stenosis in routine clinical practice. The aim of this study was to compare early outcomes and restenosis rates after carotid endarterectomy (CEA) and carotid stenting (CAS) in unselected patients using propensity score matching (PSM). METHODS: The 30 day incidence of major adverse clinical events (MACE; defined as stroke, transient ischaemic attack, myocardial infarction, or death) and procedure related complications, as well as restenosis rates during follow-up were compared between unselected patients undergoing CEA or CAS between January 2002 and December 2015 at a single institution. PSM was used to balance the following factors between the CEA and CAS cohorts: age, sex, hypertension, diabetes, dyslipidaemia, smoking, atrial fibrillation, previous percutaneous coronary intervention or coronary artery bypass grafting, valvular heart disease, contralateral carotid occlusion, degree of carotid stenosis, and symptomatic status. Statistical comparisons of outcomes were based on logistic regression analysis and log rank test. RESULTS: Of 1184 patients (654 CEA and 530 CAS), 452 PSM pairs of CEA and CAS patients were created. The CAS group showed a relatively higher 30 day incidence of MACE (7.5% vs. 2.4%; odds ratio [OR] 3.261, 95% confidence interval [CI] 1.634-6.509; p = .001) but a lower incidence of procedure related complications (1.5% vs. 5.3%; OR 0.199, 95% CI 0.075-0.528; p = .001). During a mean follow-up of 49.1 months (range 1-180 months), restenosis rates were higher after CAS than after CEA (1.5% vs. 1.0% at 12 months and 5.4% vs. 1.2% at 24 months, respectively; p = .008). CONCLUSION: This PSM based observation reconfirmed previous trial results in both asymptomatic and symptomatic patients with carotid artery stenosis in routine clinical practice: CEA showed lower 30 day MACE and mid-term restenosis rates than CAS.

Compartment Syndrome after Embolization of Arteriovenous Malformation.

Management of arteriovenous malformations (AVMs) remains challenging because of their unpredictable course and high morbidity rate. In this case report, we present a patient with a huge AVM on the right calf who suffered complications of compartment syndrome, rhabdomyolysis, skin necrosis, and nerve damage after sclerotherapy. Limb salvage was achieved in spite of these devastating complications. A multidisciplinary team approach is important especially when making decisions for the management of a complicated AVM.

Lower Extremity Arterial Bypass with Arm Vein Conduits and Literature Review.

PURPOSE: The superiority of autogenous vein conduits is well known in lower extremity arterial bypass (LEAB). Among various alternative conduits for LEAB, long-term results of arm vein grafts were investigated in this study. MATERIALS AND METHODS: We retrospectively reviewed clinical characteristics of 28 patients who underwent infrainguinal LEAB with autogenous arm vein grafts at a single institute between January 2003 and December 2015. All procedures were performed in the absence of adequate saphenous veins. Graft patency was determined by periodic examinations with duplex ultrasonography. RESULTS: Autologous arm vein grafts were implanted for 28 patients (mean age, 60.4±16.8 years; range, 20-82 years; male, 92.9%; atherosclerosis, 19 [67.9%]; and non-atherosclerotic disease 9 [32.1%] including 5 patients with Buerger's disease). Source of arm vein were basilic 13 (46.4%), cephalic 4 (14.3%) and composition graft with other veins in 11 (39.3%) cases. The level of distal anastomosis was distributed as popliteal in 5 (17.9%), tibio-peroneal in 21 (75.0%) and inframalleolar artery in 2 (7.1%) cases. Mean duration of follow-up was 41.5±46.9 months (range, 1-138 months). Cumulative primary patency rates at 1, 3, and 5 years were 66.5%, 60.9% and 60.9%, respectively. Assisted-primary patency rates at 1, 3 and 5 years were 66.5%, 66.5% and 66.5%, respectively. Secondary patency rates at 1, 3 and 5 years were 70.8%, 70.8% and 70.8%, respectively. There was one limb amputation during the follow-up period. CONCLUSION: Arm veins are a useful alternative conduit when great saphenous veins are not available during LEAB.

Factors affecting long-term survival after surgical resection of pancreatic ductal adenocarcinoma.

PURPOSE: Some patients who undergo surgical resection of pancreatic cancer survive longer than other patients. The purpose of this study was to identify the factors that affect long-term survival after resection of histopathologically confirmed pancreatic ductal adenocarcinoma. METHODS: A single-center, retrospective study was conducted among 164 patients who underwent surgical resection of pancreatic cancer, between May 1995 and December 2004. The patient follow-up process was conducted via telephone survey and review of electronic medical records for at least 5 years or until death. RESULTS: We compared patients with long-term (≥60 months, n = 19) and short-term survival (<60 months, n = 145). Resection margin status, differentiation of the tumor, tumor stage, pre-operative serum level of albumin, total bilirubin and carbohydrate antigen (CA) 19-9 level are related with survival difference (all factors, P < 0.05). Multivariate analysis revealed that a pre-operative serum total bilirubin level <7 mg/dL and a pre-operative serum CA19-9 level <37 U/mL is a statistically significant prognostic factor for long-term survival. CONCLUSION: The preoperative serum total bilirubin and serum CA19-9 levels are associated with long-term survival after surgical resection of pancreatic cancer.

A case of recurrent infection caused by a pancreaticoduodenal fistula associated with a pancreatic arteriovenous malformation.

Although arteriovenous malformations (AVM) occur frequently in digestive organs, pancreatic AVM is rare. The clinical symptoms of pancreatic AVM are variable and include gastrointestinal bleeding, abdominal pain, jaundice, portal hypertension, pancreatitis, and duodenal ulcer. However, choledochoduodenal or pancreaticoduodenal fistulas complicated with ascending infection and pancreatitis is extremely rare. Herein, we report a case of pancreaticoduodenal fistula associated with a pancreatic AVM that induced recurrent anemia and ascending infection.

Usefulness of cap-assisted colonoscopy during colonoscopic EMR: a randomized, controlled trial.

BACKGROUND: Clinical demand for total colonoscopy is increasing. Several articles have reported on the usefulness of a cap for faster cecal intubation and reduced patient discomfort, but results for polyp and adenoma detection have been inconsistent. OBJECTIVE: To assess the efficacy of a cap attached to the tip of a colonoscope for detection and resection of polyps by experienced colonoscopists. DESIGN: Prospective, randomized, controlled trial. SETTING: A tertiary referral center. PATIENTS AND INTERVENTION: A total of 329 patients who underwent colonoscopic EMR were randomized to cap-assisted colonoscopy (CAC) (CAC group, n = 166) or regular colonoscopy (RC) (RC group, n = 163). MAIN OUTCOME MEASUREMENTS: Cecal intubation time, total procedure time, required time for colonoscopic EMR of each polyp, and missing polyp rate. RESULTS: The cecal intubation time in the CAC group and RC group was 5.3 ± 3.3 minutes and 5.8 ± 3.7 minutes, respectively (P = .170). The total procedure time in the CAC group and RC group was 23.0 ± 15.5 minutes and 29.2 ± 13.4 minutes, respectively (P = .626). The time required for colonoscopic EMR of each polyp in the CAC group and RC group was 3.5 ± 4.5 minutes and 4.2 ± 5.1 minutes, respectively (P = .010). The number of polyps during the initial colonoscopy in the CAC group and RC group was 2.2 ± 1.7 and 2.0 ± 1.8, respectively (P = .221). The number of detected polyps during colonoscopic EMR in the CAC group and RC group was 3.4 ± 2.7 and 2.7 ± 1.9 (P = .003). The number of missed polyps in the CAC group and RC group was 1.1 ± 1.5 and 0.8 ± 0.9 (P = .024). LIMITATION: Single-center experience. CONCLUSIONS: CAC may reduce the time required for colonoscopic EMR of each polyp and may also improve the polyp detection rate.

[A case of lower gastrointestinal bleeding caused by primary iliac arterio-colic fistula].

Arterio-enteric fistula is a very rare cause of massive lower gastrointestinal hemorrhage. We report here on a case of massive hematochezia caused by iliac arterio-colic fistula in a 60-year-old woman who had a recent history of spinal surgery for herniated nucleus pulposus. Abdomen computed tomography showed the extravasation of radiocontrast media from right iliac artery encased by an intraabdominal abscess into the adjacent dilatated colon. Also, diagnostic angiography revealed the active extravasation of radiocontrast media via a fistula between right iliac artery and colon. Although successful endovascular exclusion of the fistula with stent graft and coils was performed, disseminated intravascular coagulation and multi-organ failure were developed.

Establishment of an HBsAg mixed titer performance panel and HBsAg working standard for quality control of HBsAg diagnostic kits in Korea.

BACKGROUND: International Standards or commercial panels used for performance validation of diagnostic kits might not reflect the viral characteristics common in Korea. Also, continuous use of these materials is difficult because of limited quantity and high cost. OBJECTIVES: Establishment of HBsAg reference materials to be used as National Standards for validation of HBsAg diagnostic kits. STUDY DESIGN: 568 plasma units with OD less than 2.0 on HBsAg EIA were collected. HBsAg testing with 3 EIAs and 1 CIA was performed on all units. HBsAg positive units were subjected to HBV DNA quantification, genotyping and subtyping. Candidates for the mixed titer performance panel and working standard were confirmed for HBsAg by neutralization. A collaborative study was conducted for the candidates of the mixed titer performance panel and the working standard. RESULTS: Based on the results of the collaborative study, a working standard (KFDA08/024) consisting of a series of four-fold dilutions of 2 materials, one with genotype/subtype C2/adr and the other with C1/adw, was established. A mixed titer performance panel composed of 2 negative and 16 positive samples was also established. A G1896A and a T/I126S mutant are included in the positive samples. CONCLUSIONS: An HBsAg mixed titer performance panel and a working standard reflecting HBV genotypes/subtypes prevalent in Korea have been established as National Standards. This will enable consistent supply of validation materials, improve the validation system of HBsAg diagnostic kits in Korea and lead to quality improvement of diagnostic kits.