Brief Communication

Ann Lab Med 2021; 41(2): 230-239

Published online March 1, 2021

Copyright © Korean Society for Laboratory Medicine.

Schemes and Performance Evaluation Criteria of Korean Association of External Quality Assessment (KEQAS) for Improving Laboratory Testing

Sollip Kim, M.D., Ph.D.1 , Kyunghoon Lee, M.D., Ph.D.2 , Hyung-Doo Park, M.D., Ph.D.3 , Yong-Wha Lee, M.D., Ph.D.4 , Sail Chun, M.D., Ph.D.5 , and Won-Ki Min, M.D., Ph.D.5

1Department of Laboratory Medicine, Inje University, Ilsan Paik Hospital, Goyang, Korea; 2Department of Laboratory Medicine, Seoul National University Bundang Hospital and College of Medicine, Seongnam, Korea; 3Department of Laboratory Medicine and Genetics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea; 4Department of Laboratory Medicine and Genetics, Soonchunhyang University Bucheon Hospital, Soonchunhyang University College of Medicine, Bucheon, Korea; 5Department of Laboratory Medicine, University of Ulsan College of Medicine and Asan Medical Center, Seoul, Korea

Correspondence to: Sail Chun, M.D., Ph.D.
Department of Laboratory Medicine, University of Ulsan College of Medicine and Asan Medical Center, 88 Olympic-ro 43-gil, Songpa-gu, Seoul 05505, Korea
Tel: +82-2-3010-4513
Fax: +82-2-478-0884

Received: March 17, 2020; Revised: June 7, 2020; Accepted: September 19, 2020

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License ( which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

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.

Keywords: Korean Association of External Quality Assessment Service (KEQAS), Performance, Evaluation, Laboratory testing, Schemes, Quality, Harmonization

External quality assessment (EQA) is a widely accepted method for evaluating clinical laboratories and enhancing their testing quality [1]. EQA helps laboratories recognize and resolve their deficiencies in routine processes while instilling employee confidence [2]. All laboratories should therefore be encouraged to participate in EQA schemes, and such participation should be mandatory wherever possible [3]. Effective participation in EQA schemes in Europe is a mandatory requirement for country-specific accreditation bodies to have access to International Standards Organization (ISO) 15189 accreditation [4, 5]. In the United States, laboratories that conduct moderate or high-complexity tests are subject to reported inspections on a biennial basis and should participate in an EQA scheme authorized by the Center for Medicare & Medicaid Services under the Clinical Laboratory Improvement Amendment Law, which applies to all laboratories testing human specimens [6]. In Korea, laboratories with a satisfactory EQA can receive a quality incentive for testing since the notification of the Ministry of Health and Welfare took effect in 2017 [7]. However, EQA participation is not yet mandatory for laboratories in Korea, except for referral laboratories, and even basic data such as the adequacy of EQA schemes are not available. Since many EQA schemes vary broadly in terms of content, it is crucial that the EQA organizers share their experiences to continuously improve the EQA scheme. We provide an overview of the EQA schemes and performance evaluation criteria of the Korean Association of External Quality Assessment Service (KEQAS) and suggest directions for joining global harmonization movements.

The KEQAS has been the leading authorized EQA institute for the standardization and quality management of clinical laboratories in Korea since 1976. Although the number of KEQAS programs is relatively small compared with other major EQAs, all the most requested routine tests, except special tests performed only at some university hospitals, are covered by the existing programs. The KEQAS obtained ISO 17043 (EQA provider) accreditation in August 2015. Major changes to the EQA schemes were implemented in 2016; the assessment is now fully computerized to accelerate feedback, and the methods of analysis and reporting across schemes are unified [8] (Table 1). Since these changes, the number of programs has increased significantly from 46 in 2016 and 65 in 2019 to 70 in 2020. These programs cover all disciplines of laboratory medicine, including three programs of accuracy-based proficiency tests, two of point-of-care tests, one of liquid biopsy, and three of next-generation sequencing, with a total of 852 test items covered and 1,844 institutions participating in EQA as of February 2020. Approximately 50% of hospitals (including small-to-medium sized hospitals, general hospitals, and tertiary care hospitals) that submit health insurance claims for laboratory tests in Korea participate in the KEQAS EQA [9]. Currently, specimens for 50 programs are prepared inhouse, whereas specimens for the remaining programs are purchased from third-party manufacturers. With respect to the transport time after specimen shipments (e.g., the sixth shipment of 2019), 90% of the participating laboratories received the specimens within 32 hours and 99.9% within 48 hours. EQA results may be influenced by the deterioration of specimens during transportation and storage before testing [10]. Many specimens should be transported refrigerated or frozen; therefore, it is advantageous to deliver the specimens as soon as possible.

Table 1 . Overview of the proficiency test scheme of the Korean Association of External Quality Assessment Service

DisciplineClassification of the ProgramProgramTestsDistribution/yrSpecimen (origin; type; state; preparation)Shipping conditions (°C)N participants (2020)
Transfusion medicinePretransfusion testingBlood crossmatching and Blood typing, generalBlood crossmatching; ABO typing; RhD typing2Human; WB; Liquid; IHFRG923
Blood typing, specialABO subtyping; Rh CcEe Ag test; Weak D test2Human; WB; Liquid; IHFRG253
Transfusion Ab, generalUnexpected Ab, screening; Direct anti-human globulin test2Human; WB and plasma; Liquid; IHFRG335
Transfusion Ab, specialUnexpected Ab, identification; ABO Ab titration2Human; Plasma; Liquid; IHFRG139
Diagnostic hematologyHematology and clinical microscopyCBC and microscopyCBC2Animal; WB; Liquid; PFRG1,819
Blood cell morphology2Human; Blood smear; Image; IH
Peripheral blood smear (pilot project)Malaria detection; Parasitemia; Identification2Human; Blood smear; Image; IH277
ESR (pilot project)ESR2Synthetic material; Latex; Liquid; PFRG448
Human; WB; Liquid; PFRG
CoagulationCoagulation, generalPT INR; aPTT; Coagulation factor I (fibrinogen); Thrombin time; Antithrombin III activity2Human; Plasma; Lyophilized; PFRG606
Coagulation, specialProtein C (functional); Protein S (functional)2Human; Plasma; Lyophilized; PFRG20
Clinical chemistryUrinalysis and stool occult blood, etc.UrinalysisUrinalysis3Animal; Serum, Hb and Enzyme; Liquid; PFRG1,726
Urine sediment3Human; Urine; Image; IH
Stool occult bloodStool occult blood (QL); Stool occult blood (QN)2Other origins; Hb; Lyophilized; PFRG1,014
Blood gas analysisBlood gas analysispH; pCO2; pO2; Lactic acid; Ionized calcium; Ionized magnesium; Sodium; Potassium; Chloride2DW; Buffered bicarbonate and electrolyte solution; Liquid; PFRG420
Blood gas analysis, POCTpH; pCO2; pO22DW; Buffered bicarbonate and electrolyte solution; Liquid; PFRG177
General chemistryRoutine chemistrySodium; Potassium; Chloride; Calcium; Phosphorus; Magnesium; BUN; Glucose; Cholesterol; HDL-C; LDL-C; TG; ALT; ALP; AST; Bilirubin, total; Bilirubin, direct; Albumin; Protein; GGT; LDH; Amylase; Lipase; CK; Uric acid; Iron; TIBC; Total CO2; Osmolality4Human; Serum; Lyophilized; PFRG1,801
ICG testICG concentration; K; R152Human; plasma; LiquidFRG40
Urine chemistryUrine albumin; Calcium; Chloride; Creatinine; Glucose; Magnesium; Phosphorus; Potassium; Urine protein; Sodium; Urea Nitrogen; Uric acid; hCG2Human; Urine; Lyophilized; PFRG304
Special proteinsSpecial proteinsCeruloplasmin; Ferritin; Transferrin; Haptoglobin; Prealbumin; Alpha1-antitrypsin; CRP (QL); CRP (QN); ASO (QL); ASO (QN); RF (QL); RF (QN)2Human; Serum; Liquid; PF620
Carbohydrates, lipids, proteins, and vitaminsGlucose, POCTGlucoseHuman; Serum and Hb; Liquid; PFRG375
Cardiac markersCK-MB, mass; CK-MB, activity; Homocysteine; Myoglobin; Troponin I; Troponin T; BNP; Pro-BNP; High sensitivity CRP2Human; Serum; Liquid; IHF475
Metabolism testingNewborn screeningTotal galactose; 17-hydroxyprogesterone; TSH; T4, total; Newborn screening for inborn error of metabolism2Human; WB; Dried blood spot; IHF17
Organic acid profileOrganic acid profile2Human; Urine; Liquid; IHF5
Amino acid profileAmino acid profile2Human; Plasma; Liquid; IHF7
Special metabolitesMethylmanonic acid; Vanillylmandelic acid; Epinephrine, urine; Norepinephrine, urine; Dopamine, urine; Metanephrine, urine; Normetanephrine, urine; Epinephrine, plasma; Norepinephrine, plasma; Dopamine, plasma; Metanephrine, plasma; Normetanephrine, plasma2Human; Urine and plasma; Liquid; IHF10
EndocrinologyHormones ITSH; T4, total; T4, free; T3, total; Thyroglobulin; hCG, total (serum); Testosterone; Estradiol; Progesterone; Prolactin; Insulin; Folate; Human growth hormone; Vitamin B12; Cortisol2Human; Serum; Liquid; PF661
Hormones IIPTH; Erythropoietin; Vitamin D; Procalcitonin2Human; Serum; Lyophilized; PFRG315
Hormones III (pilot project)Anti-Mullerian hormone2Human; Serum; LiquidF31
Tumor markersTumor markers IAFP (QN); CEA; PSA; PIVKA-II2Human; Serum; Liquid; IHF723
Tumor markers IICA 125; CA 19-9; CA 15-3; CA 72-4; Beta2-microglobulin; Human epididymis protein 42Human; Serum; Lyophilized; PFRG446
Therapeutic drug monitoring and toxicologyTherapeutic drug monitoring, generalAcetaminophen; Amikacin; Amitriptyline; Carbamazepine; Carbamazepine,free; Chloramphenicol; Desipramine; Disopyramide; Digoxin; Ethosuximide; Lidocaine; Gentamicin; Lithium; Methotrexate; Nortriptyline; Phenobarbital; Phenytoin; Phenytoin, free; Primidone; Procainamide; Propranolol; Quinidine; Salicylate; Theophylline; Tobramycin; Valproic acid; Valproic acid, free; Vancomycin2Human; Serum; Lyophilized; PFRG106
Immunosuppressants therapeutic drug monitoringCyclosporine; Tacrolimus (FK506); Sirolimus; Everolimus2Human; WB; Liquid; PFRG13
Therapeutic drug monitoring, specialMPA; Voriconazole; Posaconazole; Itraconazole2Human; Serum; Liquid; IHFRG77
Drug of abuse (QL)Amphetamine; Methamphetamine; MDMA; Morphine, Free; Phencyclidine; 3,4-Secobarbital; 9-COOH-11-nor-Δ9-THC; Benzoylecgonine; Ethanol; LSD; Methadone; Methaqualone; Nordiazepam; Nortriptyline; Oxazepam; Propoxyphene2Human; Urine; Liquid; PFRG141
Accuracy-based chemistryAccuracy-based lipidsCholesterol, total; HDL-C; LDL-C; TG; Apolipoprotein A1; Apolipoprotein B; Lipoprotein(a)2Human; Serum; Liquid; IHF275
Accuracy-based creatinineCreatinine; estimated GFR2Human; Plasma; Liquid; IHF1,758
Accuracy-cased HbA1cHbA1c2Human; WB; Liquid; IHFRG597
Diagnostic immunologyComplements and immunoglobulinsComplements and immunoglobulinsC3; C4; IgG; IgA; IgM; IgE; FLC, kappa; FLC, lambda2Human; Serum; Liquid; PF164
SerologySyphilis testsNon-treponemal test; Treponemal test2Human; Plasma; Liquid; IHF595
Hepatitis serologyHBsAg; HBsAb; HCV Ab; HBcAb, total; HBc Ab, IgM; HBeAg; HBeAb; HAV Ab, total; HAV Ab, IgG; HAV Ab, IgM2Human; Plasma; Liquid; IHF1,103
Virus serology IHIV Ag/Ab; HTLV Ab; CMV Ab, IgG; CMV Ab, IgM2Human and Animal; Serum; Liquid; IHF591
Virus serology IIRubella IgG; Rubella IgM; EBV Viral Capsid Ag, IgG; EBV Viral Capsid Ag, IgM; EBV Nucleic Acid Ag, IgG2Human and Animal; Serum; Liquid; IHF93
Histocompatibility testingHLA typingHLA Typing2Human; WB; Liquid; IHFRG69
HLA typing, specialHLA B27 Typing; HLA B51 Typing2Human; WB; Liquid; IHFRG62
HLA crossmatchingHLA crossmatching, CDC; HLA crossmatching, flow cytometry2Human; Serum and PBMC; Liquid; IHRT (PBMC) and FRG (serum)48
HLA Ab testsHLA Ab screening; HLA Ab identification2Human; Serum; Liquid; IHFRG26
Cellular immunity, flow cytometryLymphocyte subset assayLymphocyte subset assay2Human; WB; Liquid; IHRT56
Stem/progenitor cell assayCD34+Stem/Progenitor cell assay2Human; WB; Liquid; IHRT42
Hematologic malignancy immunophenotypingHematologic malignancy immunophenotyping2Human; WB and BM aspirate; Liquid; IHRT44
AutoimmunityAutoimmune Assay IANA; Anti-mitochondrial Ab; Anti-smooth muscle Ab2Human; Serum; Liquid; IHF82
Autoimmune Assay IIAnti-thyroglobulin Ab; Anti-thyroperoxidase Ab; Anti-dsDNA Ab2Human; Serum; Liquid; IHF111
Allergy testAllergy testAllergen-specific IgE (QN), Multi-allergen screen (Semi-QN)2Human; Serum; Liquid; IHF121
Infection-induced immune responsesTuberculosis Ag responseIGRA2Animal; Serum and Interferon-gamma power; Lyophilized; IHFRG76
Clinical microbiologyMicrobiologyMycobacteriology, generalAcid-fast stain microscopy3Human; MTB; Slide; IHFRG255
Acid fast bacilli culture; Acid fast bacilli identification3Human; Sputum; Liquid; IHFRG
Mycobacteriology, drug sensitivityAcid-fast bacilli antibiotic sensitivity3Human; MTB; Liquid; IHFRG7
BacteriologyBacteria stain microscopy; Bacteria culture; Bacteria identification; Antibiotics sensitivity test3Human; Bacteria; Liquid medium; IHFRG282
MycologyFungus stain microscopy; Fungus culture; Fungus identification2Human; Fungus; Liquid medium; IHFRG135
ParasitologyParasite eggs image3Human and Animal; Parasite egg; Image; IHFRG217
Parasite eggs slide3Human and Animal; Parasite egg; Slide; IHFRG
Molecular diagnosticsMolecular microbiologyMolecular microbiology, mycobacteriaMTB DNA; MTB DNA, isoniazid resistance mutation; MTB DNA, rifampicin resistance mutation3Human; MTB and NTM; Liquid; IHFRG132
Molecular microbiology, hepatitis virusesHBV (QL); HBV (QN); HCV (QL); HCV (QN); HBV DNA drug resistance mutation2Human; Plasma; Liquid; IHF121
Molecular microbiology, virusesCMV (QL); CMV (QN); EBV (QL); EBV (QN); HPV (QL); HIV (QL); HIV (QN); Adenovirus (QL); Influenzavirus A,B (QL); Parainfluenza 1,2,3 virus (QL); RSV (QL), BK virus (QL)2Human; Serum (Plasma); Liquid; IHF124
2Human; Virus; Liquid; IHF
Human geneticsCytogeneticsChromosomal analysis3Human; WB; Image; IH-40
FISHFluorescence in situ hybridization3Human; WB; Slide; IHF32
Molecular, hematologic malignancyLeukemia gene rearrangement; JAK2 gene V617F mutation; FLT3 gene internal tandem duplication; FLT3 gene tyrosine kinase domain mutation; NPM1 gene mutation, CALR gene mutation2Human; WB; Liquid (DNA); IHFRG48
Molecular, solid tumorsKRAS gene mutation; EGFR gene mutation; BRAF gene mutation; KIT (C-Kit) gene mutation2Human; DNA; Liquid; IHFRG28
Molecular, genetic disordersBRCA1; BRCA2; TP53; ATP7B; MT-TL1; MT-TK; GJB2; LHON major mutation; RET; Spinocerebellar ataxia; APOE genotyping; FGFR3 major mutation; MTHFR genotyping; Prader-Willi/Angelman syndrome; DMD, Del/Dup; HD gene trinucleotide repeat expansion; FMR1 gene trinucleotide repeat expansion; TGFBI major mutation; SBMA; SMN1, Del/Dup2Human; DNA; Liquid; IHFRG56
Pharmacogenetics, Molecular, pharmacogeneticsCYP2C19 genotyping; CYP2C9 genotyping; VKORC1 genotyping; CYP2D6 genotyping; TPMT genotyping2Human; DNA; Liquid; IHFRG21
Human genetics, others Molecular, othersABO genotyping2Human; DNA; Liquid; IHFRG16
Liquid biopsyEGFR gene2Human; Plasma; Liquid; IHF30
NGS, somaticNGS - somatic2Human; DNA; Liquid and FASTQ file; IHF23
NGS, germlineNGS - germline2Human; DNA; Liquid and FASTQ file; IHF24
NGS, liquid biopsy (pilot project)NGS - liquid biopsy2Human; DNA; LiquidF5

Abbreviations: Ab, antibody; AFP, alpha-fetoprotein; Ag, antigen; ALP, alkaline phosphatase; ALT, alanine transferase; ANA, anti-nuclear Ab; aPTT, activated partial thromboplastin time; ASO, anti-streptolysin O; AST, aspartate aminotransferase; BNP, brain natriuretic peptide; BUN, blood urea nitrogen; C, complement component; CA, cancer antigen; CBC, complete blood cell count; CDC, complement-dependent cytotoxicity; CEA, carcinoembryonic Ag; CK, creatine kinase; CK-MB, creatine kinase-MB; CMV, cytomegalovirus; CRP, C-reactive protein; EBV, Epstein-Barr virus; estimated GFR, estimated glomerular filtration rate; F, frozen; FISH, fluorescence in situ hybridization; FLC, free light chain; FRG, refrigerated; GGT, gamma-glutamyl transferase; HAV, hepatitis A virus; Hb, hemoglobin; HbA1c, hemoglobin A1c; HBcAb, hepatitis B virus core Ab; HBeAb hepatitis B virus envelope Ab; HBeAg, hepatitis B virus envelope Ag; HBsAb, hepatitis B virus surface Ab; HBsAg, hepatitis B virus surface Ag; hCG, human chorionic gonadotropin; HCV, hepatitis C virus; HDL-C, high-density lipoprotein cholesterol; HIV, human immunodeficiency virus; HLA, human leukocyte antigen; HPV, human papillomavirus; HTLV, human T-lymphotropic virus; ICG, indocyanine green; Ig, immunoglobulin; IGRA, interferon-gamma release assay; IH, in-house prepared quality material; LDH, lactate dehydrogenase; LDL-C, low-density lipoprotein cholesterol; LSD, lysergic acid diethylamide; MDMA, methylene dioxy methamphetamine; MPA, methiopropamine; NGS, next-generation sequencing; P, purchased quality material; PBMC, peripheral blood mononuclear cell; PIVKA-II, protein induced by vitamin K absence or antagonist-II; POCT, point-of-care testing; PSA, prostate-specific antigen; PT, prothrombin time; PTH, parathyroid hormone; QL, qualitative; QN, quantitative; RF, rheumatoid factor; RSV, respiratory syncytial virus; RT, room temperature; T3, triiodothyronine; T4, thyroxine; TG, triglyceride; TIBC, total iron-binding capacity; TSH, thyroid-stimulating hormone; WB, whole blood.

Accuracy-based EQA, which refers to commutable materials with target values, has substantially contributed to improving the accuracy of clinical laboratory tests [10]. The KEQAS has provided accuracy-based EQA for HbA1c tests since 2009, and for five chemistry tests (cholesterol, HDL cholesterol, LDL cholesterol, triglyceride, and creatinine) since 2011 [11]. The number of participants in accuracy-based EQA for HbA1c and creatinine in 2020 was 597 and 1,758, respectively. In 2011, Miller and colleagues [10] suggested six categories of EQA based on specimen characteristics, including commutability, value assignment method, and replication in the EQA survey. For example, programs in category 1 use commutable specimens with target values established by a reference system, and programs in category 2 are the same as those of category 1, except that specimens are not replicated within the survey cycle. Programs in categories 3 and 4 use commutable specimens, but the target values are not assigned by a reference system. Programs in categories 5 and 6 use non-commutable specimens [10]. Accuracy-based EQA in the KEQAS belongs to category 2, whereas the other KEQAS programs belong to category 6. The KEQAS should not only continue to increase its accuracy-based programs, but should also attempt category 1 EQA, which allows for evaluations of imprecision in laboratories by conducting repeated tests.

The consensus value of a peer group is the basis of a laboratory’s evaluation by the KEQAS EQA scheme. A peer group usually consists of laboratories that use the same analyzer from the same manufacturer, as similar matrix-related bias for a given specimen can be assumed. The use of manufacturer-based peer groups is the only acceptable method for comparing the test results of multiple analytes in immunoassay, hematology, and molecular test schemes, which lack standardization and/or harmonization across participating laboratories that use similar principles but slightly different methodologies [12]. The peer groups are further divided into instrumentor reagent-based subgroups. However, for general chemistry, the peer group is based on those using the same methods, not on the same manufacturer, because many laboratories use an open system with regards to the manufacturers of instruments, calibrators, and reagents. The peer groups are further divided into reagent manufacturer-based subgroups. The KEQAS evaluates the participants’ results based on the standard deviation index (SDI) among peer groups for quantitative tests, which is calculated as the difference between the individual laboratory test results and the mean result of the peer group divided by the peer group SD. Therefore, the SDI reflects bias as a multiple of the SD. The SDI is evaluated when the peer group size (i.e., the number of participants in each category) is eight or larger after removing outliers. In such cases, the subgroups are also evaluated. SDI > 3 is considered unacceptable.

Currently, there are large differences in the analytical performance specifications (APS) used in different EQA schemes [13]. Maximum tolerance limits can be statistically determined (e.g., using ± 3 SDIs or Z-scores) or established as fixed percentages or amounts (e.g., ± 15% of the target value or ± 10 mg/dL) [14]. As the SDI is a standardized value, it can be compared among all analytes [15]. However, the limitation of the statistical method is that when applying the SDI as a tolerance limit, the acceptable range for peer groups with larger SDs is larger than that for peer groups with smaller SDs. Quantitative responses of the US College of American Pathologists (CAP) EQA scheme are evaluated based on a fixed range, mean percentage, SD, or variable range according to the test items. Switzerland’s Suisse de Contrôle de Qualité uses government regulations and a combination of limits established by scientific societies and Z-scores to determine the acceptable range. The Netherlands’ Dutch Foundation for Quality Assessment in Medical Laboratorie (SKML) and the UK Welsh EQA provider (WEQAS) use a combination of biological variation and state-of-the-art methods [13]. Although the KEQAS has been using the SDI as a tolerance limit for evaluation, APS should be considered as an alternative based on the clinical requirement for each test.

Peer groups of qualitative tests are formed in the same manner, that is, according to the same instrument manufacturer and the same reagent manufacturer with respect to the characteristics of the tests. Flow diagrams of performance evaluation for qualitative and semi-quantitative tests are shown in Fig. 1A and B, respectively.

Figure 1. Flow diagram of performance evaluation for (A) qualitative and (B) semi-quantitative tests in the KEQAS EQA scheme. Abbreviations: KEQAS, Korean Association of External Quality Assessment Service; EQA, external quality assessment.

The performance evaluation for qualitative and semi-quantitative tests has not yet been standardized [13]. For qualitative tests, 80% consensus of referees or participants is the standard used for evaluation in the US CAP EQA scheme; for example, in urinalysis dipstick tests, 80% participant consensus can be determined by grouping the mode with the next one or the two most frequent responses. In the EQA scheme of the UK WEQAS, the spiked values are used to determine the target value; if these values are not available, interpretation is based on the majority percentage of responses from participants. In the EQA scheme of SKML, performance is scored using a point system based on expert findings or consensus results. However, detailed information on the evaluation criteria of these EQA schemes are not available. The KEQAS’s new suggestions for performance criteria for qualitative and semi-quantitative tests based on experience will be useful for achieving global EQA harmonization.

Two reports (the participant evaluation report and participants’ summary) are electronically generated simultaneously within five working days after each participant submit its results for each round of the scheme (Fig. 2). The mean turnaround time from result submission to report release was 33 days (range 6–104 days) in 2019 because of the review by the program manager. One of the drawbacks of EQAs is that laboratories cannot obtain feedback in a timely manner [6]. Therefore, KEQAS should consider ways to shorten the time for the review. For example, the evaluation criteria should be well established, there should be measures in place to cope with exceptions, and the assessment should be fully automated.

Figure 2. Examples of the EQA reports of the KEQAS. (A) Participant evaluation report and (B) participants’ summary. Abbreviations: KEQAS, Korean Association of External Quality Assessment Service; EQA, external quality assessment.

Approximately 60%–70% of the laboratory tests errors are due to the pre-analytical process [16]. Therefore, identifying appropriate quality metrics is crucial in determining the quality of laboratory services [17]. According to the model of quality indicators developed by the Working Group of the International Federation of Clinical Chemistry and Laboratory Medicine [17], proficiency testing and EQA schemes have allowed clinical laboratories to measure, monitor, and improve their analytical performance over time [18-20]. It may be helpful to introduce extraanalytical quality indicators in the KEQAS EQA scheme to monitor and improve the overall quality of more laboratories.

In conclusion, the KEQAS has been providing the EQA scheme for 45 years to improve the quality of clinical laboratories in Korea. Our summary of the EQA scheme, performance evaluation criteria of the KEQAS, and suggestions for improvement would help achieve global harmonization of EQA.

SC and WKM designed the study; SK and KL collected data and wrote manuscript; and HDP and WHL edited the manuscript. All authors have read and approved the final manuscript.

This study was supported by the research fund of the Korean Association of External Quality Assessment Service (Fund No. KEQAS-2019-01).

  1. Jang MA, Yoon YA, Song J, Kim JH, Min WK, Lee JS, et al. Effect of accreditation on accuracy of diagnostic in medical laboratories. Ann Lab Med 2017;37:213-22.
    Pubmed KoreaMed CrossRef
  2. Lee W, Ryoo N, Suh HS, Jeon CH. Improvement in external quality assessment results for qualitative fecal immunochemical tests in Korea after feedback to manufacturers. Ann Lab Med 2019;39:584-6.
    Pubmed KoreaMed CrossRef
  3. World Health Organization. WHO manual for organizing a national external quality assessment programme for health laboratories and other testing sites. Geneva, Switzerland: WHO Press, 2016.
  4. Ceriotti F, Cobbaert C. Harmonization of External Quality Assessment Schemes and their role-clinical chemistry and beyond. Clin Chem Lab Med 2018;56:1587-90.
    Pubmed CrossRef
  5. Haliassos A. Inter-laboratory comparisons and EQA in the Mediterranean area. EJIFCC 2018;29:253-8.
  6. Peterson JC, Hill RH, Black RS, Winkelman J, Tholen D. Review of proficiency testing services for clinical laboratories in the United States–final report of a Technical Working Group. Battelle Memorial Institute. Atlanta, GA, 2008.
  7. Kim S, Yun YM, Kim H, Um TH, Chang J, Jeong H, et al. The new diagnosis-related group reimbursement system and laboratory test quality in Korea: analysis of external quality assessment results. Healthcare (Basel) 2020;8:127.
    Pubmed KoreaMed CrossRef
  8. Korean Association of External Quality Assessment Service. (Updated on Sep 2020).
  9. Kim H, Kim S, Yun YM, Um TH, Chang J, Lee KS, et al. Status of quality control for laboratory tests of medical institutions in Korea: analysis of 10 years of data on external quality assessment participation. Healthcare (Basel) 2020;8:75.
    Pubmed KoreaMed CrossRef
  10. Miller WG, Jones GR, Horowitz GL, Weykamp C. Proficiency testing/external quality assessment: current challenges and future directions. Clin Chem 2011;57:1670-80.
    Pubmed CrossRef
  11. Jeong TD, Lee HA, Lee K, Yun YM. Accuracy-based proficiency testing of creatinine measurement: 7 years' experience in Korea. J Lab Med Qual Assur 2019;41:13-23.
  12. Krleza JL, Celap I, Tanaskovic JV. External Quality Assessment in Croatia: problems, challenges, and specific circumstances. Biochem Med (Zagreb) 2017;27:86-92.
    Pubmed KoreaMed CrossRef
  13. Jones GRD, Albarede S, Kesseler D, MacKenzie F, Mammen J, Pedersen M, et al. Analytical performance specifications for external quality assessment-definitions and descriptions. Clin Chem Lab Med 2017;55:949-55.
    Pubmed CrossRef
  14. CLSI. Using proficiency testing and alternative assessment to improve medical laboratory quality. 3rd ed. CLSI QMS24. Wayne, PA: Clinical and Laboratory Standards Institute. 2016.
  15. Coucke W, Soumali MR. Demystifying EQA statistics and reports. Biochem Med (Zagreb) 2017;27:37-48.
    Pubmed KoreaMed CrossRef
  16. Lippi G, Chance JJ, Church S, Dazzi P, Fontana R, Giavarina D, et al. Preanalytical quality improvement: from dream to reality. Clin Chem Lab Med 2011;49:1113-26.
    Pubmed CrossRef
  17. Plebani M, Sciacovelli L, Aita A, Padoan A, Chiozza ML. Quality indicators to detect pre-analytical errors in laboratory testing. Clin Chim Acta 2014;432:44-8.
    Pubmed CrossRef
  18. Duan M, Kang F, Zhao H, Wang W, Du Y, He F, et al. Analysis and evaluation of the external quality assessment results of quality indicators in laboratory medicine all over China from 2015 to 2018. Clin Chem Lab Med 2019;57:812-21.
    Pubmed CrossRef
  19. Badrick T, Gay S, McCaughey EJ, Georgiou A. External Quality Assessment beyond the analytical phase: an Australian perspective. Biochem Med (Zagreb) 2017;27:73-80.
    Pubmed KoreaMed CrossRef
  20. Bachner P. Anniversary of Q-Probes and Q-Tracks quality assurance programs. Arch Pathol Lab Med 2014;138:1139-40.
    Pubmed CrossRef