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https://doi.org/10.11613/BM.2018.020702

National survey on internal quality control for tumour markers in clinical laboratories in China

Wei Wang ; National Center for Clinical Laboratories, Beijing Hospital, National Center of Gerontology, Beijing, P. R. China
Kun Zhong ; National Center for Clinical Laboratories, Beijing Hospital, National Center of Gerontology, Beijing, P. R. China
Shuai Yuan ; National Center for Clinical Laboratories, Beijing Hospital, National Center of Gerontology, Beijing, P. R. China
Falin He ; National Center for Clinical Laboratories, Beijing Hospital, National Center of Gerontology, Beijing, P. R. China
Yuxuan Du ; National Center for Clinical Laboratories, Beijing Hospital, National Center of Gerontology, Beijing, P. R. China
Zhehui Hu ; Party Committee Office, Beijing Hospital, National Center of Gerontology, Beijing, P.R. China
Zhiguo Wang ; National Center for Clinical Laboratories, Beijing Hospital, National Center of Gerontology, Beijing, P. R. China

Puni tekst: engleski, pdf (113 KB) str. 276-284 preuzimanja: 72* citiraj
APA 6th Edition
Wang, W., Zhong, K., Yuan, S., He, F., Du, Y., Hu, Z. i Wang, Z. (2018). National survey on internal quality control for tumour markers in clinical laboratories in China. Biochemia Medica, 28 (2), 276-284. https://doi.org/10.11613/BM.2018.020702
MLA 8th Edition
Wang, Wei, et al. "National survey on internal quality control for tumour markers in clinical laboratories in China." Biochemia Medica, vol. 28, br. 2, 2018, str. 276-284. https://doi.org/10.11613/BM.2018.020702. Citirano 26.01.2021.
Chicago 17th Edition
Wang, Wei, Kun Zhong, Shuai Yuan, Falin He, Yuxuan Du, Zhehui Hu i Zhiguo Wang. "National survey on internal quality control for tumour markers in clinical laboratories in China." Biochemia Medica 28, br. 2 (2018): 276-284. https://doi.org/10.11613/BM.2018.020702
Harvard
Wang, W., et al. (2018). 'National survey on internal quality control for tumour markers in clinical laboratories in China', Biochemia Medica, 28(2), str. 276-284. https://doi.org/10.11613/BM.2018.020702
Vancouver
Wang W, Zhong K, Yuan S, He F, Du Y, Hu Z i sur. National survey on internal quality control for tumour markers in clinical laboratories in China. Biochemia Medica [Internet]. 2018 [pristupljeno 26.01.2021.];28(2):276-284. https://doi.org/10.11613/BM.2018.020702
IEEE
W. Wang, et al., "National survey on internal quality control for tumour markers in clinical laboratories in China", Biochemia Medica, vol.28, br. 2, str. 276-284, 2018. [Online]. https://doi.org/10.11613/BM.2018.020702

Rad u XML formatu

Sažetak
Introduction: This survey was initiated to obtain knowledge on the current situation of internal quality control (IQC) practice for tumour markers (TMs) in China. Additionally, we tried to acquire the most appropriate quality specifications.
Materials and methods: This survey was a current status survey. The IQC information had been collected via online questionnaires. All of 1821 clinical laboratories which participated in the 2016 TMs external quality assessment (EQA) programme had been enrolled. The imprecision evaluation criteria were the minimal, desirable, and optimal allowable imprecisions based on biological variations, and 1/3 total allowable error (TEa) and 1/4 TEa.
Results: A total of 1628 laboratories answered the questionnaires (89%). The coefficients of variation (CVs) of the IQC of participant laboratories varied greatly from 1% (5th percentile) to 13% (95th percentile). More than 82% (82 - 91%) of participant laboratories two types of CVs met 1/3 TEa except for CA 19-9. The percentiles of current CVs were smaller than cumulative CVs. A number of 1240 laboratories (76%) reported their principles and systems used. The electrochemiluminescence was the most used principle (45%) and had the smallest CVs.
Conclusions: The performance of laboratories for TMs IQC has yet to be improved. On the basis of the obtained results, 1/3 TEa would be realistic and attainable quality specification for TMs IQC for clinical laboratories in China.

Ključne riječi
internal quality control; tumour marker; imprecision; biological variation

Hrčak ID: 198914

URI
https://hrcak.srce.hr/198914

▼ Article Information



Introduction

Although the diagnosis of cancer is mostly confirmed by biopsy which has been considered as “gold standard” for a long time, tumour markers (TMs) have an important role in staging and treatment of the cancer (1). Internal quality control (IQC) plays a significant role in the routine practice of clinical laboratories. The central role of IQC is to detect clinically important errors and evaluate repeatability in the analytical process. Only when the imprecisions of the measurement system in the laboratory are small enough, the staff might have the opportunity to get satisfactory and reliable results. Clinical laboratories evaluate the imprecisions of their own measurement systems by monitoring monthly (current) and long-time (cumulative) coefficients of variation (CVs) of IQC data, and the CVs are compared with different quality specifications (allowable imprecision criteria). The results of comparison could give the laboratories directions and suggestions to make their performances better. There are several standards which could be used to evaluate the CVs of IQC, such as the specifications based on biological variations including the minimal, desirable, and optimal allowable imprecisions, and 1/3 total allowable error (TEa) and 1/4 TEa. As the evaluation standards of the external quality assessment (EQA) in China were often set as TEa, the 1/3 TEa and 1/4 TEa could be calculated easily for each analyte whose TEa has been known before. Clinical laboratories in China have always used 1/3 TEa and 1/4 TEa to evaluate the imprecisions of their measurement systems (2). Although the 1/3 TEa and 1/4 TEa were convenient and easy to use, consideration of combining allowable imprecision specifications based on biological variations and different clinical requirements might be more suitable for all kinds of clinical laboratories regardless of size and conditions, which had gained a consensus recommendation among experts and clinical laboratories staff in recent years (3). From each TMs EQA program participating laboratory in China two types of CVs, the control rules, methods, instruments, reagents, calibrators and averages of 6 TMs (alpha-fetoprotein (AFP), carcinoembryonic antigen (CEA), total prostate specific antigen (PSA), cancer antigen 125 (CA125), cancer antigen 15-3 (CA15-3) and cancer antigen 19-9 (CA19-9)) IQC materials were collected. Then all the acquired CVs of IQC were analysed per 5 imprecision specifications (minimal, desirable, and optimal allowable imprecision based on biological variations, and 1/3 TEa and 1/4 TEa). After that we could get an overview of measurement imprecision for these 6 TMs in clinical laboratories in China. So far, IQC was one of the best ways to evaluate the imprecision of routine laboratory work in simple, convenient and effective way. There are some different measurement systems used to test TMs in China. We wanted to evaluate and compare their performances, and gain insight on which one is used the most and which one had the smallest imprecision.

Materials and methods

Materials

Clinical laboratories participating in the 2016 TMs EQA programme, organized by the National Center for Clinical Laboratories (NCCL) which had been the official EQA programs provider in China for more than 20 years, received survey questionnaires. A total of 1821 laboratories received the questionnaire and 1628 answered it (89%). The TMs included were: AFP, CEA, PSA, CA125, CA15-3 and CA19-9.

Methods

Our study was a current status survey. In June 2016, all the information was collected via a website developed by NCCL for conducting similar studies. The software (Clinet-EQA evaluation system) and website (http://www.clinet.com.cn/) were created by NCCL in 1998. In the beginning, they were used to collect and evaluate EQA program results. In 2016, all the participant laboratories which attended 2016 TMs EQA program were asked to return the investigation results online by the website including the following information: performing IQC or not, principle (the method for concentration determination of analyte), instrument, reagent (manufacturer and batch number), calibrator, number of IQC levels, average of each control (provided by laboratory staff), current CV (May 2016), and cumulative CV of results in-control (the results in-control meaning the results of IQC were in the acceptable ranges set by participant laboratories according to control rules). The CV was calculated and submitted by the participants. We collected two types of CVs: one was the CV of test results in-control for May 2016, the other one was cumulative CV of data in-control (the lot of IQC material unchanged). For the first one, laboratories needed to collect all the results of IQC in May 2016 which were in-control judged by their own control rules, which meant they must remove all the results out-of-control (the results out-of-control meaning the results of IQC were not in the acceptable ranges set by participant laboratories according to control rules) before calculation. For the second one, laboratories had to collect all the results in-control from the first to the last day until May 2016 with the lot of control unchanged. Then, the percentages of IQC CVs of the participants meeting the quality requirements for each TM were calculated per 5 imprecision criteria, which were the specifications based on biological variations including the minimal, desirable, and optimal allowable imprecision, 1/3 TEa and 1/4 TEa, respectively.

Imprecision criteria

Based on the performance evaluation requirements provided by Clinical Laboratory Improvement Amendment (CLIA’ 88), our institute set these criteria as the TEa for these 6 TMs. The 1/3 TEa and 1/4 TEa could be calculated and used to evaluate the imprecisions of the IQC of the participant laboratories in China. There were three imprecision levels which were calculated from biological variations and used to evaluate the performance of IQC, including: 1) minimum performance defined by CVA < 0.75C VI (CVA is analytical precision and CVI is the within-subject biological variation); 2) desirable performance defined by CVA < 0.50 CVI; 3) optimum performance defined by CVA < 0.25 CVI. The data we used referred to the biologic variation list provided by Ricos et al. (4).

Statistical analysis

Data were analysed using SPSS 13.0 (SPSS Inc, Chicago, IL, USA) and Clinet-EQA evaluation system V1.0 (Clinet Corp, Beijing, China), designed by NCCL and used in the national EQA program (see http://www.clinet.com.cn/shop/shop). The distributions of CVs of each analyte were tested by Kolmogorov-Smirnov test for normality. The related statistical parameters of CVs, including median, the 5th, 25th, 75th, and 95th percentile were calculated. The percentages of laboratories (total and divided into different subgroups by measurement systems) that met quality requirements of imprecision were calculated.

Results

The questionnaire was answered by 1628 laboratories (1628/1821, 89%). Laboratories which replied the survey submitted the related information and data for more than one TM. Table 1 shows the definitions of survey items. Table 2 shows the quality specifications of TMs based on CLIA’88 and biological variations, while Table 3 shows the numbers of participant laboratories, medians, other percentiles of two types of CVs, and the percentages of laboratories meeting quality requirements. Table 4 shows the principles and systems used for testing TMs; Table 5 and 6{ label needed for table-wrap[@id='t6'] } show the percentages of two types of CVs of different principles and systems meeting different imprecision criteria. These two types of CVs were shown abnormal distributions accessed by normality test.

Table 1 The content of the tumour marker IQC survey
ItemDefinition
Performing TMs IQC or not?If your laboratory have performed TMs IQC, choose yes otherwise choose no
PrincipleThe method of determination of concentration of analyte
InstrumentManufacturer and model
ReagentManufacturer and lot
CalibratorManufacturer and lot
Number of IQC controlsHow many levels
Average of each controlThe average in the TMs IQC chart
Current CVThe CV of all TMs IQC results in-control
Long-time (cumulative) CV of results in-controlThe CV of all TMs IQC results in-control from the first day to the last until May 2016 with the lot unchanged
TMs - tumour markers. IQC - internal quality control. CV - coefficient of variation.
Table 2 Quality specifications of tumour markers based on CLIA’88 and biological variation
Analyte1/3 TEa (%)1/4 Tea (%)Minimum performance (%)*Desirable performance (%)*Optimum performance (%)*
AFP86963
CEA861063
PSA861495
CA1258619126
CA15-386532
CA19-9861284
TMs - tumour markers. TEa - total allowable error. AFP - alpha-fetoprotein. CEA - carcinoembryonic antigen. PSA - total prostate specific antigen. CA125 - cancer antigen 125. CA15-3 - cancer antigen 15-3. CA19-9 – cancer antigen 19-9. *Performance according to biological variation.
Table 3 Survey results for the participating laboratories
Type of CVTMNCVs (%)Laboratories meeting allowable imprecision specifications based on CLIA’88 and biological variation (%)
Median5th25th75th95th1/3 TEa1/4 TEaMinimumDesirableOptimal
CurrentAFP13585237108869916724
CEA13675237108870927024
PSA11925137118769989146
CA125126341361091751009874
CA15-31199523711896945203
CA19-912476248127858957529
CumulativeAFP12435247118462885814
CEA12485247128261896214
PSA10986247128361978835
CA12511555247108865999764
CA15-31102624712845933102
CA19-911466249137350926920
CVs - coefficient of variations reported by participating laboratories. TM - tumour marker. TEa - total allowable error. N – number of participating laboratories. 5th, 25th, 75th, 95th – percentiles. AFP - alpha-fetoprotein. CEA - carcinoembryonic antigen. PSA - total prostate specific antigen. CA125 - cancer antigen 125. CA15-3 - cancer antigen 15-3. CA19-9 – cancer antigen 19-9.
Table 4 Principles and systems for tumour markers assays
GroupAssay principleSystem (manufacturer, city, country)Participating laboratories, N
AFPCEAPSACA125CA15-3CA19-9
1Acridine ester direct chemiluminescenceAbbott Architect i2000SR/i2000/i1000SR (Abbott,Chicago, USA)224223213203197183
Siemens Centaur /XP (Siemens, Berlin, Germany)12212573113106112
Siemens Centaur CP (Siemens, Berlin, Germany)222215181618
2Microparticle chemiluminescence - AMPPD labellingBeckman Access/Access 2 (Beckman, Brea, USA)272725262423
Beckman DXI 600, DXI 800 (Beckman, Brea, USA)139138117117114119
Shenzhen Mindray CL-2000i (Shenzhen, Guangdong, China)262624242223
3Luminol/Isoluminol chemiluminescenceDiaSorin S.p.A LIAISON (DiaSorin, Saluggia, Italia)171915151516
Maglumi 600/1000/1000plus/2000/2000plus/3000/4000 (Shenzhen, Guangdong, China)353632343335
4Flow fluorescence immunoassayLuminex100, 200 (Luminex, Austin, USA)303128312729
5ECLRoche Cobas e411 (Roche, Basel, Switzerland)848579848185
Roche Cobas e601/e602 (Roche, Basel, Switzerland)410415383404384406
Roche Modular E170/PP/P800 (Roche, Basel, Switzerland)606155585761
6Enzyme immuno-
chemiluminescence
AutoLumo A2000 (Zhengzhou, Henan, China)313225272626
TMs - tumour markers. ECL – electrochemiluminescence. AFP - alpha-fetoprotein. CEA - carcinoembryonic antigen. PSA - total prostate specific antigen. CA125 - cancer antigen 125. CA15-3 - cancer antigen 15-3. CA19-9 – cancer antigen 19-9. AMPPD - 3-(2’-spiroadamantane)-4-methoxy-4-(3”-phosphoryloxy)-phenyl-1,2-dioxetanes.
Table 5 Proportions of laboratories meeting different imprecision specifications with current coefficients of variation
TMPrinciple of assay (group)Allowable imprecision specifications based on CLIA’88 and biological variation (%)
1/3 TEa1/4 TEaMinimumDesirableOptimal
AFP18672708929
28664639015
37963628312
4772723873
59576739728
6523229656
CEA18467678914
28973749219
3734949825
4874242976
59579799737
65641417213
PSA18469869841
28773919850
37951899819
48650961004
59474979957
65632649212
CA125192839810082
289799810078
382599810059
474239410023
5967910010078
659377810037
CA15-31876914453
2896911373
375448276
47833070
5957629563
654238128
CA19-91653659919
28872859525
37143659627
4691762973
58874869945
62723277712
TM - tumour marker. Group 1 – acridine-ester direct chemiluminescence. Group 2 - microparticle chemiluminescence. Group 3 - luminol/isoluminol chemiluminescence. Group 4 - flow fluorescence immunoassay. Group 5 – electrochemiluminescence. Group 6 - enzyme immunochemical luminescence. TEa - total allowable error. AFP - alpha-fetoprotein. CEA - carcinoembryonic antigen. PSA - total prostate specific antigen. CA125 - cancer antigen 125. CA15-3 - cancer antigen 15-3. CA19-9 – cancer antigen 19-9.
{ label needed for table-wrap[@id='t6'] }
Table 6 Proportions of laboratories meeting different imprecision specifications with cumulative coefficients of variation
TMPrinciple of assay (group)Allowable imprecision specifications based on CLIA’88 and biological variation (%)
1/3 TEa1/4 TEaMinimumDesirableOptimal
AFP18264608519
2775749847
3724641769
4732017900
59169679516
6523030637
CEA1745455836
2846062888
35737376912
4842629943
59272739624
65630307811
PSA17957849727
28061859731
37249819830
4862993964
59168939746
65936649514
CA12518663979963
28567969963
373409810040
47416949716
594749910073
661357810035
CA15-3178565292
279525231
364369187
49615000
5916915442
65514999
CA19-91532648857
28354789415
36438578526
4761462933
58466829730
6322332779
TM - tumour marker. Group 1 – acridine-ester direct chemiluminescence. Group 2 - microparticle chemiluminescence. Group 3 - luminol/isoluminol chemiluminescence. Group 4 - flow fluorescence immunoassay. Group 5 – electrochemiluminescence. Group 6 - enzyme immunochemical luminescence. TEa - total allowable error. AFP - alpha-fetoprotein. CEA - carcinoembryonic antigen. PSA - total prostate specific antigen. CA125 - cancer antigen 125. CA15-3 - cancer antigen 15-3. CA19-9 – cancer antigen 19-9.

In Table 3 current CVs are listed and 5 out of 6 analytes (except CA19-9) showed relatively smaller CVs compared with CA19-9. The percentages of laboratories whose CVs were smaller than 1/3 TEa specification for these TMs were all above 87% (from 87% for PSA to 91% for CA125), while the percentages varied markedly (from 3% for CA15-3 to 74% for CA125) when the optimal allowable imprecision specification was used. Although current CVs of CA19-9 were larger than other TMs, the percentage of laboratories whose CVs were smaller than 1/3 TEa specification was close to 80% (974/1247). The percentages of laboratories whose CVs met imprecision criteria based on biological variations for CA15-3 were significantly smaller than other TMs. For the cumulative CVs, as the current ones, 5 TMs got relatively smaller CVs compared with CA19-9. The percentiles of current CVs of laboratories were lower than cumulative CVs.

A proportion of 76% laboratories (1240/1628) reported their principles and systems used. Table 4 shows the principles, systems, and numbers of laboratories of each system as well as the manufacturer’s information. We categorized the principles of assay into 6 groups including: 1) acridine ester direct chemiluminescence; 2) microparticle chemiluminescence-3-(2’-spiroadamantane)-4-methoxy-4-(3”-phosphoryloxy)-phenyl-1,2-dioxetanes (AMPPD) labelling; 3) luminol/isoluminol chemiluminescence; 4) flow fluorescence immunoassay; 5) electrochemiluminescence (ECL); 6) enzyme immunochemical luminescence. The ECL was the most used of all the 6 principles. About 45% of laboratories used ECL principle (Group 5) to test TMs. The principles used fewest were flow fluorescence immunoassay (Group 4) and enzyme immunochemical luminescence (Group 6), the percentages were all about 3%. Coincidentally, the percentages of group 5 meeting the specifications were the highest while group 4 and 6 were the lowest.

Table 5 and table 6 show the information about the percentages of current CVs and cumulative CVs meeting different imprecision criteria for all groups. The results of group 5 were better compared to others. Almost all the assay principles could archieve more than 80% of laboratories meeting the minimum imprecision criterion based on biological variation except CA15-3. However, judging by the strictest specification based on biological variations (i.e. the optimal), almost all the percentages were lower than 50%. The results of group 6 were not so encouraging for almost all the imprecision criteria.

Discussion

The results of our survey suggest that there were remarkable variations for the TMs IQC in China, including manufacturer, principle and imprecision. Harmonized control rules with defined ranges of imprecisions were not defined in China. Some studies only kept their focus on the performances of different test systems (5). Compared with Bertsch et al. the range of CVs for CA19-9 IQC was much wider in our study. The performances should be improved later (5). Consequently, the lack of standards might lead to many problems in daily monitoring of imprecision. The wide ranges of current and cumulative CVs of TM IQC materials reported by the participant laboratories, which varied dramatically (from less than 1% to more than 50%) also shocked us.

Cancer antigen 19-9 had the largest CVs of all TMs, which presented that Chinese laboratories should pay more attention to this analyte. The cumulative CVs were slightly larger than current CVs, which might reveal that the long-time repeatability was not as good as short-term one. We might provide some suggestions such as: 1) about 80% Chinese clinical laboratories with better medical resource could meet the 1/3 TEa criteria which could be considered as evaluation standard for IQC program; 2) the cumulative CVs were larger than current CVs, which means that more attention should be paid to long-time repeatability. The ideal situation should be, the longer a lot of IQC material tested, the smaller CVs should be. That was because with the increasing of test times, the results and variation should be more and more stable, if the test system had been stable all the time. The long-time stability of measurement system should be improved in China.

Cancer antigen 15-3 had the strictest specification based on biological variation, which made the percentages of laboratories meeting criteria much lower than other TMs. So we should know that 1/3 TEa should be used carefully because it was much bigger than the specifications based on biological variation. We might pay more effort on finding a better and more reasonable IQC evaluation criterion which could better match the performance of test system and biological variations in the future.

The ECL method had the highest CVs of TMs IQC meeting the evaluation specifications, which might be one of the reasons why most laboratories chose ECL method. A study also verified that the ECL method and Roche test system could achieve a good performance in TMs measurement (6). Compared with other analytes in Chinese Proficiency testing (PT) panel, creating national evaluation specifications for imprecision of TMs was needed to improve the quality of measurement (7, 8).

Clinical laboratories in this study were located in different areas of China and could be considered as representatives of Chinese clinical laboratories with better medical resources and more concern on their performance than those who did not participate to TMs EQA program or return the questionnaires. Most of the clinical laboratories participating in these kinds of surveys were mostly first-class hospitals in China (9, 10).

There were still some limitations in our study. Human epidermal growth factor receptor 2 (HER2) was a TM which was newer than these 6 TMs and it had been in focus in recent years. There is another way to perform IQC for HER2 and we should keep up with the time (11). Another study reported that lyophilized QC materials for TMs were insufficiently stable for use in quality control among clinical laboratories (12). This might result in cumulative CVs bigger than current ones, which might be studied in the further studies. In Lent et al. study, they made a conclusion that treatment errors in association with PSA determinations could therefore be uniformly and plausibly assessed using objective criteria and could thus be avoided (13). IQC was an effective way to decrease errors occurrence. We might combine IQC to evaluate treatment errors occurrence rate to study the relationship between them.

In conclusion, the performance of laboratories for TMs IQC has yet to be improved. On the basis of the obtained results, 1/3 TEa would be realistic and attainable quality specification for TMs IQC for clinical laboratories in China.

Acknowledgments

We thank all laboratories and institutions that participated in the TMs EQA programme organized by NCCL. We also appreciate Clinet website (www.clinet.com.cn) that provided computer technology support to establish the website for similar studies and relevant services.

Notes

[1] Conflicts of interest None declared.

References

1 

Koepke JA. Molecular marker test standardization. Cancer. 1992;69:1578–81. [Error! Hyperlink reference not valid.] DOI: http://dx.doi.org/10.1002/1097-0142(19920315)69:6+<1578::AID-CNCR2820691312>3.0.CO;2-K PubMed: http://www.ncbi.nlm.nih.gov/pubmed/1540898

2 

Zeng R, Wang W, Zhao HJ, Fei Y, Wang ZG. National Survey on Internal Quality Control for HbA1c Analytical Instruments in 331 Hospital Laboratories of China. Clin Lab. 2015;61:453–60. DOI: http://dx.doi.org/10.7754/Clin.Lab.2014.141123 PubMed: http://www.ncbi.nlm.nih.gov/pubmed/26118175

3 

Skitek M. Acceptability limits based on biology goals in haematology EQAS. Accredit Qual Assur. 2005;10:112–5. DOI: http://dx.doi.org/10.1007/s00769-004-0889-8

4 

Ricos C, Alvarez V, Cavas F, Garcia-Lario JV, Hernandez A, Jimenez CV, et al. Desirable specifications for total error, imprecision, and bias, derived from intra- and inter-individual biologic variation. Available at: http://www.westgard.com/biodatabase1.htm. Accessed January 5th 2018.

5 

Bertsch T, Aschenneller C, Bewarder N, Beyrau R, Herrmann BL, Jansen E, et al. European proficiency study with control serum for the tumor marker CA 19-9 measured on different test systems. Clin Lab. 2013;59:185–92. DOI: http://dx.doi.org/10.7754/Clin.Lab.2012.111112 PubMed: http://www.ncbi.nlm.nih.gov/pubmed/23505925

6 

Dolci A, Scapellato L, Mozzi R, Panteghini M. Imprecision of tumour biomarker measurements on Roche Modular E170 platform fulfills desirable goals derived from biological variation. Ann Clin Biochem. 2010;47:171–3. DOI: http://dx.doi.org/10.1258/acb.2009.009228 PubMed: http://www.ncbi.nlm.nih.gov/pubmed/20144978

7 

Zhong K, Zhao Y, Xiao YL, Wang W, He FL, Wang ZG. 8-year review of laboratory performance on blood lead level external quality assessment surveys 2006–2013 in China: continual improvement. Accredit Qual Assur. 2015;20:25–8. DOI: http://dx.doi.org/10.1007/s00769-014-1097-9

8 

Zhong K, Wang W, He FL, Wang ZG. Neonatal screening external quality assessment in China, 2014. J Med Screen. 2015;22:175–81. DOI: http://dx.doi.org/10.1177/0969141315592924 PubMed: http://www.ncbi.nlm.nih.gov/pubmed/26092840

9 

Zeng R, Wang W, Wang ZG. National survey on critical values notification of 599 institutions in China. Clin Chem Lab Med. 2013;51:2099–107. DOI: http://dx.doi.org/10.1515/cclm-2013-0183 PubMed: http://www.ncbi.nlm.nih.gov/pubmed/23839815

10 

Zhong K, Wang W, He FL, Wang ZG. The status of neonatal screening in China, 2013. J Med Screen. 2016;23:59–61. DOI: http://dx.doi.org/10.1177/0969141315597715 PubMed: http://www.ncbi.nlm.nih.gov/pubmed/26238341

11 

Ngo C, Laé M, Ratour J, Hamel F, Taris C, Caly M, et al. Internal quality control on HER2 status determination in breast cancers: Experience of a cancer center. Bull Cancer. 2017;104:608–17. DOI: http://dx.doi.org/10.1016/j.bulcan.2017.05.002 PubMed: http://www.ncbi.nlm.nih.gov/pubmed/28595742

12 

Ahn S, Park J, Kim YR, Kim JH, Kim HS. Stability of lyophilized pooled sera as quality control materials for tumor marker assays in external quality assessment. Clin Chim Acta. 2017;471:233–42. DOI: http://dx.doi.org/10.1016/j.cca.2017.05.035 PubMed: http://www.ncbi.nlm.nih.gov/pubmed/28579142

13 

Lent V, Baumbusch F, Weber B. Criteria for errors in prostate-specific antigen diagnostics. Urologe A. 2012;51:1558–61. DOI: http://dx.doi.org/10.1007/s00120-012-2968-5 PubMed: http://www.ncbi.nlm.nih.gov/pubmed/22801817


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