External quality control assessment in PCR diagnostics of dengue virus infections

BACKGROUND: Increased travelling to countries endemic for dengue fever (DF) demands efficient laboratory diagnostics. Nucleic acid amplification techniques (NAT) are now frequently used for rapid diagnosis of imported viral diseases. Different PCR systems are available. OBJECTIVES: In order to assess the quality of molecular diagnostics of dengue virus infections, an external quality assurance (EQA) in PCR diagnostics was conducted. Study design: A panel of 10 human plasma samples was prepared and spiked with dengue virus types DEN-1 to DEN-4. In addition, a 10-fold dilution series (1:10-1:10(4) ) of DEN-3 virus was included. The panel was pre-tested by nested RT-PCR, in-house real-time PCR, and a commercial real-time PCR kit. The samples were inactivated by gamma irradiation and shipped in freeze dried state. Thirteen laboratories, within the European network for the diagnostics of imported viral diseases (ENIVD) took part using either single-round, nested, or real-time RT-PCR methods. Two laboratories used two methods in parallel, summarising up to 15 comparable results. RESULTS: 33-100% correct results were achieved. All laboratories detected DEN-2 correctly, followed by DEN-1 (14 positive results of 15), DEN-3 (12/15) and DEN-4 (11/15). Testing of the serial dilution revealed low sensitivity in many labs, with results ranging from 33 to 80% of correctly tested samples. CONCLUSION: The EQA gives a feedback of the quality of the RT-PCR system used by each respective laboratory. The different test systems and amplification conditions demonstrate the importance of external quality control measures.     

湖南省2005年病毒血清学检验室间质量评价分析

目的通过分析病毒血清学室间质量评价工作，探讨影响各参评实验室成绩的相关因素，提高检验人员的质控意识，提高临床免疫学实验室的水平和质量。方法全年组织室间质评两次，每次发放5个批次的标本，要求各参评实验室按规定的时间检测并回报结果，结果评价采用我国临床免疫学定性项目PT评价方案。结果医疗机构实验室的PT平均分92％，采供血机构实验室PT平均分93％。结论全省的室问质评成绩有一定的可比性，为全省临床实验室提供了技术和信息平台，对于提高实验室检测水平有一定帮助。但在室内质量控制方面有待加强。     

Towards improved diagnosis of von Willebrand disease: Comparative evaluations of several automated von Willebrand factor antigen and activity assays

Introduction

von Willebrand disease (VWD) is reportedly the most common bleeding disorder and arises from deficiency and/or defects of von Willebrand factor (VWF). Laboratory diagnosis and typing has important management implications and requires a wide range of tests, including VWF activity and antigen, and involves differential identification of qualitative vs quantitative defects.

Methods

We have assessed several VWF antigen and activity assays (collagen binding [VWF:CB], ristocetin cofactor [VWF:RCo] and the new Siemens INNOVANCE assay [VWF:Ac], employing latex particles and gain of function recombinant glycoprotein Ib to facilitate VWF binding and agglutination without need for ristocetin) using different instrumentation, including the new Sysmex CS-5100, with a large sample test set (n = 600). We included retrospective plus prospective study designs, and also evaluated desmopressin responsiveness plus differential sensitivity to high molecular weight VWF.

Results

VWF:Ag and VWF:RCo results from different methods were respectively largely comparable, although some notable differences were evident, including one high false normal VWF:Ag value (105 U/dL) on a type 3 VWD sample, possibly due to heterophile antibody interference in the latex-based CS-5100 methodology. VWF:Ac was largely comparable to VWF:RCo, but VWF:CB showed discrepant findings to both VWF:RCo and VWF:Ac with some patients, most notably patients with type 2M VWD.

Conclusions

(a) VWF:Ag on different platforms are largely interchangeable, as are VWF:RCo on different platforms, except for occasional (some potentially important) differences, and manufacturer recommended methods may otherwise require some assay optimization; (b) VWF:RCo and VWF:Ac are largely interchangeable, except for occasional differences that may also relate to assay design (differing optimizations); (c) VWF:CB provides an additional activity to supplement VWF:RCo or VWF:Ac activity assays, and is not interchangeable with either.     

串联质谱检测氨基酸和酰基肉碱的室间质量评价

目的调查我国部分新生儿筛查实验室串联质谱检测氨基酸和酰基肉碱的水平和现状。方法向19家新生儿筛查实验室发放5个批号（201211、201212、201213、201214、201215）的血斑质控品,收集实验室回报的氨基酸和酰基肉碱检测值,对回报的结果按照方法分组进行统计分析,并评价其检测水平。结果 18家实验室回报了检测结果,回报率为94.7%。回报结果的18家实验室中有14家实验室采用衍生非配套的试剂检测氨基酸和酰基肉碱,有3家实验室采用衍生配套的试剂检测氨基酸和酰基肉碱,有1家实验室采用非衍生的方法检测氨基酸和酰基肉碱。按照方法学分组同时考虑是否使用配套试剂计算各组及格率,其中,瓜氨酸项目及格率为71.4%～100.0%,亮氨酸项目的及格率为71.4%～100.0%,甲硫氨酸项目的及格率为42.5%～100.0%,苯丙氨酸项目及格率为71.4%～100.0%,酪氨酸项目及格率为71.4%～100.0%,缬氨酸项目的及格率为66.7%～100.0%,游离肉碱项目的及格率为42.9%～100.0%,丙酰肉碱项目的及格率为28.6%～100.0%,异戊酰肉碱项目的及格率为33.3%～92.9%,辛酰肉碱项目的及格率为28.6%～100.0%,月桂酰肉碱项目的及格率为46.2%～100.0%,棕榈酰肉碱项目的及格率为64.3%～100.0%,十八碳酰肉碱项目的及格率为71.4%～100.0%。结论目前串联质谱检测氨基酸和酰基肉碱的质量水平差异较大,开展室间质评项目计划有利于提高我国遗传代谢病的检测领域整体水平。     

Quality specifications in EQA schemes: from theory to practice

BACKGROUND: External quality assessment (EQA) is a tool for quality management in clinical laboratories and its main objectives are assessment of participants and methods performance, training and advice. This paper describes the quality specifications used in EQA schemes of the Centre of Biomedical Research (CRB), in order to design schemes that can assess laboratory reliability performances, meet the changing needs and quality recommendations. METHODS: Quality specifications for control materials, statistical procedures and goals to assess laboratory performance have been applied and introduced in EQA schemes managed by CRB. RESULTS: The application of well-defined quality specifications has demonstrated effective. In particular, we report results on alkaline phosphatase and cholesterol obtained using commercial control materials and human serum controls, in two different EQA surveys; the inter-laboratory variability (CVinter%) for troponin I analysed with a diagnostic system and assigned values of CK-MB mass obtained using four different diagnostic systems; the percentage of acceptable performances obtained by means of the application of goals based on clinical criteria, biological variation, state-of-the-art and used for EQA schemes, and referring to some analytes with significant clinical values such as cholesterol, glucose, glycated hemoglobin and sodium. CONCLUSIONS: The design of reliable EQA schemes based on evidence-based quality specifications is a pre-requisite for supporting the quality improvement of clinical laboratories.     

Sysmex XT-2000i血液细胞分析仪在临床检验的应用

目的建立并探讨全血细胞分析质量控制的工作程序。方法总结2011年所有与全血细胞分析质量控制有关的数据和材料,包括每天的室内质量控制数据、卫生部临检中心室间质量评价结果、室内质量控制失控记录、不符合要求标本的记录和显微镜复检病例的登记。结果全年室内质量控制共有6次失控,查明原因后及时进行了纠正,卫生部临检中心室间质量评价全年满分通过,平均偏倚大大低于部中心的允许范围。不符合要求的标本共575份,全年共进行了1 403例显微镜复检,复检率3.9%。结论全血细胞分析的质量控制除强调检验中血细胞分析仪计数的质量控制外,还应重视检验前的标本控制和检验后的结果分析,以及血涂片的人工复检。另外,定期回顾分析室内室间质量控制数据和各种记录,有助于今后进一步提高全血细胞分析的质量控制工作。     

贵州省县级结核病实验室盲法复检效果分析

目的探讨盲法复检在贵州省县级结核病实验室痰检工作中的应用。方法分析贵州省2005—2011年县级结核病实验室盲法复检资料。结果2005—2008年合计痰细胞,大小,厚薄,染色,脱落符合率分别为84．55％、84．22％、83．04％、88．18％和89．88％,2005—2011年阳性,阴性和总符合率分别为96．64％、99．07％和98．72％,各符合率均呈年度上升趋势,年度间差异有统计学意义。结论盲法复检能反应实验室痰检质量的真实水平,定期分析盲法复检数据是提高痰检质量的重要保证。     

Harmonization and external quality assessment of antithrombin activity assays

In the framework of a Dutch project named “Calibration 2000” harmonization of antithrombin activity assays was studied. The commutability of potential calibrators for antithrombin was assessed by means of a twin-study design, which is a multicentre, split-patient sample, between-field-methods protocol. The twin-study consisted of simultaneous analysis of fresh-frozen patient plasmas and three potential calibrators for antithrombin by 30 Dutch laboratories forming 15 couples. The state-of-the-art intralaboratory standard deviation (SD_SA) was used to assess the commutability of the potential calibrators. The regression line residuals for the potential calibrators were normalized by expressing them as multiples of SD_SA. All residuals of the potential calibrators were within the 3 × SD_SA limit. One potential calibrator was used in an attempt to harmonize antithrombin assay results in a Dutch field study. The interlaboratory coefficient of variation (CV) of the antithrombin results for three test samples could be reduced from 6.9 - 13.2% (before harmonization) to 5.6 - 9.8% using the common calibrator.

Conclusion

The potential calibrators were commutable. Limited harmonization was achieved by using a common calibrator for all participants.     

利用实验室质控数据评定血常规项目测量不确定度研究

目的：探讨利用室内质量控制（internal quality control,IQC）和室间质量评价（external quality assessment,EQA）数据评定血常规项目测量不确定度。方法：收集南通大学附属医院检验科2014年～2016年累积30个月白细胞计数（WBC）、红细胞计数（RBC）、血红蛋白浓度（HGB）和血小板计数（PLT）等4个项目IQC在控数据以及2015年卫生部（和江苏省）临检中心EQA回报结果,采用自上而下方法评定4个血常规项目的测量不确定度。结果：利用IQC数据结合国家EQA数据评定的相对合成标准不确定度（% uc）分别为2.62、2.34、1.96和4.59;利用IQC数据结合江苏省EQA数据评定的% uc分别为2.59、1.40、1.58和3.97,均小于按中华人民共和国卫生行业标准WS/T 406-2012《临床血液学检验常规项目分析质量要求》设置的目标不确定度。结论：采用实验室的质控数据可较方便地反映XE-2100五分类全自动血细胞分析仪WBC、RBC、HGB和PLT等4个项目测量不确定度,具有一定临床应用价值。     

First international external quality assessment of molecular diagnostics for Mers-CoV

BackgroundSince the discovery of Middle East respiratory syndrome coronavirus (MERS-CoV) in 2012, diagnostic protocols were quickly published and deployed globally.ObjectivesWe set out to assess the quality of MERS-CoV molecular diagnostics worldwide.Study designBoth sensitivity and specificity were assessed using 12 samples containing different viral loads of MERS-CoV or common coronaviruses (OC43, 229E, NL63, HKU1).ResultsThe panel was sent to more than 106 participants, of which 99 laboratories from 6 continents returned 189 panel results.Scores ranged from 100% (84 laboratories) to 33% (1 laboratory). 15% of respondents reported quantitative results, 61% semi-quantitative (Ct-values or time to positivity) and 24% reported qualitative results. The major specific technique used was real-time RT-PCR using the WHO recommended targets upE, ORF1a and ORF1b. The evaluation confirmed that RT-PCRs targeting the ORF1b are less sensitive, and therefore not advised for primary diagnostics.ConclusionsThe first external quality assessment MERS-CoV panel gives a good insight in molecular diagnostic techniques and their performances for sensitive and specific detection of MERS-CoV RNA globally. Overall, all laboratories were capable of detecting MERS-CoV with some differences in sensitivity. The observation that 8% of laboratories reported false MERS-CoV positive single assay results shows room for improvement, and the importance of using confirmatory targets.