Point-of care testing and EQA: a look in the current literature

Internal quality control and external quality assessment on POCT
Kuwa K. Rinsho Byori 2015; 63 (2): 224–31 (in Japanese).
 
The quality management (QM) of POCT summarises its internal quality control (IQC) and external quality assessment (EQA). For QM requirements in POCT, ISO 22870 (Point-of-care testing [POCT] –Requirements for quality and competence) and ISO 15189 (Medical laboratories – Requirements for quality and competence) apply and are performed under the guidance of the QM committee. The role of the POC coordinator and/or medical technologist in the clinical laboratory is important. Regarding POCT devices, it is necessary to confirm data on measurement performance from the manufacturer and not rely on information provided in the associated insert document. In the IQC programme, the checking and control of measurement performance are the targets. On measurements of QC samples by the manufacturer, it is essential to check the function of devices. In addition, regarding the EQA programme, in two neighbouring facilities there was a move to confirm the current status of measurement and commutability assessment in these laboratories using whole blood, along with residual blood samples from daily examinations in the clinical laboratory.
 
Establishing an external quality assessment scheme for point-of-care international normalized ratio in Thailand
Tientadakul P, Chuntarut A. Int J Lab Hematol 2015; 37 (4): 509–14.
 
Effective warfarin therapy management has gained national interest, resulting in the increased use of point-of-care testing (POCT) for international normalised ratio (INR). External quality assessment (EQA) is recommended to ensure quality of the testing. CoaguChek XS and CoaguChek XS Plus are the only commonly available POCT INR monitors in Thailand. Therefore, Thailand NEQAS for Blood Coagulation initiated the scheme for POCT INR in 2013, including only hospitals using these devices. Questionnaires were sent to the hospitals, enquiring about their interest in EQA participation. Two surveys were distributed; each included five certified European Concerted Action on Anticoagulation (ECAA) INR plasma sets. Unsatisfactory performance was indicated by a 15% deviation from the certified mean INR value. There were 156 hospitals using the devices. Thirty-five responded to the questionnaire. Medical personnel undertaking POCT INR were limited to laboratory staff in 29 (83%) of these centres, and 31 hospitals actually participated. The median of results from participants was the same or nearly the same as the certified mean INRs. External quality assessment for POCT INR in Thailand is feasible using the ECAA plasmas as control materials. The results therefore appear encouraging to other developing countries to establish their own EQA schemes.
 
 
Preparation of control blood for external quality assessment of point-of-care international normalized ratio testing in the Netherlands
van den Besselaar AM, Abdoel CF, Ardanary D, van de Kamp G, Versluijs FA.
Am J Clin Pathol 2014; 141 (6): 878–83.
 
The aim of this study was to prepare control blood for an external quality assessment (EQA) scheme for international normalised ratio (INR) point-of-care testing (POCT) in The Netherlands, and to assess the performance of the participants. Control blood was prepared from dialysed, pooled patient plasma and washed human erythrocytes. Samples of control blood were mailed to participants of The Netherlands EQA scheme from October 2006 through to December 2012.
Most participants used CoaguChek XS (Roche Diagnostics, Mannheim, Germany) devices for POCT. The median between-centre coefficient of variation (CV) of the reported INR decreased from 4.5% in 2006 to 2.6% in 2012. A few participants used the ProTime Microcoagulation System (ITC, Edison, NJ) for POCT. The decrease in median CV (per year) of the INR with this system was 7.0% to 10.6%. The control blood samples were useful for EQA in The Netherlands. The participants' performance with the CoaguChek XS system improved with time, demonstrating the value of external quality assessment.
 
 
External quality assessment of point-of-care international normalized ratio (INR) testing in Europe
Stavelin A, Meijer P, Kitchen D, Sandberg S. Clin Chem Lab Med 2011; 50 (1): 81–8.
 
Point-of-care testing (POCT) of prothrombin time, expressed as international normalised ratio (INR), is widely used to monitor patients on oral anticoagulation treatment. Guidelines recommend that POCT users should participate in an external quality assessment (EQA) scheme whenever available. The aim of this study was to investigate which European countries provide EQA for POCT INR and to compare how these schemes are organised. Thirty European countries were invited to participate in this study. Those which reported that they provide EQA for POCT INR filled in a questionnaire dealing with different aspects of their schemes. Nineteen countries reported that they do not provide EQA for POCT INR, while 12 organisations from nine countries reported that they provide this service. Most of these countries circulate lyophilised samples of unknown target value to participants. Samples with certified INR values and procedures using split samples with fresh patient samples are also used. The acceptability limits vary from 15% to 30%, and the total number of samples circulated per year varies from one to 12. Most of the countries organise educational activities together with their schemes. This study demonstrated that there is wide variation in the way EQA for POCT INR is performed in Europe, and that there are many European countries that do not provide this service. Even though these findings indicate that EQA for POCT INR draws some challenges, especially in providing suitable control materials, participation in such schemes is considered useful.
 
 
 
Use of quality indicators to compare point-of-care testing errors in a neonatal unit and errors in a STAT central laboratory
Cantero M, Redondo M, Martín E, Callejón G, Hortas ML. Clin Chem Lab Med 2015; 53 (2): 239–47.
 
Point-of-care testing (POCT), like other laboratory tests, can be affected by errors throughout the total testing process. To evaluate quality error rates, the use of quality indicators (QIs) is recommended; however, little information is available on the quality error rate associated with POCT. The objective of this study was to investigate quality error rates related to POCT and compare them with central laboratory (CL) testing. The authors studied standardised QIs for POCT in comparison to CL testing, and compared error rates related to requests, collection, and handling of samples and results from an external quality assessment EQA programme and internal quality control (IQC). The highest difference between POCT and CL testing was observed for QI related to patient identification (45.3% vs. 0.02%; P<0.001). Regarding specimen collection and handling, the QI related to samples without results was also higher in POCT than in CL testing (15.8% vs. 3.3%; P<0.001). For the QI related to insufficient sample volume, the authors obtained 2.9% vs. 0.9% (P=0.27). Unlike QIs for the pre-analytical phase, QIs for the analytical phase had better results in POCT than CL testing. Results showed 8.3% vs. 16.6% (P=0.13) for QI related to unacceptable results in EQA, and 0.8% vs. 22.5% (P<0.001) for QI related to unacceptable results in IQC. These results show that the pre-analytical phase remains the main problem in POCT and that monitoring of quality indicators is a very valuable tool in reducing errors in POCT.
 
 
Retrospective analysis of 55,769 HbA1c EQA results obtained from professional laboratories and medical offices participating in surveys organized by two European EQA centers over a nine-year period
Morandi PA, Deom A, Kesseler D, Cohen R. J Clin Lab Anal 2011; 25 (5): 337–43.
 
External quality assessment (EQA) is an essential tool for laboratories to monitor the performances of their analyses. It also allows a comparison of methods and types of laboratories (professional laboratories vs. medical offices). Therefore, this study compared 55,769 HbA1c EQA results obtained between 1999 and 2008 by laboratories participating in EQA schemes organised by two European centres (Switzerland [Centre 1] and France [Centre 2]). Simple, non-parametrical statistics suited to EQA results were used to calculate the yearly and global precision performances. All the results, including the outliers, were included in the calculations. The best global precision performances were obtained by professional laboratories and medical offices using DCA POCT devices, followed by professional laboratories with the Integra, Hitachi, cobas Mira, and HPLC groups of devices, and finally by both types of laboratories with the NycoCard POCT devices. When considering yearly precision performances, an overall improvement over time was observed for almost all diagnostic devices in Centre 1, whereas the trend was less clear for Centre 2. The HbA1c EQA results collected and analysed over a nine-year period showed that the DCA POCT devices used either by professional laboratories or medical offices had better reproducibility than laboratory devices (other than POCT), and that a general improvement of yearly precision performances was observed, especially when frequent EQA schemes were organised.
 
 
Point-of-care testing in haemostasis
Perry DJ, Fitzmaurice DA, Kitchen S, Mackie IJ, Mallett S. Br J Haematol 2010; 150 (5): 501–14.
 
Point-of-care testing (POCT) in haematology has seen a significant increase in both the spectrum of tests available and the number of tests performed annually. POCT is frequently undertaken with the belief that this will reduce the turnaround time for results and so improve patient care.
The most obvious example of POCT in haemostasis is the out-of-hospital monitoring of the international normalised ratio (INR) in patients receiving a vitamin K antagonist, such as warfarin. Other areas include the use of the activated clotting time to monitor anticoagulation for patients on cardiopulmonary bypass, platelet function testing to identify patients with apparent aspirin or clopidogrel resistance, and thrombelastography to guide blood product replacement during cardiac and hepatic surgery. In contrast to laboratory testing, POCT is frequently undertaken by untrained or semi-trained individuals, and in many cases is not subject to the same strict quality control programmes that exist in the central laboratory. Although external quality assessment programmes do exist for some POCT assays these are still relatively few. The use of POCT in haematology, particularly in the field of haemostasis, is likely to expand and it is important that systems are in place to ensure that the generated results are accurate and precise.
 
 
Problems and practical solutions in the external quality control of point of care devices with respect to the measurement of blood glucose
Wood WG. J Diabetes Sci Technol 2007; 1 (2): 158–63.
 
Point of care testing (POCT) is evolving at an ever- increasing rate. This article deals mainly with the aspect of POCT for blood glucose and the problems of external quality assessment (EQA) of point-of-care testing (POCT) devices. At the present time it is only possible to control precision with EQA, independent of the matrix of the test materials (synthetic polymer-base, plasma/serum, or processed whole blood). The German Federal Medical Council guidelines for laboratory performance allow an interlaboratory imprecision of ±16%. The majority of POCT devices fulfil these requirements. The long-term stability of results – tested by repeated distribution of the same materials over a 12-month period – is excellent, and the performance of POCT devices under routine conditions is usually excellent in terms of results comparability. However, the problems of accuracy in terms of control materials have still to be mastered.
 
 
Experience with an external quality assessment programme for point-of-care-testing (POCT) devices for the determination of blood glucose
Wood WG, Hanke R, Meissner D, Reinauer H. Clin Lab 2003; 49 (3–4): 151–9.
 
This article describes the preparation and internal and external evaluation of materials, critical issues in the external quality assessment (EQA) of point-of-care testing (POCT) devices for measuring blood glucose. A comparison was made between different materials, both of natural and synthetic origin, and with and without stabilisers. The aims were to produce a material which was compatible with as many POCT devices as possible and so reduce the number of materials sent out in each campaign, as well as to optimise the precision and comparability of results between methods and devices. Although the use of near-natural material – sterile-filtered plasma spiked with glucose –survived internal testing, this material proved to be unsuitable for EQA surveys. The study resulted in the reduction of materials for each survey to stabilised whole blood for one device, stabilised plasma for two devices, and a synthetic material based on a polyethylene glycol matrix for all other devices. Samples were sent as pairs six times annually. The POCT devices tested measured precisely but inaccurately in the synthetic material, when compared with the reference method (gas chromatography coupled with isotope-dilution mass-spectrometry [GC-IDMS]), so that the devices could only be evaluated for precision. The construction of ratios between the concentrations measured on the two samples distributed allowed an indirect assessment of accuracy. The need for surveillance of POCT devices is stressed in this publication, which combines theory and practice in setting up and running an EQA programme for blood glucose.
 
 
Point-of-care (POCT) prothrombin time monitors: is a periodical control of their performance useful?
Barcellona D, Fenu L, Cornacchini S, Marongiu F. Thromb Res 2009; 123 (5): 775–9.
 
Point-of-care testing (POCT) prothrombin time (PT) monitors are now used widely to monitor oral anticoagulant treatment. Although portable coagulometers are extremely easy to use, checking the quality of their performance presents some difficulties. The aims of this study were to investigate on a quarterly basis the performance of 95 Coagucheck S assigned to 99 anticoagulated patients at home. This was done by checking the monitors versus a reference coagulometer in the laboratory at the authors’ thrombosis centre (TC). The other aims were to carry out an external quality assessment employing different sets of INR-certified plasmas with five different ranges of anticoagulation, and to assess the performance of the different lots of strips employed by the patients during the study. No difference between the PT INR obtained with both systems at the first quarterly check was noted, but a significant difference was found when the two systems were compared at the second and third quarterly checks. The Bland-Altman test showed increased disagreement between the first and the third controls. The percentage of INR values that showed a difference of ±0.5 INR units in the PT values performed with both systems was: 1.0% (first control), 7.5% (second control) and 11.5% (third control) (χ2 8.315, P=0.0156).
Lots with differences higher than 10% in terms of ±0.5 INR Units at the first, second and third controls were 16%, 20.8% and 61%, respectively. Seven monitors (7.3%) failed to test one or two of the INR-certified plasmas of one set but performed well using a second set of plasmas. Three monitors (3.1%) failed to test two sets of plasmas but performed well using a different lot of strips (from 279A to 483A). One monitor (1%) gave unsatisfactory results with different sets of plasmas and strips. All the other PT INR obtained with the monitors fell well within the different ranges of the INR-certified plasmas. Anticoagulated patients using self-testing or self-management should periodically bring their portable coagulometer to a reference TC, especially when strip ‘lot’ has to be changed, and therefore the role of the TC appears crucial in this regard.