DÄ internationalArchive33/2010Point-of-Care Testing in Hospitals and Primary Care

Review article

Point-of-Care Testing in Hospitals and Primary Care

Dtsch Arztebl Int 2010; 107(33): 561-7. DOI: 10.3238/arztebl.2010.0561

Junker, R; Schlebusch, H; Luppa, P B

Background: Many medical laboratory tests can now be done near the patient (point-of-care testing, POCT), ranging from basic blood glucose measurement to complex coagulation testing. Switching from conventional laboratory testing to POCT shortens the time to decision-making about further testing or treatment, as delays are no longer caused by specimen transport and preparation, and the test results are rapidly available at the point of care. Better medical outcomes and lower costs may ensue.

Method: Selective literature review.

Results: The available methods and equipment enable persons not specially trained in laboratory medicine to perform high-quality laboratory testing at the point of care, under certain conditions. Before POCT is introduced in a hospital or outpatient practice, a cost-benefit analysis should be performed, because the introduction is costly and requires a certain amount of organizational work especially for quality management. The potential medical and economic benefits should be assessed individually in each case.

Conclusion: POCT for certain applications is a useful complement to conventional laboratory testing. The future utilization of POCT will depend not only on technical advances, but also on developments in costs and reimbursement.

LNSLNS

The expression “point-of-care testing” (POCT) refers to the use of the procedures of laboratory medicine in the immediate vicinity of the patient (Box 1 gif ppt). This is a recent development in laboratory medicine driven by the clinical need to obtain investigation results without delay. POCT has been facilitated by the increasing miniaturization of laboratory instruments and procedures. The key advantages of POCT are that it dispenses with sample transport to the laboratory and sample preparation. In addition, the results are immediately available at the patient’s bedside. This brings a time advantage, allowing results to inform urgent decisions about further diagnostic and therapeutic procedures. The European market for POCT systems has grown rapidly in the last ten years. The German market is now almost 0.9 billion Euros, corresponding to about a third of the total market for in vitro diagnostic testing (e1). The present review describes current diagnostic applications of POCT, together with special features which must be born in mind when applying this approach in hospitals or practices (Table 1 gif ppt). This is intended to offer the reader a critical understanding of the issues, especially the medical, organizational and economic advantages and disadvantages.

Methods

The review is based on a selective literature search, together with the first textbook on POCT in the German language (1) and additional Internet sources. The literature search covered Medline/PubMed from January 2000 to January 2009. The key words were point-of-care testing/near patient testing/bedside testing, each in conjunction with hematology/clinical chemistry/coagulation etc.. The following selection is limited to clinically important parameters measurable in blood for which there are already several different point-of-care procedures. Urine tests (e.g. pregnancy tests and drug screening) and stool tests (for example, fecal occult blood) will not be discussed. Microbiological point-of-care testing will also be omitted, as there has been a recent review on this subject in Deutsches Ärzteblatt International (2). Manufactures of diagnostic equipment or tests will not be mentioned.

Areas of use, analyses and equipment formats

Although POCT systems are mainly used in hospitals and medical practices, they are also of importance in other areas (Table 2 gif ppt). There is a large area of overlap between the areas of use and the different methods. For example, instruments to measure blood glucose and Quick/INR were originally aimed at self-monitoring, but are now also used in hospitals and practices. Lipid assays are also performed in pharmacies.

However, a test performed without a medical indication cannot be strictly described as POCT.

Blood gas and glucose analyses are long established and point-of-care assays are now available for more than 100 parameters (3).

On the other hand, no cell-related analyses beyond basic diagnostic testing (for example, identification of lymphocyte subpopulations) are available as POCT. Moreover, there are no POCT procedures which require direct expert interpretation (such as immunofluorescence). In other words, POCT is largely restricted to automatically measurable parameters. Some individual analyses are described in Box 2 (gif ppt).

The modern techniques of microfluidics and microsensorics have made it possible to develop a totally new concept of test systems and this is especially reflected in so-called “handheld” instruments. These instruments make it possible to determine one or several parameters quantitatively in different combinations, either sequentially or in parallel. One example is the determination of blood gases in combination with electrolytes or cardiac markers. These instruments have automatic calibration programs, mostly together with a control system. This monitors the analytical steps in the process and can also be used for data processing and network formation. On the other hand, table or bench top instruments can often be regarded as miniaturized forms of classical laboratory instruments. Many of these systems utilize so-called unit use reagents. This means that the reagents are provided as individual portions for each measurement and are consumed by a single test. This is particularly the case for instruments for the quantitative measurement of individual parameters, such as blood glucose, but is also used for more demanding cassette or chip systems for the simultaneous measurement of a number of parameters.

Legal conditions for licensing, operation and quality assurance

In vitro diagnostic tests—both conventional tests and POCT procedures—can only be marketed if the product has been awarded a CE mark. This confirms conformity with the European directives for in vitro diagnostic testing (IVD directive), but does not permit any statement about the test’s diagnostic reliability (18). According to the German Medical Device Regulations and the German Law on Liability, the same conditions apply to conventional laboratory analyses as to POCT. Although the test manufacturer is responsible for determining and providing the performance data, the user is responsible for checking whether performing the POCT test is suitable for its diagnostic or monitoring purpose, and technologically up to date. The latter is laid down by the legislator, the German Regulations on Medical Devices and harmonized European standards, but must always be orientated towards the objective situation (19). Thus, in an acute situation, the immediately available result from a POCT test with a high, but medically defensible, coefficient of variation may be of more benefit than a qualitatively better result which is only available on the following day (20).

The 2008 Directive of the German Medical Association on the Quality Assurance of Tests in Laboratory Medicine (RiliBÄK 2008) does not stipulate any special regulations for POCT in comparison to those for a medical laboratory, the only exception being the unit use systems (e2). Part A of the RiliBÄK contains the fundamental requirements for quality assurance, such as the preparation of a quality handbook (eBox 1 gif ppt) and applies both in hospitals and in practices. Part B1 contains the specific requirements for the quality assurance of quantitative laboratory tests; there are as yet no directives for qualitative tests (eTable 1 gif ppt). The necessary documentation is listed in eBox 2 (gif ppt).

There is also in principle no difference between POCT and conventional laboratory diagnostic testing with respect to the possibility of pre- and post-analytical errors. Thus, the whole diagnostic process must be considered in quality assurance, just as in classical laboratory medicine (eBox 3 gif ppt) (21, e2).

Application in hospitals and practices

The available analytical spectrum and the possibility of networking POCT systems and of central monitoring have made it possible to develop new approaches to clinical laboratory medicine—some of which are of doubtful value. These range from simple extension of the analytical spectrum, to transferring almost all laboratory services to an external provider with the exception of emergency analyses with POCT units.

If POCT is to be successfully implemented, it is absolutely essential that there should be suitable management structures, with clearly defined areas of responsibility (eBox 4 gif ppt) (22, e3). In hospitals, it has been found to be useful to set up a POCT coordination office, managed by the central laboratory. The main role of this is to fulfill the requirements of quality management (e3). Another condition for a successful POCT system is that there should be a computer network of the instruments in decentralized use with a central information system (for example, a hospital or laboratory information system) (Figure gif ppt) (23, 24). This may allow reliable documentation of the results, optimization of quality assurance, and proper calculation of cost-effectiveness.

On the other hand, much less effort and expense are needed when introducing POCT systems into medical practices. There are fewer emergencies here and more time pressure for organizational reasons. Patient satisfaction and compliance are more important. Thus, typical investigations performed in practices include determination of the blood count before chemotherapy, CRP measurement before antibiotic treatment, HbA1c determination in diabetics and BNP measurement when monitoring patients with heart failure. Two of the important preconditions for using POCT successfully are familiarity with the technology and proper quality assurance. This applies particularly to “real” laboratory investigations which have simply been shifted into the practice (for example, measurement of blood counts).

Medical and organizational aspects

While there are often numerous clinical studies on the medical performance of individual laboratory parameters and the technical evaluation of new POCT systems is often available in good time, there is little published data about whether the significance of a medically important laboratory parameter increases if it is measured at the bedside, or whether this is unnecessary.

One of the reasons for this is that the successful use of POCT procedures greatly depends on the setting. The critical issues in acute departments of large hospitals are not the same as those in small hospitals (for example, outsourcing, restrictions in laboratory working hours). It has for example been shown that the period that emergency patients spend in hospital outpatient departments before being admitted as inpatients, as well as the subsequent medical outcome, are independent of whether the laboratory screening took place at the POC or in the hospital laboratory. The explanation for this is that it is not the laboratory which determines the time course, but other diagnostic procedures, such as imaging, not to mention checking bed capacities (20, 25). However, the medical or organizational advantages of POCT are plausible in other cases, even without scientific proof. These include glucose determination in emergency medicine or the blood count in an oncology practice.

Cost-effectiveness

There are as yet no published cost-effectiveness analyses of POCT, in particular, not for the German-speaking area, with its special regulations on financial reimbursement of medical services. It is however generally the case that POCT procedures are markedly more expensive than conventional laboratory tests. Aside from the greater costs for the instruments and reagents, additional working hours are needed and this may have to be reflected in the number of jobs in the hospital or practice.

The fixed costs in the laboratory are often largely unchanged. There may be no fixed laboratory costs at all in a medical practice. As the POCT costs in hospital are reimbursed with the daily hospital rate or the G-DRG revenue, they must be evaluated from an objective medical point of view and also with respect to other feasible equivalent health care concepts. On the one hand, the possibility of economic and organizational improvements must be considered, for example, by optimizing the time course of work in the central laboratory or in the outpatient clinic. On the other hand, payment in medical practices largely depends on services delivered, so that the individual POCT analysis is charged for. The medical account system allows fees for POCT analyses in principle, but these reflect the real costs only in rare cases (e4, e5). This particularly applies to basic services with low reimbursement rates, which may nevertheless be essential for operating the practice in specialized areas (eTable 2 gif ppt).

Economic considerations are also relevant at a higher level. If screening with laboratory tests could reduce the use of expensive imaging procedures, this might lead to overall savings in the health system—but to a reduction in the revenue in other diagnostic disciplines.

Conclusion and outlook

A large number of laboratory tests are now available in different POCT formats, so that it is often possible to perform high quality laboratory diagnostic testing, even without a high degree of expertise in medical technology. This has allowed the development of new approaches to laboratory care in medical practices and in hospitals. Nevertheless, the justification for POCT analysis must be scrutinized in individual cases and compared with other organizational solutions, with the aim of adequately exploiting the medical potential and avoiding waste. In the interest of optimal patient care, it must also be remembered that uncritically selected and inexpertly used POCT methods cannot replace the expertise of a medical laboratory.

At first glance, the increasing use of POCT procedures appears to be in contrast to current tendencies towards centralization in laboratory medicine. However, on closer examination it becomes clear that the use of POCT can create a new balance between rapid acute on-site diagnostic testing and consolidated economic routine and special analysis in a large regional hospital laboratory or practice for laboratory medicine. Medical practices are able to offer POCT systems as an adjunct to traditional laboratory analysis. This is partly for organizational reasons, but also because practicing physicians increasingly regard themselves as service providers.

The potential of currently available tests is far from being exhausted, but POCT procedures are not spreading as rapidly in Germany as they did at first. Although there were two figure increases in the 1990s, the German POCT market only increased by 1% in 2007—in contrast to conventional laboratory testing, which increased by just under 3% in the same year (e1). One possible reason may be that service provision is simply unaffordable in some areas. Thus, to a large extent, POCT is currently an adjunct to the medical laboratory. However, in the longer term, increasing miniaturization of the technologies and more rapid measurement procedures will make it a serious alternative to conventional laboratory diagnostic testing.

Conflict of interest statement
Prof. Luppa has received lecture fees from IL, OCD, Roche, and Siemens. He has also received support for studies from Roche and Siemens. Prof. Schlebusch and Prof. Junker declare that there is no conflict of interest in the sense of the guidelines of the International Committee of Medical Journal Editors.

Manuscript received on 3 August 2009, revised version accepted on
23 November 2009.

Translated from the original German by Rodney A. Yeates, M.A., Ph.D.

Corresponding author
Prof. Dr. med. Ralf Junker
Institut für Klinische Chemie
Campus Kiel
Universitätsklinikum Schleswig-Holstein
Michaelisstr. 5
24105 Kiel, Germany

@For eReferences please refer to:
www.aerzteblatt-international.de/ref3310

eBoxes and eTables available at:
www.aerzteblatt-international.de/10m0561

1.
Luppa PB, Schlebusch H (eds.): POCT – Patientennahe Labordia-gnostik. Heidelberg: Springer Medizin Verlag, 2008.
2.
Stürenburg E, Junker R: Point-of-care testing in Microbiology [Patientennahe Diagnostik in der Mikrobiologie: Chancen und Risiken immunchromatografischer Teststreifen]. Dtsch Arztebl Int 2009; 106(4): 48–54 VOLLTEXT
3.
Price CP, Kricha LJ: Improving health care acceessibility through point-of-care technologies. Clin Chem 2007; 53: 1665–75. MEDLINE
4.
Kristensen GBB, Christensen NG, Thue G, Sandberg S: Between-lot variation of external quality assessment of glucose: clinical importance and effect on participant performance evaluation. Clin Chem 2005; 51: 1632–6. MEDLINE
5.
Koschinsky T, Wahl HG: Glukosebestimmung und Diabetesdiagnostik mittels POCT. In: Luppa PB, Schlebusch H. POCT-Patientennahe Labordiagnostik. Heidelberg: Springer Medizin Verlag, 2008: 253–66.
6.
Boncheva M, Pascaleva I, Dineva D: Performance of POCT-chemistry analyzer Picollo (Abaxis) in primary health care. Gen Med 2002; 4: 28–31.
7.
Price CP, Koller PU: A multicentre study of the new Reflotron system for the measurement of urea, glucose, triacylglycerols, cholesterol, gamma-glutamyltransferase and haemoglobin. J Clin Chem Clin Biochem 1988; 26: 233–50. MEDLINE
8.
Dahler-Eriksen BS, Lauritzen T, Lassen JF, Lund ED, Brandslund I: Near-patient test for C-reactive protein in general practice: assessment of clinical, organizational, and economic outcomes. Clin Chem 1999; 45: 478–85. MEDLINE
9.
Nola KM, Gourley DR, Portner TS, et al.: Clinical and humanistic outcomes of a lipid management program in the community pharmacy setting. J Am Pharm Assoc 2000; 40: 166–73. MEDLINE
10.
Thaler M, Luppa P, Schlebusch H: Die Bilirubinbestimmung – Eine aktuelle Übersicht. J Lab Med 2008; 32: 1–10.
11.
van Solinge WW, Huisman A: Point-of-care testing in haematology. In: Price CP, St John A, Hicks JM (eds.): Point-of-care testing, 2nd edition. Washington, DC: AACC Press, 2004: 415–20.
12.
Walters MC, Abelson HT: Interpretation of the complete blood count. Pediatr Clin North Am 1996; 43: 599–622. MEDLINE
13.
Spannagl M, Calatzis A: Point-of-Care Analyse des Hämostasesystems. J Lab Med 2002; 26: 68–76.
14.
The Joint European Society of Cardiology/American College of Cardiology Committee: MEDLINE Myocardial infarction redefined – A consensus document of The Joint European Society of Cardiology/American College of Cardiology Committee for the Redefinition of Myocardial Infarction. Eur Heart J 2000; 21: 1502–13.
15.
Peetz D, Hafner G, Lackner KJ: Patientennahe Bestimmung natriuretischer Peptide. J Lab Med 2005: 29; 219–28.
16.
AWMF online: Diagnostik und Therapie der Bein- und Beckenvenenthrombose und Lungenembolie. Leitlinien Angiologie,
www.leitlinien.net, 2008.
17.
Briedigkeit L, Müller-Plathe O, Schlebusch H, Ziems J: Patientennahe Laboratoriumsdiagnostik (Point-of-care Testing): 1. Empfehlungen der Arbeitsgemeinschaft Medizinische Laboratoriumsdiagnostik (AML) zur Einführung und Qualitätssicherung von Verfahren der patientennahen Laboratoriumsdiagnostik (POCT). J Lab Med 1998; 22: 414–20.
18.
Nübling M: CE-Kennzeichnung von Point-of-care-Testsystemen.
J Lab Med 2006; 30: 226–9.
19.
Meyer-Lüerßen D, Meyer-Lüerßen I: Rechtssicherheit von Point-of-Care-Tests. J Lab Med 2006; 30: 230–3.
20.
Schlüter B, Junker R: Labordiagnostik – Schneller ist nicht immer besser. Dtsch Arztebl 2003; 100(9): A 87–9. VOLLTEXT
21.
Guder WG, Ehret W, da Fonseca-Wollheim F, et al.: Die Qualität diagnostischer Proben. Empfehlungen der Arbeitsgruppe Präanalytik der Deutschen Gesellschaft für Klinische Chemie und der Deutschen Gesellschaft für Laboratoriumsmedizin. J Lab Med 2002; 26: 267–83.
22.
Hänecke P, Haeckel R, Koschinsky T, Luppa P, Schlebusch H, Wahl HG: Qualitätssicherung der patientennahen Sofortdiagnostik (Point-of-Care Testing) im Krankenhaus: Muster für eine hausinterne Richtlinie. J Lab Med 2004; 28: 256–63.
23.
Messner B, Frick G, Blobner M, Albrecht K, Schade T, Luppa PB: Online-Qualitätssicherung patientennaher Sofortdiagnostik (Point-of-Care-Testing) unter Nutzung des Kommunikations-Systems des Krankenhauses. J Lab Med 2004; 28: 264–72.
24.
Luppa PB, Gässler N, Haeckel R, et al.: Stellungnahme der Arbeitsgemeinschaft „Point-of-care Testing“ der DGKL zum Thema Vernetzung von POCT-Geräten im Krankenhaus mit Zentrallabor. J Lab Med 2005; 29: 241–5.
25.
Kilgore ML, Steindel SJ, Smith JA: Evaluating stat testing options in an academic health center. Therapeutic turnaround time and staff satisfaction. Clin Chem 1998; 44: 1597–603. MEDLINE
e1.
Deutscher Verband der Diagnostica-Industrie e.V. (VDGH): www.vdgh.de, 2009.
e2.
Bundes­ärzte­kammer: Richtlinie der Bundes­ärzte­kammer zur Qualitätssicherung laboratoriumsmedizinischer Untersuchungen. Dtsch Arztebl 2008; 105(7): A 341–55. VOLLTEXT
e3.
Gässler N, Luppa PB, Hafner G, et al.: Information der Arbeitsgemeinschaft „Point-of-Care Testing“ der DGKL: Einführung von POCT innerhalb einer Klinik. Klinische Chemie Mitteilungen 2006; 37: 161–3.
e4.
Kassenärztliche Bundesvereinigung. Einheitlicher Bewertungsmaßstab (EBM). http://www.kbv.de/ebm2009/EBMGesamt.html, 2009.
e5.
Gebührenordnung für Ärzte (GOÄ). Deutscher Ärzte-Verlag, 2001.
Institut für Klinische Chemie, Universitätsklinikum Schleswig-Holstein: Prof. Dr. med. Junker
Institut für Klinische Chemie und Pathobiochemie, Klinikum rechts der Isar der TU München: Prof. Dr. med. Schlebusch, Prof. Dr. med. Luppa
1.Luppa PB, Schlebusch H (eds.): POCT – Patientennahe Labordia-gnostik. Heidelberg: Springer Medizin Verlag, 2008.
2.Stürenburg E, Junker R: Point-of-care testing in Microbiology [Patientennahe Diagnostik in der Mikrobiologie: Chancen und Risiken immunchromatografischer Teststreifen]. Dtsch Arztebl Int 2009; 106(4): 48–54 VOLLTEXT
3.Price CP, Kricha LJ: Improving health care acceessibility through point-of-care technologies. Clin Chem 2007; 53: 1665–75. MEDLINE
4.Kristensen GBB, Christensen NG, Thue G, Sandberg S: Between-lot variation of external quality assessment of glucose: clinical importance and effect on participant performance evaluation. Clin Chem 2005; 51: 1632–6. MEDLINE
5.Koschinsky T, Wahl HG: Glukosebestimmung und Diabetesdiagnostik mittels POCT. In: Luppa PB, Schlebusch H. POCT-Patientennahe Labordiagnostik. Heidelberg: Springer Medizin Verlag, 2008: 253–66.
6.Boncheva M, Pascaleva I, Dineva D: Performance of POCT-chemistry analyzer Picollo (Abaxis) in primary health care. Gen Med 2002; 4: 28–31.
7.Price CP, Koller PU: A multicentre study of the new Reflotron system for the measurement of urea, glucose, triacylglycerols, cholesterol, gamma-glutamyltransferase and haemoglobin. J Clin Chem Clin Biochem 1988; 26: 233–50. MEDLINE
8.Dahler-Eriksen BS, Lauritzen T, Lassen JF, Lund ED, Brandslund I: Near-patient test for C-reactive protein in general practice: assessment of clinical, organizational, and economic outcomes. Clin Chem 1999; 45: 478–85. MEDLINE
9.Nola KM, Gourley DR, Portner TS, et al.: Clinical and humanistic outcomes of a lipid management program in the community pharmacy setting. J Am Pharm Assoc 2000; 40: 166–73. MEDLINE
10.Thaler M, Luppa P, Schlebusch H: Die Bilirubinbestimmung – Eine aktuelle Übersicht. J Lab Med 2008; 32: 1–10.
11.van Solinge WW, Huisman A: Point-of-care testing in haematology. In: Price CP, St John A, Hicks JM (eds.): Point-of-care testing, 2nd edition. Washington, DC: AACC Press, 2004: 415–20.
12.Walters MC, Abelson HT: Interpretation of the complete blood count. Pediatr Clin North Am 1996; 43: 599–622. MEDLINE
13.Spannagl M, Calatzis A: Point-of-Care Analyse des Hämostasesystems. J Lab Med 2002; 26: 68–76.
14.The Joint European Society of Cardiology/American College of Cardiology Committee: MEDLINE Myocardial infarction redefined – A consensus document of The Joint European Society of Cardiology/American College of Cardiology Committee for the Redefinition of Myocardial Infarction. Eur Heart J 2000; 21: 1502–13.
15.Peetz D, Hafner G, Lackner KJ: Patientennahe Bestimmung natriuretischer Peptide. J Lab Med 2005: 29; 219–28.
16.AWMF online: Diagnostik und Therapie der Bein- und Beckenvenenthrombose und Lungenembolie. Leitlinien Angiologie,
www.leitlinien.net, 2008.
17.Briedigkeit L, Müller-Plathe O, Schlebusch H, Ziems J: Patientennahe Laboratoriumsdiagnostik (Point-of-care Testing): 1. Empfehlungen der Arbeitsgemeinschaft Medizinische Laboratoriumsdiagnostik (AML) zur Einführung und Qualitätssicherung von Verfahren der patientennahen Laboratoriumsdiagnostik (POCT). J Lab Med 1998; 22: 414–20.
18.Nübling M: CE-Kennzeichnung von Point-of-care-Testsystemen.
J Lab Med 2006; 30: 226–9.
19.Meyer-Lüerßen D, Meyer-Lüerßen I: Rechtssicherheit von Point-of-Care-Tests. J Lab Med 2006; 30: 230–3.
20.Schlüter B, Junker R: Labordiagnostik – Schneller ist nicht immer besser. Dtsch Arztebl 2003; 100(9): A 87–9. VOLLTEXT
21.Guder WG, Ehret W, da Fonseca-Wollheim F, et al.: Die Qualität diagnostischer Proben. Empfehlungen der Arbeitsgruppe Präanalytik der Deutschen Gesellschaft für Klinische Chemie und der Deutschen Gesellschaft für Laboratoriumsmedizin. J Lab Med 2002; 26: 267–83.
22.Hänecke P, Haeckel R, Koschinsky T, Luppa P, Schlebusch H, Wahl HG: Qualitätssicherung der patientennahen Sofortdiagnostik (Point-of-Care Testing) im Krankenhaus: Muster für eine hausinterne Richtlinie. J Lab Med 2004; 28: 256–63.
23.Messner B, Frick G, Blobner M, Albrecht K, Schade T, Luppa PB: Online-Qualitätssicherung patientennaher Sofortdiagnostik (Point-of-Care-Testing) unter Nutzung des Kommunikations-Systems des Krankenhauses. J Lab Med 2004; 28: 264–72.
24.Luppa PB, Gässler N, Haeckel R, et al.: Stellungnahme der Arbeitsgemeinschaft „Point-of-care Testing“ der DGKL zum Thema Vernetzung von POCT-Geräten im Krankenhaus mit Zentrallabor. J Lab Med 2005; 29: 241–5.
25.Kilgore ML, Steindel SJ, Smith JA: Evaluating stat testing options in an academic health center. Therapeutic turnaround time and staff satisfaction. Clin Chem 1998; 44: 1597–603. MEDLINE
e1.Deutscher Verband der Diagnostica-Industrie e.V. (VDGH): www.vdgh.de, 2009.
e2.Bundes­ärzte­kammer: Richtlinie der Bundes­ärzte­kammer zur Qualitätssicherung laboratoriumsmedizinischer Untersuchungen. Dtsch Arztebl 2008; 105(7): A 341–55. VOLLTEXT
e3.Gässler N, Luppa PB, Hafner G, et al.: Information der Arbeitsgemeinschaft „Point-of-Care Testing“ der DGKL: Einführung von POCT innerhalb einer Klinik. Klinische Chemie Mitteilungen 2006; 37: 161–3.
e4.Kassenärztliche Bundesvereinigung. Einheitlicher Bewertungsmaßstab (EBM). http://www.kbv.de/ebm2009/EBMGesamt.html, 2009.
e5.Gebührenordnung für Ärzte (GOÄ). Deutscher Ärzte-Verlag, 2001.