Despite the growing popularity, the level of reliability of results from point-of-care tests has been found to be lower than results of centralized laboratory tests. In one series of tests, Karon et al. [7] established the existence a higher risk of false results from point-of-care tests, which could lead to wrong prognosis or medical errors.
Hawkins [8] observes that although the level of precision achieved using the common point-of-care platforms (Biorad Diastat, Drew DS5, Bayer DCA 2000 and Nycomed Nycocard) varies noticeably, none of the point-of-care technology systems matches the level of precision achieved in the centralized laboratory. According to Hawkins [8], the DS5 and Nycocard systems exhibit very poor precision compared to DCA 2000 and Diastat. There are difficulties which accompany any attempts at comparing POCT and centralized laboratory results.
A leading factor is that unlike POC tests, laboratory results and performance are evaluated in relative terms, rather than absolute terms. Laboratory results are often compared to results from other laboratories so that resulting values are classified as normal or abnormal based on how much they vary from the mean of test results from hundreds of laboratories [12]. Causes of the reduced reliability of POC Tests Several reasons have been identified as the major causes of discrepancies in reliability between POCT and laboratory testing results. Top of this list is the “lack of quality assurance, quality control and management programs” [5].
For decades, laboratory professionals have developed and employed quality assurance and control mechanisms to govern their practice and ensure patient safety. Laboratory professionals are highly trained and required to refresh and update their skills continuously. On the other hand, POCT staffs were neither required to be qualified for laboratory medicine nor required to be trained further. Research has shown that “there are twice as many analytical errors in POCT in comparison with the error rate in centralized testing” [5], and poor quality control may have contributed to this.
According to Serio, Petronelli & Sammartino [10], the short turn-around time and medical implications can actually heighten the risk to the patient. It is only in the last decade that quality and competence structures have been implemented to govern the use of point-of-care technologies. Thus, whenever there are critical decisions to be made about the patient, health-care professionals are advised to use results from centralized laboratory tests [11]. Another cause of the discrepancies between point-of-care and centralized laboratory test results is the use of plasma in one and serum in the other.
When indirect point-of-care test devices are used, potassium values are significantly and consistently higher in serum than in plasma. This happens because some potassium is released and lost during the clotting process [11]. While discrepancies resulting from air-contamination of the samples and clotting may not be blamed on the POCT professionals, it is their responsibility to know how to deal with the discrepancies and act accordingly. Improving the performance of point-of-care tests and technologies
Without doubt, point-of-care technology will stay and its popularity can only rise in the face of increased demand for health-care services, insufficient health-care resources, and higher cost-consciousness among health-care consumers. There is therefore a critical need to improve the precision and suitability of POCT systems to make their use safer. An essential step towards increased reliability of POC technologies should entail developing and implementing stringent quality assurance and control mechanisms to govern the use of POC tests.
There should be standardized training for health-care professionals employing POC tests. Patients using POC technologies should be adequately trained on how to use and handle the test devices, and how to interpret the test results. Independent quality control and assurance bodies should be created and given the power and resources to regulate the use of POC technologies. There is need, in the interest of patient safety, to link POC tests to a reference centralized laboratory [10].
As noted above, POC tests are not intended and should not replace centralized laboratory tests as results from the latter tend to be more reliable. Putting POC test procedures under a reference laboratory ensures that the process is conducted in accordance with the rigorous quality assurance structures which govern laboratory medicine. It also provides the opportunity for health-care professionals to compare POCT results with centralized laboratory results, particularly when a serious medical decision is to be made. Conclusion POC technologies have revolutionized health-care provision.
Fast-growing popularity of these technologies is testimony to their benefits to both patients and health-care professionals. However, POC systems have been plagued by challenges including less reliability and precision, and lack of quality regulation mechanisms. These challenges are common with new innovations and are not entirely unique to POC technologies. POCT technology developers have the opportunity to improve the reliability of these technologies. The ease of access and use of POC technologies should however not form the basis of any ideas in favor of replacing laboratory testing with POC testing.
The two should be used together in such a manner as to increase patient safety. Reference List 1. Ehrmeyer SS & Laessig RH. Point-of-Care Testing, Medical Error, and Patient Safety: A 2007 Assessment. Clinical Chemistry & Laboratory Medicine 2007; 45(6): 766-773. 2. Sickels J, Lafata JE & Ansell JE. Point-of-Care Testing in Oral Anticoagulant Monitoring. Dis Manage Health Outcomes 1999; 6(5): 291-301. 3. Haglund S. , Transo B. , Person L, Zafirova T & Grodzinsky E. Fast Laboratory Test Results
Alone Cannot Deliver the Benefits of Near Patient Testing: A Follow-up Study After 3 Years of Extended Laboratory Service at a Primary Health Care Centre. Journal of Evaluation in Clinical Practice 2009; 15: 227-233. 4. Lee-Lewandrowski E. , Corboy D. , Lewandrowski K. , Sinclair J. , McDermot S & Benzer TI. Implementation of a Point-of-Care Satellite Laboratory in the Emergency Department of an Academic Medical Center. Archives of Pathology & Laboratory Medicine 2003; Vol. 127: 456-460. 5. Schimke I. Quality and Timeliness in Medical Laboratory Testing. Annal Bioanal Chem 2009; 393: 1499-1504.