Comparative Performance of POCT and Central Laboratory Testing

Abstract

Diagnosis is undoubtedly one of the most important components of healthcare delivery whether performed through POCT or central laboratory testing. This is attributed to the fact that many medical or patient treatment decisions are dependent on the results of either POCT or central laboratory testing. Recent technological advancements have continued to increase the use of POCT. However, despite the results reliability, quality control and performance issues discussed in this essay, the importance of POCT in emergency departments, wards and intensive care units cannot be underestimated. It has also been observed that central laboratory testing is far much better in terms results reliability, quality control and performance compared to POCT which is liked for its convenience, flexibility and time effectiveness. However, the performance of the POCT personnel can be significantly improved if POCT personnel are in possession of required skills and appropriate quality control procedures are strictly adhered to by all the staffs involved in POCT.

Introduction

Diagnosis is undoubtedly one of the most important components of healthcare delivery. This is attributable to the fact that whether conducted the central laboratory or at a satellite location, it is usually heavily relied on by physicians to evaluate the application of the available treatment alternatives and make decisions [1, 2]. Thus, diagnosis may either be done on the basis of point-of-care testing (POCT) or central laboratory testing. Throughout the last century, healthcare delivery has continued to evolve from being home-based service to one that is provided in hospitals that are increasingly centralized depending on the complexity of the illness [3]. Additionally, laboratory services that aid the diagnosis of diseases has also followed the same route, beginning with simple tests that were conducted at the bedside eventually developing into a comprehensive healthcare service performed in facilities outside or within the hospitals that are centralised [4,5].

However, for the last several decades it has also been possible to move testing back closer to patients, referred to as POCT due to continuing technological advancements that have led to production of smaller diagnostic devices that easy to transport and suitable for use in an environment outside the laboratory [5, 6, 7]. Moreover, central laboratory testing remains the most appropriate diagnostic option, but the challenge of its inability to be applied in scenarios outside the laboratory makes the use of other alternatives such as the POCT essential. Therefore, both POCT and central laboratory testing have been collaboratively used to ensure there is effective delivery of healthcare services which is dependent on accurate diagnosis on the basis of preset standards [3, 8].

Why the POCT are often considered unreliable compared to central laboratory testing and the possible performance issues with some forms of POCT technology

Generally, the tests performed through central laboratory testing are often considered more reliable that those performed using POCT. This is due to the fact that POCT results can be significantly affected by pre-analytical variables such as haemolysis (especially when testing electrolyte concentrations such as potassium), inadequate specimen mixing with anticoagulant, fibrin clots within the specimen and varying the ratio of anticoagulant to blood sample [9, 10]. There is also another reason which makes the results of POCT to be considered unreliable is blood sample contamination by ambient air [2, 5].

Moreover, POCT as opposed to central laboratory testing are performed using simple and unsophisticated diagnostic devices while central laboratory testing are performed using larger, sophisticated and more complex diagnostic devices that are very accurate and precise [11]. However, even though this difference may not be clinically significant, it may however pose a great challenge in terms of quality control, assurance and management as well as when making reference to the set standards.

Moreover, the results of POCT are not mostly used in the central laboratory testing database for quality control, assurance and management and many staffs involved in performing POCT are often not aware of the essence of quality control as well as proper procedure to be followed if controls fail [12, 13]. This is mainly because anyone in an hospital setting can perform POCT ranging from nurses to physicians to paramedics can perform POCT, as opposed to central laboratory testing which is performed by qualified medical laboratory staff. Therefore, in case controls fail and necessary corrective actions are not taken, which is a regular phenomenon in POCT, then all subsequent patient test results derived from the diagnostic device used to perform POCT are invalid [8, 9, 14].

Moreover, there are various possible performance issues with some forms of POCT technology even though its fitness for purpose is acknowledgeable. This is mainly because most forms of POCT technology are considered to provide life-saving preliminary results that are time dependent compared to central laboratory testing which is considered to provide critical patient results [15]. The POCT diagnostic devices are usually small and easy to carry around, but their accuracy and precision is not often comparable with those used in central laboratory testing [12, 15]. Moreover, blood samples used in POCT may be contaminated leading to skewed results. Irrespective of these performance issues with POCT, they have significant role in timely provision of diagnostic results in wards, emergency departments and intensive care units [2, 8].

Problems with direct comparison of POCT and central laboratory results and the possible reasons for discrepancies between POCT and central laboratory results

Direct comparison of POCT and central laboratory results is not always essential because the former is meant to bring the test conveniently and timely to the patient, thus increasing the chance for the physician, patient, and care team to obtain the test results quicker leading to making of immediate clinical management decisions [12, 16]. However, the latter is not only meant for diagnosis, but also quality control and assurance. Moreover, the reasons for discrepancies between POCT and central laboratory results is mainly because of the diagnostic devices used, staff performing both tests and the location of performing both tests [5, 8, 10, 17].

Skill requirements for POCT personnel

POCT personnel are not supposed to possess specialized skills, but they are required to have the ability to effectively operate the involved diagnostic devices including calibration and troubleshooting. POCT personnel are also required to have the skills of obtaining testing samples from patients [18].

Sample quality and POCT performance

Often sample quality in POCT is poor due to the influence of pre-analytical variables such as haemolysis (especially when testing electrolyte concentrations such as potassium), inadequate specimen mixing with anticoagulant, fibrin clots within the specimen and varying the ratio of anticoagulant to blood sample. This considerably affects the performance of POCT making its result to be considered not as reliable as those obtained from central laboratory testing [7, 12].

However, despite the fact that POCT performance can be influenced by sample quality, it is also essential to make sure that the POCT performance assessment is performed regularly. This can be achieved through regular calibration of the POCT diagnostic devices and running of controls. This could help in addressing quality control and proficiency testing issues for POCT [10, 14].

Measurement uncertainty for POCT and central laboratory results, and the impact on result interpretation

The variations observed in the POCT and central laboratory results; this has led to measurement uncertainty for POCT and central laboratory results. However, despite the fact that in terms of quality control these differences are significant, it is however that the results from both are not clinically significant and both can be used by the physician to make medication decisions [12, 18]. This implies that this measurement uncertainty has impact on result interpretation since POCT results are considered preliminary, whereas central laboratory testing results are considered critical and final. Thus, when POCT results are being interpreted the physician often gives an allowance [19].

Procedures by which improved performance of POCT can be achieved

Improved POCT performance can be achieved by various procedures. For instance, POCT personnel are supposed to have the ability to the operate POCT devices and to collect samples from patients [7, 20]. Moreover, prior to performing POCT, the diagnostic devices used should be calibrated for effective quality control and whenever a control fails, the POCT staff should inform the appropriate central laboratory staff which helps creates chance for the procedural steps review with POCT staff [12, 17]. Finally, continuous medical education between central laboratory and POCT staff through seminars and training programs should be embraced ultimately resulting to a better educated point of care team [17].

Conclusion

In conclusion it is undoubtedly clear that no healthcare facility which can effectively deliver healthcare services without a functioning POCT team. However, despite the results reliability, quality control and performance issues highlighted the importance of POCT in emergency departments, wards and intensive care units cannot be underestimated. It is also evident that central laboratory testing is by far much better than POCT other than the convenience, flexibility and time effectiveness of the latter.

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