Can splitting the blood sample for photometric chemical assay and immunoassay reduce turnaround time for chemical assay?

INTRODUCTION

The “quality” of a laboratory is defined as its ability to satisfy the consumers’ expectations, focusing on the precision and accuracy of reports in the laboratory.^[1] For decision-making, timeliness is an important indicator of quality to a clinician, which may be overlooked by clinical biochemists for technical or analytical intricacies.^[2] Turnaround time (TAT), total or therapeutic, can be described as the time from “vein to brain” or “brain to brain,” i.e., from test requisition to therapeutic decision-making.^[3] The testing process can be divided into three phases, namely pre-analytical (from requisition of test/receipt of sample to its preparation), analytical (actual testing), and post-analytical (verification/printing/dispatch/interpretation of results), upon which TAT depends.^[4,5] It is important to balance the “faster is better” approach with the accuracy and precision of reports, and various strategies can help shorten the steps in the TAT cycle.^[6,7]

There are integrated systems that incorporate photometry-based chemical assays with enhanced chemiluminescence-based immunoassays on the same platform. When many such systems are attached to an efficient track system and controlled by the Laboratory Information System (LIS), it eliminates the need to split samples for photometry-based chemical assays and chemiluminescence-based immunoassays. This capability of independently processing a high sample volume/load helps in the efficient utilization of space and aims to improve TAT by quicker patient reporting.^[8,9]

Despite the high throughput of such a track system controlled by LIS, the change in TAT was not as expected for the samples that need both photometry-based chemical assays and chemiluminescence-based immunoassays. It was felt that the use of a track system, per se, may be the cause of the increased time of the analytical phase, or else when both photometry-based chemical assays and immunoassays are done from a single sample, it results in an increase in time required at the analytical phase leading to increase in TAT. To check this hypothesis, this study was designed to assess whether,

1. By introducing samples separately (for photometry-based chemical tests and chemiluminescence-based immunoassays) in the analyzer, we can decrease TAT

2. By avoiding the use of the track and using the standalone system, the TAT can be improved.

MATERIALS AND METHODS

The study was an experimental study conducted in the Biochemistry laboratory of a tertiary care hospital in Delhi, India. Patient consent/ethical clearance was not obtained as no patient data/information was used for the study.

RESULTS

The mean time and SD in the analytical phase for all three scenarios are presented in Table 1.

All three scenarios are as follows: Mean time in the analytical phase in (a) single sample for all tests using the track, (b) separate samples for photometry-based chemical tests and chemiluminescence-based immunoassay using the track, and (c) standalone samples for each without using track (n = 40 in each group).

DISCUSSION

The timeliness of laboratory services to patients and clinicians is an important determinant of laboratory quality, together with accuracy and precision.^[3] TAT has come up to become a cornerstone of laboratory efficiency in recent times, and it is the prerogative of laboratory managers to ensure timeliness. Despite making significant technical, transport, and information-technology advancements in recent years, TAT continues to be a cause of consumer dissatisfaction with laboratory services. Laboratory staff are kept on their toes, trying to balance these factors. ^[10,11]

As shown in Table 1, the average time in the analytical phase for the photometry-based chemical tests was observed to be lesser than that of chemiluminescence-based immunoassays, irrespective of the type of intervention made. This was despite the number of immunochemiluminescence-based tests (5/sample) being lesser than photometry-based chemical tests (9/sample). This could be attributed to the longer incubation period with antibodies in immunochemiluminescence methods, as has been documented by other studies performed both by the manufacturer of the equipment and users.^[8,9] Owing to this, chemiluminescence-based immunoassay tests become one of the deciding factors for TAT.

As shown in Table 1, when a single sample was run for photometry-based chemical and chemiluminescence-based immunoassays using the track controlled by LIS, the mean time for photometry-based chemical tests was 100 min (SD = 58.9) and that for chemiluminescence-based immunoassay parameters was 211 min (SD = 106.5). However, as LIS generates a single report when the system completes all the tests, the mean time for analysis of both photometry-based chemical tests and chemiluminescence-based immunoassays turns out to be 211 min, although the system completes the photometry-based chemical assays on average 100 min. In the second scenario “(b),” when separate samples for photometry-based chemical and chemiluminescence-based immunoassays were run using the track system controlled by LIS, the average assay time for photometry-based chemical assays was 136 min (SD 80.9) which was less than that 211 min when a common sample was used for both photometry-based chemical and chemiluminescence-based immunoassays. Although processing samples in different vials for different tests is more time and resource-consuming, the TAT for reporting photometry-based chemical tests can be significantly decreased. A number of factors came into play with the use of the automation track, like the number of samples (increased further as separate samples were taken for photometry-based chemical tests and chemiluminescence-based immunoassays), crowding the track. Furthermore, any failure or breakdown of equipment, as often occurs in laboratory settings, can lead to a further increase in TAT. In view of this, we infer that by splitting the samples for photometry-based chemical tests and chemiluminescence-based immunoassays or by acquiring two different samples for each, we may be able to reduce the TAT for photometry-based chemical assays and report them earlier. This is crucial because photometry-based chemical test reports are more often used in clinical decision-making in emergencies and wanted by the treating physician as early as possible, whereas chemiluminescence-based immunoassays are not often needed urgently (except in some rare situations like a hypothyroid coma). Hence, we recommend the splitting of the samples for photometry-based chemical and chemiluminescence-based immunoassays or acquiring two different samples for each from the source, particularly for patients admitted to intensive care and high dependency units (ICU/HDU). Alternatively, LIS may be improved in such a way that the system will generate separate reports for photometry-based chemical tests (that can be taken/dispatched as soon as these tests are complete) and chemiluminescence-based immunological tests.

In the third scenario “(c),” when separate samples for photometry-based chemical and chemiluminescence-based immunoassays were used analyzed in a standalone equipment (capable of performing all assays), bypassing the automation track and LIS, the mean time required during analysis phase was 61 min (SD = 43.8) for photometry-based chemical tests and 145 min (SD = 71.4) for chemiluminescence-based immunoassay parameters, that was far less than that in the first and second situations. This observation refutes the very fundamental essence of the automation track and LIS in reducing TAT in laboratory set up. However, despite this observation, we do not recommend using a LIS-regulated track-based system attaching multiple auto analyzers on track, as it reduces the manpower and space requirement and performs many other functions, reducing the final TAT. In this study, those things were not factored in. Another limitation of the study includes the fact that the samples sent into the track following our study samples may have affected the order of processing of some of the study samples due to the organization of the track. Furthermore, such a specific type of study design tailored for one laboratory may not be directly applicable to many.

CONCLUSIONS

Hence, we conclude that there is a need to develop an LIS that can segregate the reports of photometry-based chemical and chemiluminescence-based immunoassay tests even when performed from a single sample, and, till such a development occurs, separate samples for photometry-based chemical tests and chemiluminescence-based immunoassays should be introduced in such a system for patients admitted, particularly to ICU and HDU.