Background

Conclusion

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Comparison of Reactive Rates Between EIA and Chemiluminescent Donor Screening

Assays G. Martinez, N. Haubert, G. Leparc, P. Williamson, R. Spizman, G. Robertson, S. Caglioti,

Creative Testing Solutions, a large national

donor testing laboratory changed its supplier

of screening immunoassays for infectious

diseases (Viral Markers or VMs) during the

month of July in 2013. The new VMs

generate chemiluminescence signals

(ChLIA) to detect the targeted molecules.

Repeat reactive rates (RRR) and, when

applicable, confirmatory rates (CR) of VMs

were compared between Enzyme-Linked

Immunosorbent Assay (EIA) and ChLIA for a

period of six months before and after the

change in suppliers to assess comparative

performance and associated culling effect

on blood donors.

CTS observed differences in the RRR

performance of VMs with the two different

technologies. Only the HCV assays had

similar RRR and percentage of CR.

Four of the five ChLIA VM assays

demonstrated lower RRR than EIA.

The ChLIA HIV assay had a higher RRR

and a lower percentage of CR than the

corresponding EIA..

The combined VM results from the ChLIAs

are expected to result in 9 fewer

unnecessary discarded donations per

10,000 donations tested as compared to

the EIAs.

Given the 13.8% decrease in the HIV RRR

between the first and the sixth month of use

for the ChLIAs, we anticipate continued

improvement in the total RRR compared to

EIA, as culling of false positive donors is

completed.

Methods Viral Marker RRRs and CRs were

calculated from a volume of at least 2

million samples received from across the

country over the six months period of time

before the change in supplier and over the

six months period of time immediately after

the change.

This comparison primarily focused on VMs

required to be performed on every donation.

T. cruzi was not fully included in this report

because it is only performed on donors who

presumably donated for the first time and

they would not help us see if and to what

degree the performance of the ChLIA assay

improved over time as the population of EIA

tested donors was culled by the new

methodology. However, representative EIA

and ChLIA rates will be briefly listed in the

results section.

A decrease of 0.093% in the combined RRR

with the ChLIA VM assays was observed by

CTS for every donation as compared to the

RRR of the corresponding set of required

EIA VM assays. The difference in the total

RRRs represents approximately 9 fewer

discarded donations per 10,000 donations

tested with the ChLIAs as compared to the

EIAs.

RRR Table for the Five Required VMs

EIA ChLIA ChLIA- EIA

VM Assay RRR CR RRR CR RRR CR

HIV 1 / 2 0.038% 30.2% 0.103% 9.6% 0.065% -20.6%

HCV 0.152% 56.8% 0.148% 55.1% -0.004% -1.7%

HBsAg 0.083% 27.8% 0.032% 64.1% -0.051% 36.3%

HBc 0.483% N/A 0.435% N/A -0.048% N/A

HTLV I / II 0.098% 13.0% 0.043% 26.2% -0.055% 13.2%

Sum 0.854% 0.761% -0.093%

Changes in VM Confirmed Results

During the Study Period

0%

5%

10%

15%

20%

25%

30%

35%

40%

Percent of Repeat Reactive HIV 1/2 Samples that Were

Positive with a Confirmatory Assay

0%

5%

10%

15%

20%

25%

30%

35%

Percent of Repeat Reactive HTLV I/II Samples that

Were Positive with a Confirmatory Assay

0%

10%

20%

30%

40%

50%

60%

70%

80%

Percent of Repeat Reactive HBsAg Samples that Were

Positive with a Confirmatory Assay Results

0%

10%

20%

30%

40%

50%

60%

70%

Percent of Repeat Reactive HCV Samples that Were

Positive with a Confirmatory Assay

T. Cruzi EIA ChLIA

RRR 0.017% 0.079%