Creative Testing Solutions changed its supplier of screening assays for infectious diseases from enzyme-linked immunosorbent assays (EIA) to chemiluminescence assays (ChLIA) in July 2013. They compared the repeat reactive rates (RRR) and confirmatory rates (CR) between the two methods using over 2 million samples in the 6 months before and after the change. They found that four of the five ChLIA assays had lower RRR than the EIA counterparts, with the HIV ChLIA having a higher RRR but lower CR. Overall, the ChLIA assays were expected to result in 9 fewer unnecessary discarded donations per 10,000 tested compared to the EIA assays due to lower R

1. 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%