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Investigational Site 4 assessed sensitivity for past infection with sera from
patients who exhibited no signs or symptoms of disease but were HI positive.
Focus IgG ELISA Sensitivity with Past Infection Sera (Site 4)
Condition Sensitivity 95% CI
Endemic HI Positive* 39%* (13/33) 22.9-57.9%
Dengue Virus IgG DxSelect Kit
Product Code: EL1500G
Rev. F
Performance Characteristics
Not for Distribution in the United States
SENSITIVITY
Investigational Site 1 assessed sensitivity by assaying well characterized sera.
Each sera was:
1) drawn from patients exhibiting dengue fever (DF) or dengue hemorrhagic
fever (DHF) symptoms,
2) the patient’s initial primary draw,
3) drawn within 1 to 16 days of onset, and
4) previously confirmed as infected with dengue virus by ELISA, HI and/or
PCR.
Focus IgG ELISA Sensitivity with Acute Sera (Site 1)
Condition Sensitivity 95% CI
DF 98% (49/50) 89.4-99.9%
DHF 93% (27/29) 77.2-99.2%
Overall 96% (76/79) 89.3-99.2%
Investigational Site 2 assessed sensitivity by assaying paired sera (n = 34)
from 17 patients suspected as being infected with dengue virus. Each patient
was drawn at onset and 7 to 10 days post onset. The investigator assayed the
sera using the product and the investigator's IgG ELISA.
Sensitivity with Paired Acute Sera (Site 2)
Device Time Post Onset Sensitivity 95% CI
Focus ELISA 0 days 100% (17/17) 80.5-100%
Focus ELISA 7-10 days 100% (17/17) 80.5-100%
Investigator's ELISA 0 days 100% (17/17) 80.5-100%
Investigator's ELISA 7-10 days 100% (17/17) 80.5-100%
Investigational Site 3 assessed sensitivity with sera from dengue patients who
were culture positive (dengue type specific) or were hemagglutination
inhibition (HI) positive
Focus IgG ELISA Sensitivity with Culture or HI Positives (Site 3)
Condition Sensitivity 95% CI
Type 1 Culture Positive 88% (7/8) 47.3-99.7%
Type 2 Culture Positive 100% (1/1) NA
Type 3 Culture Positive 100% (5/5) 47.8-100%
Type 4 Culture Positive 100% (1/1) NA
HI Positive 96% (23/24) 78.9-99.9%
Overall 95% (37/39) 82.7-99.4%
* Positive results are expected with an asymptomatic population since IgG has
been detected in patients as long as sixty years post-infection. Asymptomatic
persons are included in the sensitivity section instead of the specificity section
because the device’s use is to “establish previous exposure” and not to aid in
the diagnosis.
Investigational Site 5 assessed sensitivity with paired sera from dengue
patients (total patients = 30, total samples = 61). Sera were selected as
follows:
1. Each patient was suspected as being infected with dengue virus,
2. the pairs showed either seroconversion by IHA or at least a two fold
increase in antibody titer for the paired samples by IHA, and
3. at least one of the paired samples was IgM positive by the investigator's
ELISA.
Sensitivity with Paired Sera (Site 5)
Device First Draw Second Draw Third Draw
Sensitivity 95% CI Sensitivity 95% CI Sensitivity 95% CI
Investigator's 13%
100%
100%
3.8-30.7%
88.4-100%
HI (4/30)
(30/30)
(1/1)
NA
Investigator's 20%
100%
100%
7.7-38.6%
88.4-100%
IgM ELISA (6/30)
(30/30)
(1/1)
NA
Focus IgG
ELISA
30%
(9/30)
14.7-49.4%
90%
(27/30)
73.5-97.9%
0%
(0/1)
SPECIFICITY
Investigational Sites 4 and 5 assessed specificity by assaying sera from
asymptomatic persons from endemic and non-endemic areas.
Focus IgG ELISA Specificity with Normal Sera (Sites 4 & 5)
Condition Specificity 95% CI
Non-endemic Normal (Site 4) 99% (158/160) 95.6-99.9%
Endemic Children (Site 5) 100% (43/43) 91.8-100%
Endemic Adults (Site 5) 77% (52/68) 64.6-85.9%
Overall Endemic 86% (95/111) 77.7-91.5%
Overall Endemic &
Non-endemic
93% (253/271) 89.7-96.0%
CROSS-REACTIVITY
Investigational Site 2 assessed cross-reactivity by testing patients vaccinated
with Yellow Fever Virus and from patients with influenza infections.
Focus IgG ELISA Specificity with Potentially Cross-reactive Sera (Site 2)
Condition Specificity 95% CI
Yellow Fever Virus 50% (3/6)* 11.8-88.2%
Vaccinations*
Influenza Infections** 60% (9/15)** 32.3-83.7%
Overall Specificity 57% (12/21) 34.0-78.2%
* Site 2 also found that 33% (2/6) yellow fever virus vaccination sera had very
high titers (over 1/10,000) with the investigator’s ELISA.
** Site 2 also found that 31% (5/16) influenza infection sera had high titers
(over 1/600) with the investigator’s ELISA
NA

FOCUS Diagnostics
Investigational Site 8 assessed cross-reactivity by testing sera from patients
infected with other flaviviruses, and sera from patients infected with other
viruses. Both serum panels were assayed using the Focus device, the
investigator's HI, and the investigator's IgM ELISA. The flavivirus serum
panel consisted of 33 sera from patients infected with other flaviviruses:
Yellow Fever virus, West Nile virus, Chinkunyungunya virus, Japanese
encephalitis virus, Sandfly fever virus, Langat virus, Bunya virus, and
Wassalbron virus.
Cross-reactivity with Flavivirus Infections (Site 8)
Device Cross-reactivity 95% CI
Investigator's Dengue 39% (13/33) 22.9-57.9%
Type 2 HI
Investigator's Dengue 12% (4/32) 3.5-29.0%
ELISA IgM
Focus Dengue IgG
ELISA
61% (20/33) 42.1-77.1%
Focus IgG ELISA Cross-reactivity
with Non-flavivirus Viral Infections (Site 8)
Device
Cross-reactivity
EBV VCA CMV HSV VZV Parvovirus Overall
Investigator's
HI
0%
(0/4)
0%
(0/4)
0%
(0/5)
33%
(1/3)
20%
(1/5)
10%
(2/21)
Focus IgG
ELISA
25%
(1/4)
0%
(0/4)
0%
(0/5)
33%
(1/3)
40%
(2/5)
19%
(4/21)
STABILITY
Released components were accelerated to at least an equivalent of 1 year at 2
to 8°C by incubating at 37°C. The accelerated components were then tested
according to the package insert in parallel with unaccelerated components.
Components are considered stable if they meet the QC criteria specified in the
package insert. The device passed each of the QC criteria.
INTRA-ASSAY REPRODUCIBILITY
Investigational Site 4 assessed intra-assay variation. Two strips each (8 wells
per strip) were removed from six different plates, and the removed strips were
re-assembled into a new plate (12 strips total, 96 wells total). The new plate
was used to run an assay according to the package insert using Cut-off
Calibrator as a sample. The device demonstrated the following intra-assay
variation:
Dengue Virus IgG DxSelect
Page 2
INTER-ASSAY REPRODUCIBILITY
Investigational Site 4 assessed inter-assay variation. The controls and two
different samples (one borderline and positive sera) were run once a week for
six weeks. Each assay was run as described in the package insert. Mean,
standard deviation (S.D.), coefficient of variation (C.V.), and % agreement for
interpretation were calculated.
Focus IgG ELISA Inter-assay Reproducibility
Item n Mean S.D. C.V. % Agreement
Cut-off Calibrator O.D. 6 0.342 0.055 16.1% NA
Non-Detectable Control Index 6 0.023 0.011 49.4% 100% (6/6)
Detectable Control Index 6 2.125 0.105 5.0% 100% (6/6)
High Positive Control Index 6 4.990 0.396 7.9% 100% (6/6)
(no longer available)
Borderline Serum Index 6 0.965 0.148 15.4% 67% (4/6)
Positive Serum Index 6 4.818 0.515 10.7% 100% (6/6)
INTER-LOT REPRODUCIBILITY
Investigational Site 7 assessed inter-lot variation. The controls and different
samples (five positive and three negative sera) were run with two separate kit
lots . The device demonstrated the following reproducibility.
Sample #
Index
Interpretation
Lot 1 Lot 2 % Agreement
QC 1 0.412 0.166 100%
QC 3 0.899 0.482 100%
QC 4 1.294 1.596 100%
QC 6 2.540 2.750 100%
QC 7 3.726 4.174 100%
QC 8 7.136 6.449 100%
QC 9 13.521 10.504 100%
QC 10 0.062 0.114 100%
PC.EL1500G
Rev.F
Date written 11 Aug 2008
Focus IgG ELISA Intra-assay Reproducibility
Wells Mean O.D. Coefficient of
Variation
Strips
Plate
1 & 2 1 0.143 3.2%
3 & 4 2 0.142 5.0%
5 & 6 3 0.139 4.6%
7 & 8 4 0.134 5.9%
9 &10 5 0.136 4.8%
11 & 12 6 0.143 5.8%
All twelve strips, two strips
from each plate (n = 96 wells)
0.139 5.4%
Cypress, California 90630 USA
www.focusdx.com