Product Manual

Limitations
• A negative test result does not exclude infection with influenza A or B.
Therefore, the results obtained with the Status Flu A & B should be used in
conjunction with clinical findings to make an accurate diagnosis. Additional
testing is required to differentiate any specific influenza A and B subtypes or
strains, in consultation with state or local public health departments.
• This test detects both viable (live) and non-viable influenza A and B. Test
performance depends on the amount of virus (antigen) in the specimen and may
or may not correlate with cell culture results performed on the same specimen.
• Status Flu A & B uses highly target specific monoclonal antibodies. As in most
immunoassays, it may fail to detect, or detect with less sensitivity, influenza A viruses
that have undergone minor amino acid changes in the target epitope region.
• Performance of the Status Flu A & B has not been established for monitoring
antiviral treatment of influenza.
• Children tend to shed virus more abundantly and for longer periods of time
than adults. Therefore, testing specimens from adults will result in lower
sensitivity than testing specimens from children.
• Positive and negative predictive values are highly dependent on prevalence.
False negative test results are more likely during peak activity when
prevalence of disease is high. False positive test results are more likely during
periods of low influenza activity when prevalence is moderate to low.
• Individuals who received nasally administered influenza A vaccine may
produce positive test results for up to three days after vaccination.
• The performance of this assay has not been evaluated for use in patients
without signs and symptoms of respiratory infection.
• This test cannot rule out diseases caused by other bacterial or viral pathogens.
• The performance of this test has not been evaluated for sample types other
than those specified in the Intended Use.
• The performance of this test has not been evaluated for
immunocompromised individuals.
User Quality Control
Internal Quality Control:
Each Status Flu A & B test device has built-in controls. The Control line at the C
position can be considered as an internal positive procedural control; i.e., a proper
amount of sample was used, sample was properly added to the Extraction Well,
sample migrated properly, and the reagent system worked properly. A distinct
reddish-purple Control line should always appear if the test has been performed
correctly. If the Control line does not appear, the test result is invalid and a new test
should be performed. If the problem persists, contact LifeSign at 800-526-2125 or
732-246-3366 for technical assistance. A clear background in the Test Result
Window is considered an internal negative procedural control. If the test is
performed correctly and the Status Flu A & B test device is working properly, the
background in the Test Result Window will be clear, providing a distinct result.
External Quality Control:
Good laboratory practice includes the use of external controls to ensure proper
kit performance. It is recommended that external control testing be performed
with each new operator and before using a new lot or shipment of Status Flu A
& B kits to confirm the expected Q.C. results, using the external controls
provided in the kit. The frequency of additional Q.C. tests should be determined
according to your laboratory’s standard Q.C. procedures and local, State and
Federal regulations or accreditation requirements. Upon confirmation of the
expected results, the kit is ready for use with patient specimens. If external
controls do not perform as expected, do not use the test results. Repeat the
tests or contact LifeSign Technical Assistance. The built-in reddish purple
Control line indicates only the integrity of the test device and proper fluid flow.
The Status Flu A & B kit contains two control swabs. Test the control swabs in
the same manner as patient specimens. When the positive control is tested,
reddish purple lines appear at the C, A and B positions. When the negative
control is tested, a reddish purple line appears at the C position only.
If the controls do not perform as expected, do not report patient results.
The use of positive and negative controls from other commercial kits has not
been established with Status Flu A & B test.
Expected Values
The prevalence of influenza varies every year and the rate of positives in
influenza testing varies depending on many factors, including the
specimen collection method, the test method used, the disease
prevalence, and the geographic location. The prevalence observed with
reference tests (culture and PCR) during the 2007-2009 clinical study for
Status Flu A & B was 27% for influenza A and 11% for influenza B.
Performance Characteristics
Clinical Performance
A prospective clinical study was conducted from January 2007 to March
2008 and during March and April 2009 to determine the performance of
Status Flu A & B for aspirate, nasopharyngeal swab, and nasal swab
specimens.
The samples were collected at 5 sites in the USA from patients who
visited physicians’ offices and clinics with signs and symptoms of
respiratory infection during the study period. All collected samples
were tested with Status Flu A & B, and were cultured. The culture was
used as the reference method. The total number of patients tested was
862, of which 30% were 5 and younger, 38% were 6-21 years old, and
the rest were older than 21. Forty eight (48) percent were male and
52% were female. In addition to the prospective clinical study, eighty
(80) positive influenza A or B frozen archived samples were tested with
Status Flu A & B.
The combined data from all sites of the prospective study are
presented in the tables below.
The samples that produced discrepant results between Status Flu A & B
and viral culture were further analyzed with proFLU plus by Prodesse
(real time RT-PCR, PCR hereafter). These results are presented in the
footnote below each table.
Flu A
Positive
Status
Flu A & B
Flu A
Positive
Flu A
Negative
Total Performance
Flu A
Negative
Total
41 30* 71
Sensitivity
95.3%
95% CI: 92.1-
98.5%
Specificity
85.7%
95% CI: 83.3-
88.1%
2** 180 182
43 210 253
Reference (Virus Culture) Results
Flu B
Positive
Status
Flu A & B
Flu B
Positive
Flu B
Negative
Total Performance
Flu B
Negative
Total
11 6* 17
Sensitivity
91.6%
95% CI: 83.6-
99.6%
Specificity
97.5%
95% CI: 96.5-
98.5%
1** 235 236
12 241 253
Reference (Virus Culture) Results
*Of 30 discrepant samples, 22 were positive by both Status Flu and PCR
**Of 2 discrepant samples, 1 was negative by both Status Flu and PCR
*Of 6 discrepant samples, all 6 were positive by both Status Flu and PCR
**The discrepant sample was positive by PCR
5
4
Interpretation of Results
Positive: A reddish purple Control line (C position) and a reddish purple
Test line (A or B position) indicate that Influenza A or B antigen has been
detected. Lines at the A and C positions indicate the presence of Influenza
type A viral antigen, and lines at the B and C positions indicate the
presence of Influenza type B viral antigen in the specimen. A positive result
does not rule out co-infections with other pathogens or identify any
specific influenza A virus subtype. Determination of a positive result can be
made as soon as both a visible Test line (either A or B) and Control line
appear.
Note: The Test line (reddish purple line) may vary in shade and intensity
(light or dark, weak or strong) depending on the concentration of antigen
detected. The intensity of the Control line should not be compared to that
of the Test line for the interpretation of the test result. Even a light or faint
Test line must be interpreted as a positive result.
Negative: Only a reddish purple Control line (C position), with no Test line
at the A or B position, indicates that Influenza A or B antigen has not been
detected. A negative result does not exclude influenza viral infection.
Determination of negative results should not be made before 15 min.
Invalid: A reddish purple line should always appear at the Control line
position (C). If a line does not form at the Control line position in 15
minutes, the test result is invalid and the test should be repeated with a
new Status Flu A & B test device.
NOTE: Co-infection with Influenza A and B is rare. Status Flu A & B
"dual positive" clinical specimens (Influenza A and Influenza B
positive) should be re-tested. Repeatable influenza A and B "dual
positive" results should be confirmed by cell culture or PCR testing
before reporting results.
INTERPRETATION OF RESULTS
Influenza
Date
ID
C
B
A
C
B
A
C
B
A
C
B
A
Any visible A and/or B Line(s)
with C Line is POSITIVE.
C
B
A
C Line only
NEGATIVE
C
B
A
C
B
A
C
B
A
No C Line
INVALID
Repeat with new
sample and device.
A line:
Influenza
type A
B line:
Influenza
type B
A & B lines:
Influenza
type A & B
Nasopharyngeal Swab Sample
Nasal Swab Samples
Flu A
Positive
Status
Flu A & B
Flu A
Positive
Flu A
Negative
Total Performance
Flu A
Negative
Total
26 51* 77
Sensitivity
89.6%
95% CI: 84.0-
95.2%
Specificity
77.0%
95% CI: 74.2-
79.8%
3** 171 174
29 222 251
Reference (Virus Culture) Results
*Of 51 discrepant results, 42 were positive by both Status Flu and PCR
**Of 3 discrepant results, 1 was negative by both Status Flu and PCR
Flu B
Positive
Status
Flu A & B
Flu B
Positive
Flu B
Negative
Total Performance
Flu B
Negative
Total
33 15* 48
Sensitivity
86.8%
95% CI: 81.4-
92.2%
Specificity
92.9%
95% CI: 91.2-
94.6%
5** 198 203
38 213 251
Reference (Virus Culture) Results
*Of the 15 discrepant results, 8 were positive by both Status Flu and PCR
**Of the 5 discrepant results, 2 were negative by both Status Flu and PCR
Flu A
Positive
Status
Flu A & B
Flu A
Positive
Flu A
Negative
Total Performance
Flu A
Negative
Total
33 80* 113
Sensitivity
91.7%
95% CI: 78.2-
97.1%
Specificity
75.2%
95% CI: 70.2-
79.6%
3** 242 245
36 322 358
Reference (Virus Culture) Results
*Of 80 discrepant results, 65 were positive by both Status Flu and PCR
**Of 3 discrepant results, all 3 were positive by PCR
Flu B
Positive
Status
Flu A & B
Flu B
Positive
Flu B
Negative
Total Performance
Flu B
Negative
Total
14 40* 54
Sensitivity
82.4%
95% CI: 59.0-
93.8%
Specificity
88.3%
95% CI: 84.4-
91.3%
3** 301 304
17 341 358
Reference (Virus Culture) Results
*Of 40 discrepant results, 19 were positive by both Status Flu and PCR
**Of 3 discrepant results, 1 was negative by both Status Flu and PCR
Nasopharyngeal Aspirate Sample