1 (US Patent No. US D560281 (S1); US D5601344 (S1); US ...

EXPECTED VALUES
The positivity rate for each laboratory will be dependent on several factors including the method of specimen collection, the
handling and transportation of the specimen, the time of year, and the prevalence of influenza A or B at the time of testing.
US influenza A rates (as reported by the US Centers for Disease Control) during the 2006-7 period of TRU FLU clinical trials
ranged from 4% in the months of October/November 2006 to a peak of 40% in February 2007. The influenza B positivity
rate peaked at approximately 8% during March/April 2007. The influenza A positivity rates at the clinical trial sites (based on
tissue culture) averaged 14% in the month of February and 10% in March. Influenza B rates varied from 11% to 18% during
the same time. The prevalence of Influenza A and B antigens in individuals showing signs and symptoms, as determined by
the TRU FLU Assay is summarized in Table 1.
Table 1: Prevalence of Influenza A and B antigens by patient age and sex as determined by TRU FLU
TRU FLU Influenza A Data distributed by TRU FLU Influenza B Data distributed by
gender and age of patient
gender and age of patient
Gender n TRU FLU A TRU FLU A Prevalence TRU FLU B TRU FLU B Prevalence
Positive Negative
Positive Negative
Female 319 69 250 21.6% 33 286 10.3%
Male 361 81 280 22.4% 25 336 6.9%
Unknown 5 0 5 0.0% 4 1 80.0%
Total 685 150 535 21.9% 62 623 9.1%
Age n TRU FLU A TRU FLU A Prevalence TRU FLU B TRU FLU B Prevalence
(years)
Positive Negative
Positive Negative
≤ 2 287 63 224 22.0% 17 270 5.9%
3 - 21 209 43 166 20.6% 36 173 17.2%
> 21 183 43 140 23.5% 5 178 2.7%
Unknown 6 1 5 16.7% 4 2 66.7%
Total 685 150 535 21.9% 62 623 9.1%
SPECIFIC PERFORMANCE CHARACTERISTICS
NOTE: Positive and negative predictive values are highly dependent on prevalence. False-negative 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.
Nine independent laboratories and the manufacturer, (located in distinct geographic regions), evaluated TRU FLU in parallel
with tissue culture. Six hundred and ninety seven fresh and 63 frozen samples, collected prospectively during the 2006-7
influenza season were tested. In the case of frozen samples, tissue culture tests were performed while they were fresh and
before they were frozen. Where possible, PCR testing was applied to samples to determine the true status (positive or
negative) of a sample when a discrepancy was observed between TRU FLU and tissue culture. Twenty seven percent
(185/697) of the prospective samples were from patients 22 years of age or older, 64% (447/697) from patients 12 years of
age or less and 8% (59/697) from patients 13 to 21 years of age. The age of six patients donating samples was not
recorded. Of the 63 samples tested only in the frozen state, the majority (33/63 or 52%) were from patients aged 2 months
to 2 years. The patient ages for the remaining retrospective samples were 14% (9/63) for patients aged 1 month or less,
22% (14/63) for patients aged 3-12 years, and 11% (7/63) for patients aged 13-21 years. Fifty three percent of the
prospective and 51% retrospective samples were from males while 47% prospective and 49% retrospective samples were
from females. The gender of five patients donating samples was not recorded. No differences in performance were
observed based on patient gender or patient age. The results of trials based on sample type and patient age are given in
Tables 2-4. Of the 697 prospective samples tested, 11 were not classified with respect to sample type and one produced
invalid culture results. These 12 samples were excluded from the calculations.
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