Re: New here questions on lyme and other

On Feb 21, 8:34 pm, the 3rd Man <sir_de...@xxxxxxxxx> wrote:
On Feb 21, 6:38 pm, cowabungabartnewsgrouplea...@xxxxxxxxx wrote:



If the test is no better than  flipping a coin it doesn't matter
whether the blood is from the same person or not. NO the coin flip
analogy works it is based on the test not the test subject-

Huh?

Well, first of all, it just isn't a 50-50 coin flip.

But, in theory, I suppose an individual may have characteristics
different enough from the population that the tests were validated
upon to possibly make a difference...I suppose.

In other words, what's your universe?

In statistical theory, though, if the test population were properly
drawn...this probably wouldn't be the case.

Once again YES I ABSOLUTELY DO UNDERSTAND WHAT YOU ARE SAYING! I
promise you, I do.

I swear the problem is that you aren't understanding what I'm saying.

The two analyses measure different phenomenon.

One (yours) measures the chances of a random event happening in an
apparently non random fashion serially.

Fine. No problem. The chances of a random event happening in an
apparently non random fashion serially are small. However, that
doesn't bring you to a fair or accurate conclusion that it IS a non
random event. The fact that it can be predicted to occur by
probability theory means that no matter how small the probability it
does happen.

This happens alot when playing texas hold em.

One player has a hand based on their hole cards and their odds of
winning might be 90-10. The person with the 90% odds doesn't realize
that when they get beat it isn't such an unusual thing--it happens one
in ten times. Is that a "bad beat"? Sure if you want to look at it
that way. Bad luck? Sure if you want to look at it that way. But one
in ten isn't so unusual, it happens one in ten times!

The other phenomenon being measured is that the chances of a random
event occurring contrary to its odds over enough trials is basically
zero. In other words if the event is a 50 50 it doesn't always happen
heads tails heads tails heads tails. The 50 50 proves out over the
course of enough trials inevitably. The fact that during the course of
those trials it might be heads heads heads heads heads heads heads is
small but it does happen. That doesn't change the fact that it is a 50
50 proposition.

Since it is a 50 50 proposition (accept that for the sake of argument)
the fact that this random event does occur in an APPARENTLY non random
fashion serially does NOT mean it IS a non random event in fact it IS
predictable that x number of times in y number of trials that will
occur z number of times.

Now, lets look at a paper on the CDC site which shows that 2 out of 5
investigators using ELISA had a 50% or LESS sensitivity (others were
higher but all tended to be in the mid 70%).

Showing that in the REAL UNIVERSE and that is the one I'm talking
about these tests suck!

http://www.cdc.gov/ncidod/eid/vol2no2/craven.htm


Emerging Infectious Diseases * Volume 2 * Number 2 April-
June 1996

--------------------------------------------------------------------------------
Dispatches
Improved Serodiagnostic Testing for Lyme Disease: Results of a
Multicenter Serologic Evaluation

--------------------------------------------------------------------------------
Download Article
The diverse clinical manifestations of Lyme disease (1-3) have led to
frequent confusion in clinical diagnosis, a confusion compounded by
problems in the accuracy and precision of diagnostic serologic tests
(4-11) and the difficulty of isolating the causative organism (12-14),
Borrelia burgdorferi. In 1990, more than 20 commercially prepared
serologic test kits for Lyme disease were being sold in the United
States, but no nationally standardized reference test was available. A
collaborative evaluation of a selected sample of the commercial test
kits by the Centers for Disease Control and Prevention (CDC) and the
Association of State and Territorial Public Health Laboratory
Directors (ASTPHLD) demonstrated poor concordance of results among
these test kits and among a selected group of state health department
laboratories (11). Because of the lack of a rigorously defined
reference serum panel, conclusions could not be drawn about the
sensitivity and specificity of the test kits evaluated. An unexpected
finding in this study was the low concordance in test results between
CDC and two consulting academic reference center laboratories. A
number of other studies also have demonstrated low concordance of Lyme
disease serologic test results obtained by a variety of laboratories
(4-10).

As a result of those findings, the study described here was designed
to fulfill the following objectives: 1) to assemble a serum panel from
patients who had clinically well-defined Lyme disease (preferably
confirmed by isolation of B. burgdorferi); healthy controls, and
persons residing in non–endemic-disease areas whose potentially cross-
reactive specimens had yielded equivocal ELISA results in earlier CDC
tests; 2) to test this panel in a blinded fashion by several
recognized Lyme disease reference and research laboratories; and 3) to
compare the accuracy and precision of tests as a prelude to developing
national recommendations for standardized serologic testing for
antibodies to B. burgdorferi.

Tests were performed by five academic centers active in Lyme disease
research (the Marshfield Clinic, Marshfield, Wisconsin; University of
Medicine and Dentistry of New Jersey–Robert Wood Johnson Medical
School, New Brunswick, New Jersey; State University of New York at
Stony Brook, Stony Brook, New York; Tufts/New England Medical Center,
Boston, Massachusetts; and the University of Connecticut Health
Center, Farmington, Connecticut) and CDC’s Division of Vector-Borne
Infectious Diseases, National Center for Infectious Diseases, based in
Ft. Collins, Colorado.

Serum samples from Lyme disease case-patients were obtained from the
participating academic investigators (n = 72) and from the CDC Lyme
disease reference serum collection (n = 37). All case-patient serum
samples (total = 109) were from patients who met the CDC clinical case
definition for surveillance of Lyme disease (15). The clinical
manifestations in these patients ranged from acute erythema migrans
(EM) to late neurologic disease accompanied by Lyme arthritis. B.
burgdorferi had been cultured by the method of Berger et al. from 14
of 34 (41%) acute-phase specimens provided by CDC (14). Duplicate
specimens (n = 85) were randomly selected from the 109 case-patient
samples for precision analysis, making a total of 194 case-patient
samples in the panel.

Control serum samples were provided by CDC from unpaid healthy blood
donors (n = 113) who resided in areas where Lyme disease is not
endemic (Cincinnati, Ohio, and Atlanta, Georgia; travel histories were
not available from these donors, however. Duplicate specimens (n = 87)
also were randomly selected, resulting in 200 noncase samples in the
serum panel. Additional control samples were obtained from persons who
resided in areas where Lyme disease was not endemic but whose
physicians submitted their serum for Lyme disease testing to CDC
through their state health department (n = 113). These specimens from
patients with suspected cases had borderline (equivocal)
seroreactivity in the whole cell sonicate (WCS) enzyme-linked
immunoassay (ELISA)used by CDC before 1992 and are referred to
hereafter as “WCS-suspects” (16). The addition of duplicate specimens
(n = 87) brought this group to 200 equivocally seroreactive samples.

Serum was separated and frozen by the original collectors and shipped
frozen to CDC’s facilities in Ft. Collins, Colorado. The specimens
were divided into aliquots and coded; code labels were applied by CDC
staff not involved in serologic testing of the specimens (n = 594).
The panels were then refrozen and shipped on dry ice for blind testing
by participating investigators. All specimens were received frozen. To
calculate test sensitivity and specificity, only the result of the
sample with the lower random code number of each pair was used.

Each laboratory employed the testing method that it used routinely at
the time this study was undertaken (1992). CDC used an ELISA with a
WCS antigen prepared from highly passaged strain B31 (gift of A.
Barbour, University of Texas Health Sciences Center, San Antonio,
Texas) and an ELISA with a strain B31 flagellar antigen (FLA) then
being evaluated (16, 17). The other five participating investigators
used ELISA tests that employed a WCS antigen of B. burgdorferi. Four
used assays developed in their own laboratories, and one used a
commercially available test kit (18-22). Three investigators also
tested all specimens by Western blotting using published methods (19,
20). Two of these three performed immunoblotting for IgM and IgG
antibodies separately. One laboratory tested for IgM and IgG
together.

Each participating laboratory submitted the raw data of its results,
along with a dichotomous interpretation of those results as either
positive or negative. By prior agreement, ELISA results that fell into
a range ordinarily reported as “equivocal” by that laboratory were
treated as negative for this analysis. Statistical analyses undertaken
at CDC included calculations of sensitivity (true positives correctly
identified), specificity (true negatives correctly identified),
precision (frequency of obtaining the same result on duplicate
analysis of a specimen), and a measure of concordance (agreement among
investigators) of results among the tests using the kappa statistic.

The accuracy and precision of the serologic tests as performed in 1992
by all six laboratories is summarized in Table 1. The test methods of
investigators 1, 2, and 3 produced essentially equivalent results,
with moderately high sensitivity (73% to 79%) for the aggregate of all
case-patient samples tested and high specificity (98% to 99.5%).
Precision was high in these three laboratories for both blood donor
samples (97% to 99%) and the WCS-suspects samples submitted from areas
where Lyme disease is nonendemic (94% to 98%). Precision was somewhat
lower for the case-patient samples (82% to 91%).

Table 1. Accuracy and precision of serologic tests for Lyme disease
performed in 1992 Accuracy (%) Precision(%)
Investigator Sensitivity Specificity Case
patients Non-case-
patients WCS
suspectsª
CDC
(WCS) 93 71 93 77 69
CDC
(FLA) 92 82 92 79 62
1 73 99.5 89 99 98
2 76 99 82 99 97
3 79 98 91 97 94
4 49 91 79 94 93
5 40 72 63 74 77
ª Specimens from patients with suspected cases that had borderline
(equivocal) seroreactivity in an enzyme-linked immunosorbent assay
with whole-cell sonicate antigen (WCS).


The performance of the other three laboratories, including CDC’s, was
poor. Both CDC ELISA tests had high sensitivity (92% to 93%), but low
specificity (71% to 82%). Precision for case-patient specimens was
fairly high (92% to 93%), but low for both non-case-patient (77% to
79%) and WCS-suspects groups (62% to 69%). The method of investigator
4 gave very low sensitivity (49%), moderately high specificity (91%),
poor precision with Lyme disease case-patient specimens (79%), but
good precision with blood donor and WCS-suspects samples (93% to 94%).
Investigator 5, who used a commercial test, obtained results with low
accuracy and precision.

Concordance was high (kappa statistic 0.700) between the results of
investigators 1, 2, and 3. The CDC FLA test showed moderate
concordance (kappa 0.400) with results from investigators 1, 2, and 3.
The results of investigator 4 showed moderate concordance with those
of investigators 1 and 2 (kappa 0.400) and low concordance (0.400)
with the other results. The results of investigator 5 had low
concordance with all other results. The CDC WCS test showed moderate
concordance with the FLA test, but low concordance with results of the
ELISA tests of the other laboratories.

The three investigators with the best results all used Western blot to
supplement their ELISA. Two of these three investigators submitted
their dichotomous test interpretation with and without using Western
blot results. The sensitivity improved by 20% for one investigator and
by 30% for the other when Western blot results were included. The
improvement resulted from identifying as positive by Western blot
those case-patient specimens from which an equivocal result was
obtained by ELISA and which by study design would have been counted as
negative by ELISA results alone. Specificities were not affected by
Western blot analysis in this group of three investigators, since the
serum panel in this study did not contain cross-reactive sera; and the
negative controls and WCS-suspects had negative results by both ELISA
and Western blot.

Test sensitivity from the three laboratories with the best test
specificity (98%) was analyzed according to the clinical
manifestations in the case-patients (Table 2). As expected, the
sensitivities of the tests were lowest in specimens from patients with
early disease, 59% to 66% for erythema migrans and 63% to 75% for
early neurologic disease. Sensitivities were much higher for samples
of patients with late disease. Sensitivities of 89% to 95% were
obtained for Lyme arthritis patients and 91% to 100% for persons with
late neurologic disease, primarily encephalopathy or polyneuropathy.

The emergence of a disease can outstrip the development of reliable
methods for its laboratory diagnosis. The serodiagnosis of Lyme
disease has been fraught with problems of precision and accuracy. This
study provided an opportunity for selected academic research centers
and CDC to compare the performance of their individual tests by using
a serum panel from clinically well-characterized patients and controls
from non–endemic-disease areas. The clinical diagnosis of early Lyme
disease was supported by the isolation of B. burgdorferi from skin
biopsy specimens (14), when possible. The panel, which was coded blind
had a sufficiently large number of samples (n = 335) to provide
adequate statistical power for the comparison.

Table 2. Test sensitivity of laboratories demonstrating a test
specificity of 98% Sensitivity, % (positive samples/total)
Clinical Manifestations Laboratory 1 Laboratory 2 Laboratory 3
Erythema migrans, all 59 (55/94) 60 (56/94) 66 (62/94)
Acute phasea 65 (11/17) 65 (11/17) 76 (13/17)
Convalescent phaseb 57 (44/77) 58 (45/77) 64 (49/77)
Carditis 100 (2/2) 100 (2/2) 100 (2/2)
Lyme arthritisc 89 (58/65) 95 (62/65) 92 (60/65)
Neurologic, all 85 (28/33) 88 (29/33) 91 (30/33)
Early 63 (5/8) 63 (5/8) 75 (6/8)
Late 91 (10/11) 100 (11/11) 91 (10/11)
Late and arthritis 93 (13/14) 93 (13/14) 100 (14/14)
Total 74 (143/194) 77 (149/194) 79 (154/194)
a <=30 days from onset of erythema migrans to blood collection.
b > 30 days from onset of erythema migrans to blood collection.
c Without neurologic signs or symptoms.


Laboratories that supplemented their primary test, an ELISA, with
immunoblotting achieved greater test accuracy than those that did not.
The use of Western blot as a second test enabled the best performing
laboratories to increase test sensitivity without a concomitant loss
of specificity. This increase in sensitivity occurred as a result of
identifying as true positives by Western blot a number of those
specimens from patients with clinical cases of Lyme disease that were
interpreted as equivocal by ELISA and would have been otherwise
considered in this study as dichotomously negative results. Although
the investigators employing Western blot tested all panel specimens
with this method, they did so at that time to evaluate the potential
value of Western blot in Lyme disease serologic diagnosis.

The observation that Western blotting could be employed to resolve
equivocal ELISA results gave additional impetus for evaluating its
potential adjunctive role in Lyme disease serodiagnosis and eventually
led to the finally recommended two-test approach (23). The potential
utility of Western blotting, however, pointed out the lack of
standardized methods for producing blots and standardized interpretive
criteria.

Performance of the CDC WCS and FLA ELISA in this study that did not
include known cross-reactive sera suggested that the positive cut-off
value for these tests was inappropriately low, thereby increasing
sensitivity at the expense of specificity. These results then
explained the large number of borderline WCS ELISA results obtained by
CDC when it tested the sera of patients residing in areas where Lyme
disease was not endemic. This group of WCS suspects was nearly
uniformly found to be negative on ELISA by the three laboratories with
the best performance (Table 1) (23).

Specificity in this study was determined by testing specimens from
blood bank donors. With these samples, specificity in the three
laboratories that used immunoblotting was very high (98% to 99.5%).
The test panel did not, however, contain specimens frompatients with
conditions known to produce cross-reacting antibodies (e.g., syphilis)
or polyclonal B-cell activation (e.g., Epstein-Barr virus infection or
systemic lupus erythematosus). Thus, reported specificities in this
study are likely higher than they would have been if cross-reactive
specimens were included in the evaluation. Subsequent studies that
included cross-reactive sera demonstrated that Western blotting
correctly identifies many false-positive ELISA reactions (23, 24).

This study confirmed in the reference and research laboratory setting
the previously documented problems with accuracy and precision of
serodiagnostic tests by using WCS antigens of B. burgdorferi (4-11).
The study confirmed that a serious disparity existed between the test
results obtained by CDC and those obtained by academic reference
centers with the best testing performances. These results guided
corrective action and led to the adoption by CDC and ASTPHLD of a two-
test approach to serodiagnosis (23), which forms the basis for the
future national standardization of Lyme disease serologic testing
methods.

Robert B. Craven,* Thomas J. Quan,* Raymond E. Bailey,* Raymond
Dattwyler,† Raymond W. Ryan,‡ Leonard H. Sigal,§ Allen C. Steere,¶
Bradley Sullivan,# Barbara J.B. Johnson,* David T. Dennis,* and Duane
J. Gubler*

*Centers for Disease Control and Prevention, Fort Collins, Colorado,
USA; †State University of New York at Stony Brook, Stony Brook, New
York, USA; ‡University of Connecticut Health Center, Farmington,
Connecticut, USA; §University of Medicine and Dentistry of New Jersey–
Robert Wood Johnson Medical School, New Brunswick, New Jersey, USA;
¶Tufts/New England Medical Center, Boston, Massachusetts, USA;
#Marshfield Clinic, Marshfield, Wisconsin, USA

A portion of this information was presented at the VIth International
Conference on Lyme Borreliosis, Bologna, Italy, June 1994 and at the
Second National Conference on Serologic Diagnosis of Lyme Disease,
Dearborn, Michigan, October 1994.

References

Steere, AC. Lyme disease. N Engl J Med 1989;321:586-96.
Logigian EL, Kaplan RF, Steere AC. Chronic neurologic manifestations
of Lyme disease. N Engl J Med 1990;323:1438-44.
Steere AC, Bartenhagen NH, Craft JE, et al. The early clinical
manifestations of Lyme disease. Ann Intern Med 1989;99:76-82.
Bakken LL, Case KL, Callister SM, Bourdeau NJ, Schell RF. Performance
of 45 laboratories participating in a proficiency testing program for
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Hedberg CW, Osterholm MT, MacDonald KL, White KE. An interlaboratory
study of antibody to Borrelia burgdorferi. J Infect Dis
1987;155:1325-7.
Hedberg CW, Osterholm MT. Serologic tests for antibody to Borrelia
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Jones JM. Serodiagnosis of Lyme disease. Ann Intern Med
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Lane RS, Lennette ET, Madigan JE. Interlaboratory and intralaboratory
comparisons of indirect immunofluorescence assays for serodiagnosis of
Lyme disease. J Clin Microbiol 1990;28:1774-9.
Luger SW, Krauss E. Serologic tests for Lyme disease: interlaboratory
variability. Arch Intern Med 1990;15:761-3.
Schwartz BS, Goldstein MD, Ribeiro JMC, Schulze TL, Shahied SI.
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laboratories. JAMA 1989;262:3431-4.
Quan TJ, Wilmoth BA, Carter LG, Bailey RE. A comparison of some
commercially available serodiagnostic kits for Lyme disease. In:
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of Lyme disease. N Engl J Med 1983;308:733-40.
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Dressler F, Whalen JA, Reinhardt BN, Steere AC. Western blotting in
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