Comparison of stool immunoassay with standard methods for detecting Helicobacter pylori infection
BMJ 1999; 319 doi: https://doi.org/10.1136/bmj.319.7222.1409 (Published 27 November 1999) Cite this as: BMJ 1999;319:1409
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For me the thrust of these observations assist an evaluative process.
As the gut is an ongoing transitional enviroment yet another means is
discussed for commonsense affordable measurement. The complex ecology,
immune considerations, and other human factors related to gut well being
may not need perfect eradication strategies (or perfect tests) and perhaps
more the willingness work step by step toward restoration amidst all the
various imperfections of our living systems. Saying that does not limit
however my eagerness for the most accurate lab process possible.
Competing interests: No competing interests
The paper by Lehmann et al confirms the view that stool immunoassay
for Helicobacter pylori (HpSA) is a non-invasive, cheap and reliable test
for assessing Helicobacter pylori infection in unselected patients, but
seems to completely overlook the major issue concerning this diagnostic
tool, namely whether it is suitable for evaluating the outcome of
eradication therapy.
While some authors maintain that HpSA has a high specificity already
four weeks after the end of the eradicating treatment (1), others (2-4)
report a number of false-positive results after eradication.In particular,
when performed even two months after Helicobacter pylori eradication HpSA
still showed an unsatisfying specificity, with a 18% false positives (3).
The matter is generating much debate and although Vaira et al strongly
defend their own findings (5), they seek support in the results of recent
studies which, unfortunately, are yet unpublished and therefore
unavailable to the readers' evaluation.
Thus, for the time being, we must stick to the published information.
In this respect data presented at the recent International Workshop of the
European Helicobacter pilory Study Group held in Helsinki reconfirm that
in treated patients the specificity of HpSA is lower than that of C13 urea
breath test (6,7)suggesting that even six months after eradication the
amount of false positives is exceedingly high.
1.Vaira D, Malfertheiner P, Megraud F, Axon ATR, Deltenre M, Hirschi
AM et al. Diagnosis of Helicobacter pylori infection with a new non-
invasive antigen-based assay. Lancet 1999; 354: 30-33
2.Makristathis A, Pasching E, Schitze K, Wimmer M, Rotter ML, Hirschl
AM. Detection of Helicobacter pylori in stool specimens by PCR and antigen
enzyme immunoassay. J Clin Microbiol 1998; 36: 2772-2774
3.Trevisani L, Sartori S, Galvani F, Rossi MR, Ruina M, Chiamenti C,
Caselli M. Evaluation of a new enzyme immunoassay for detecting
Helicobacter pylori in feces: a prospective study. Am J Gastroenterol
1999; 94: 1830-1833
4. Plebani M, Basso D. Diagnosis of Helicobacter pylori infection by HpSA
test. Lancet 1999; 354: 1208
5. Vaira D, Malfentheiner P, Megraud P, Axon TRA. Diagnosis of
Helicobacter pylori infection by HpSA test. Lancet 1999; 354: 1732
6. Masoero G, Lombardo L, Della Monica P, Andrini L, Vicari S, Sallio
F, Pera A. Discrepancy between Helicobacter pylori stool antigen assay and
urea breath test in the detection of Helicobacter pylori infection. Gut
1999; 45 (suppl 111): A 131 (abstract)
7. Forne' M, Lite J, Dominguez J, Esteve M, Fernandez-Banares F et
al. Accuracy of a non-invasive immunoassay for detection of H.pylori
antigen in stools in the diagnosis of infection and follow-up after
eradication.
Gut 1999; 45 (suppl 111): A124 (abstract)
Competing interests: No competing interests
Stool antigen after therapy
We would like to comment the letter by Guslandi about the debate
concerning the specificity of the stool antigen test (HpSA) after
eradicating treatment, even if this is not pertinent to the paper by
Lehmann, reporting data on the test for detecting the infection only.
We think that only the evaluations published on peer reviewed journals
should be used for assessing the overall accuracy of a new test, because
abstracts of posters presented in congresses are not thoroughly verified
for their experimental design, statistical analysis and quality of data.
At this point few publications on peer reviewed journals are available. If
we include two of them which are accepted for publication, we would have
the following summary table, where the weighed mean for sensitivity and
specificity are 90.7% and 90.3%.
More studies will need to clarify the significance of the false
positive results, focusing on the possible presence of coccoid forms and
following these patients to verify their risk of reactivation in the
future compared to HpSA negative eradicated patients.
References
Makristathis A, Pasching E, Schutze K, et al. Detection of Helicobacter pylori in stool
specimens by PCR and Antigen
Enzyme Immunoassay. J Clin Microbiol 1998; 36: 2772-74.
Vaira D, Malfertheiner P, Megraud F et al. A noninvasive antigen assay for assessing
Helicobacter pylori eradication. A
European multicentre study. Gut 1999; 45: A105
Trevisani L, Sartori S, Galvani F, et al. Evaluation of a new enzyme immunoassay for
detecting Helicobacter pylori in faeces;
a prospective pilot study. Am J Gastroenterol 1999; 94: 1831-33.
Plebani M, Basso D. Diagnosis of Helicobacter pylori infection by HpSA test. Lancet 1999;
354: 209-1211)
Braden B, Teuber G, Dietrich CF et al. Stool test may defeat breath test: new faecal antigen
detects Helicobacter pylori
infection and eradication. BMJ, in press.
Competing interests: ____________________________________________________________Reference Patients Sens(%) Spec(%)____________________________________________________________Makristhatis, J Clin Microbiol 1998, Austria 55 85,7 68,3Vaira, AMJ in press, Europe 235 93,8 96,9Trevisani, AMJ 1999, Italy 116 93 82Plebani, Lancet 1999, Italy 45 73 93Braden, BMJ in press, 1999, Germany 115 91,3 94,6Weighted Mean 566 90,7 90,3____________________________________________________________