Helicobactor pylori: Likelihood Ratios

Introduction: From UpToDate (http://www.utdol.com/online/content/topic.do?topicKey=acidpep/4732 ):

The ACG guidelines made the following conclusions:

Testing for H. pylori should be performed only if the clinician plans to offer treatment for positive results.

* Testing is indicated in patients with active peptic ulcer disease, a past history of documented peptic ulcer or gastric MALT lymphoma.

The test-and-treat strategy for H. pylori (ie, test and treat if positive) is a proven management strategy for patients with uninvestigated dyspepsia who are under the age of 55 years and have no "alarm features" (bleeding, anemia, early satiety, unexplained weight loss, progressive dysphagia, odynophagia, recurrent vomiting, family history of GI cancer, previous esophagogastric malignancy).

* Deciding which test to use in which situation relies heavily upon whether a patient requires evaluation with upper endoscopy and an understanding of the strengths, weaknesses, and costs of the individual test.

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The likelihood ratios of findings for Helicobactor pylori are listed below. See the left navigation bar to change the display.

Pre-Test Probability (Prevalence): %.	Post-Test Probability (Predictive Value): %.	Switch to display mode.
Note that calculating probabilities from more than one** finding is inherently inaccurate because findings are not independent. (For example, using two positive findings that share a common pathogenesis is likely to overestimate the true probability.)

Good Positive Likelihood Ratio
Finding	Result	+LR	-LR
[ + ] Biopsy culture	+ 0 -	22.5	0.6
In addition to diagnosis, biopsy culture allows for determination of antibiotic sensitivity Study: Am J Gastroenterol. 2006 Apr;101(4):848-63. PMID 16494583

Good Positive and Negative Likelihood Ratios
Finding	Result	+LR	-LR
[ + ] Antral biopsy urease test	+ 0 -	18	0.1
[sens/spec is per UpToDate] One reason for lack of specificity: If specifmen contains less common non-pylori gastric helicobacters, which give only weakly positive results in the biopsy urease test. Positive identification of these bacteria requires visualization of the characteristic long, tight spirals in histologic sections. Adapted from Harrison's Online Chapter 144: Helicobactor pylori infections Study: Am J Gastroenterol. 2007 Aug;102(8):1808-25. PMID 17608775
[ + ] Urea breath test	+ 0 -	11.6	0.1
in patients with an UGIB. Study: Am J Gastroenterol. 2006 Apr;101(4):848-63. PMID 16494583
[ + ] Stool antigen test	+ 0 -	2.9	0.2
in patients with UGIB Study: Am J Gastroenterol. 2006 Apr;101(4):848-63. PMID 16494583
[ + ] Serology	+ 0 -	2.8	0.2
in patients with UGIB Study: Am J Gastroenterol. 2006 Apr;101(4):848-63. PMID 16494583
[ + ] Biopsy histology	+ 0 -	7	0.3
in patients with UGIB. Study: Am J Gastroenterol. 2006 Apr;101(4):848-63. PMID 16494583
[ + ] Rapid urease test	+ 0 -	9.6	0.4
in patients with UGIB. Study: Am J Gastroenterol. 2006 Apr;101(4):848-63. PMID 16494583