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Helicobacter pylori: A Diagnostic Approach

Helicobacter pylori: A Diagnostic Approach. Raquel S. Watkins, M. D. Wake Forest University. Cases :. 1. 27 year old Hispanic man S: stomach pain ROS: (+) pain X 1 month, better w/ food Diet: spicy foods, caffeine, occasional etoh O: vital signs stable

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Helicobacter pylori: A Diagnostic Approach

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  1. Helicobacter pylori: A Diagnostic Approach Raquel S. Watkins, M. D. Wake Forest University

  2. Cases: 1. 27 year old Hispanic man • S: stomach pain ROS: (+) pain X 1 month, better w/ food Diet: spicy foods, caffeine, occasional etoh • O: vital signs stable Abd:: (+) epigastric tenderness, Heme (-) • A/P: Differential: dyspepsia: GERD, gastritis, PUD, pancreatitis stop etoh,caffeine, spices check amylase/lipase Zantac 150 mg.Qhs

  3. He returned within 4 weeks with the same complaints Compliant with Zantac H. pylori serology checked and (+) MOC therapy given Asymptomatic on follow up

  4. 2. 50 year old African-American woman with depression • S: new onset abd pain, burning sensation ROS: (+) early satiety, FH of GI tumor Diet: no change, no NSAIDs, no etoh Meds: St John’s Wort • O: Vital signs stable Abd: epigastric pain , Heme (-) • A/P: gastritis H. pylori serology checked and (+) MOC samples given without change in symptoms referred to endoscopy

  5. Clinical Questions: In an office based setting, when dealing with a dyspeptic patient: • What is the diagnostic performance of H. pylori tests? • How should the primary care physician approach making the diagnosis?

  6. Guidelines: • Maastricht Consensus Report: Management of Dyspepsia • AGA: Medical Consensus Statement: Management of Dyspepsia

  7. Factors in choosing a test: • History and physical • Precision • Accuracy • Cost

  8. Endoscopy culture biopsy histology and stain Clo test Non-invasive serology anti H. pylori IgG/IgA Lab ELISA or office kit quantitative or qualitative Urea breath test 13-C 14-C salivary testing urine testing Diagnosis of H. pylori Infection

  9. Comment on Office Kits: • Graham et al - prospective study of 551 serum samples from asymptomatic volunteers to compare Flexsure office kit to another office kit QuickVue, and ELISA against a positive C-UBT • Flexsure office kit was comparable to the ELISA (96% sensitivity and 95% specificity)

  10. Comment on Salivary IgG testing: • Fallone et al -prospective comparison (on 106 patients referred to a tertiary care for endoscopy) of Helisal salivary kit to serology and histology • Salivary IgG titers have low sensitivity and specificity (70’s) when compared to histology • Salivary IgG titers correlated significantly with serology • used as a research tool currently

  11. Diagnostic performance of H. pylori tests: A comparison • no comparison of all available tests • largest and best available evidence from Cutler et al. • blinded comparison of 6 independent tests (7 sets of readings) for detecting H. pylori. • compared the sensitivity, specificity, and negative and positive predictive value of the most widely available tests for the diagnosis of H. pylori • 268 patients identified who presented for endoscopy to large GI clinic in Michigan

  12. Endoscopy 3 biopsies Clo histology for acute and chronic inflammation Warthin-Starry silver stain single pathologist was blinded 3 non invasive tests 13 C-UBT Serology for IgG Serology for IgA performed blindly 6 Tests (7 readings):

  13. Gold Standard • No true diagnostic standard (culture) • Used concordance of >4 of 7 tests (+) to represent H. pylori infection • 173/268 patients (65%) had > 4 (+) parameters

  14. Prevalence 10% Population =1000 H. pylori + + - + 90 0 PPV = 100% Clo - 10 900 NPV=98.9% 100 900 Prevalence 90% Population=1000 H. pylori + + - + 806 0 PPV=100% Clo - 94 100 NPV=51.4% 900 100 Clo test: Sensitivity 89.6%, Specificity 100%

  15. Prevalence 10% Population 1000 H. pylori + - + 91 76 PPV=54.4 IgG - 9 824 NPV=98.9 100 900 Prevalence 90% Population 1000 H. pylori + - + 822 8 PPV= 99% IgG - 78 92 NPV =54% 900 100 Serum IgG: Sensitivity 91.3, Specificity 91.6

  16. Likelihood Ratios: • helps us when comparing one test to another to determine which is the better one to rule in or out disease • indicate by how much a given diagnostic test will raise or lower the pretest probability of target disorder • LR(+) =probability of a positive test if disease is present probability of a positive test if disease is absent = sensitivity 100% -specificity

  17. LR(-)=probability of a negative test if the disease is present probability of a negative test if the disease is absent = 100%- sensitivity specificity

  18. Case Controlled Seroepidemiologic study of H. pylori Prevalence: Malaty et al

  19. Revisiting Cases:27 year old Hispanic manwith dyspepsia. • Pretest probability =38% • <45 yo, no alarm sx = noninvasive • LR (+) of IgG Elisa/office kit = 10.9 • (+) test = post-test probability of 85% • LR(-) of IgG serology =0.09 • (-) test = post-test probability of 3% -4%

  20. 50 year old African-Americanwoman with dyspepsia • Never been treated • ? To endoscopy given alarm symptom • if noninvasive strategy: • pretest probability of 90% • using serology IgG • LR(+) = 10.9 • (+) test = post- test prob of > 99% • LR(-) = 0.09 • (-) test = post-test of 45% • ???empiric therapy

  21. User’s Guides to the Medical Literature (10,11) • Are the results valid? • What are the results? • Will the results help me in my patient care?

  22. Independent blinded comparison w/ reference standard? Was single experienced pathologist blinded? No gold standard, but reasonable to use concordance Does patient sample include an appropriate spectrum? Yes if your patent has nevr be treated before. Yes, trends in race, age, and Gi conditions consistent with literature No, was there a referral bias? Does Cutler’s article represent a believable estimate of the value of each test?

  23. Did the results of test being evaluated influence the reference standard? No Were the methods described clear enough to permit replication? Yes

  24. Is data necessary for calculation of likelihood ratios provided? Yes Will the tests be reproducible and well interpreted in my practice? Yes, but experienced pathologist needed local validation of serology kits and office kits needed

  25. Are the results applicable to my patients? Yes, if practice in a large urban population Yes, if patients meet exclusion criteria for no previous therapy for H. pylori Will the results change my management? Yes, given large likelihood ratios (>10), positive results will move probability of disease across a threshold.

  26. Will my patients be better off because of the test? • Yes • tests offer information beneficial to patient care • target disorder if left undiagnosed may be harmful • tests have acceptable risks • effective therapy for eradication exists

  27. Wake Forest University: Cost

  28. Cost:US NorthWest and National Reference Labs

  29. The End What is the diagnostic performance of H. pylori tests? • Clo, silver stain, serology, UBT all have large LR • Office kits available and accuracy comparable to lab serology • Best available data not perfect How should primary care physicians approach making diagnosis? • Use pretest probability and LR • Remember AA and Hispanics have high prevalence • consider recommended guidelines, accuracy, precision, cost • Patient outcome is uncertain in certain conditions

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