What is the sensitivity and specificity of serology (blood test for antibodies) testing for H. pylori (Helicobacter pylori) infection?

Sensitivity and Specificity of Serology Testing for H. pylori Infection

Standard serological tests for H. pylori have moderate sensitivity of approximately 85% and limited specificity of about 79%, making them inadequate for routine clinical diagnosis of active infection. 1

Serological Test Performance

Standard ELISA Serology Tests

• Sensitivity: 85% (based on meta-analysis of 21 studies) 1
• Specificity: 79% (based on meta-analysis of 21 studies) 1
• Overall accuracy: 78% (range 68-82%) across 16 different tests evaluated by the Medical Devices Agency of Great Britain 1

Key Limitations of Serological Testing

• Cannot distinguish between active infection and previous exposure 1
• Antibody levels persist in blood for long periods after successful treatment 2
• Leads to false-positive results in previously treated patients 1

Specialized Serological Tests

• Anti-CagA ELISA tests show variable performance:
  • HeloriCTX: Sensitivity 100%, Specificity 76% 1
  • Radim 2: Sensitivity 90%, Specificity 94% 1
• Western blotting tests (Helico-blot 2.0, RIBA) show improved sensitivity and specificity but are primarily used for research purposes 1

Near-Patient (Rapid) Tests

• Mean sensitivity: 71.1% (weighted for patient numbers) 1
• Mean specificity: 87.6% (weighted for patient numbers) 1
• These rapid office-based tests perform considerably worse than laboratory-based tests 1

Alternative Testing Methods

Urea Breath Test (UBT)

• Sensitivity: 97% 1
• Specificity: 95% 1
• Considered superior to serology for active infection detection 2

Stool Antigen Test (SAT)

• High sensitivity and specificity comparable to UBT 2
• Can directly detect presence of H. pylori bacteria 2
• Recommended by European Society of Clinical Microbiology and Infectious Diseases 2

Clinical Considerations

When Serology May Be Appropriate

• In specific clinical scenarios where other tests might yield false negatives:
  • Recent use of antimicrobial drugs 1
  • Recent use of antisecretory drugs (PPIs) 1
  • Ulcer bleeding 1
  • Gastric atrophy 1
  • Gastric malignancies 1
• Large epidemiological surveys 1
• Studies on age at acquisition of infection 1

Important Caveats

• Only validated IgG serology tests should be used due to variability in commercial test accuracy 1
• PPIs should be stopped for 2 weeks before testing with non-serological methods 1
• Some recent research suggests serology may have higher sensitivity (94%) than previously reported when compared to histopathology 3
• Multiplex serology targeting specific proteins (VacA, GroEl, HcpC, HP1564) may better discriminate active from past infection 4

Recommended Testing Approach

• For initial diagnosis: Urea breath test or stool antigen test are preferred over serology due to higher specificity for active infection 2
• For post-treatment evaluation: Never use serology as antibodies persist after successful eradication 2
• If patient is on PPIs and cannot stop for 2 weeks: Use validated IgG serology 1

The stool antigen test or urea breath test should be used for diagnosing active H. pylori infection due to their superior ability to distinguish current from past infection compared to standard serology. 2