Point-of-care Helicobacter pylori testing: primary care technology update

BACKGROUND AND ADVANTAGES OVER EXISTING TECHNOLOGY

Helicobacter pylori (HP) infection causes approximately 5% of uninvestigated dyspepsia and a 20% lifetime risk of peptic ulcer disease.¹ HP is a grade 1 carcinogen: 5.2% of cancers globally are attributable to HP infection.² HP eradication results in: reduced gastric cancer incidence; prevention of recurrent duodenal (number needed to treat [NNT] = 2) and stomach (NNT = 3) ulceration; and resolution of dyspepsia (NNT = 13).³

Non-invasive Helicobacter pylori diagnostic tests are available for point-of-care (POC) use in primary care and include IgG serology, ¹³C-urea breath test (UBT), and monoclonal stool antigen. Only UBT is sufficiently accurate to confirm current infection or eradication.⁴ HP IgG serology cannot differentiate current from past infection. Rapid qualitative stool antigen testing currently lacks diagnostic accuracy.

DETAILS OF TECHNOLOGY

Isotope ratio mass spectrometry (IRMS) is the most commonly used ¹³C-UBT method in the UK. However, the sampling procedure involves many opportunities for test incompletion: collection of the test from the pharmacy; returning for a subsequent extended appointment; sending the test to the laboratory; and awaiting results. In comparison, non-dispersive isotope selective infrared spectroscopy (NDIRS) has potential as a POC device: it can be used by non-specialist staff outside the laboratory setting, it is relatively inexpensive, and it gives results in 2–5 minutes.⁴

PATIENT GROUP AND USE

NDIRS may be appropriate for adults presenting to primary care with:¹

• uninvestigated dyspepsia and no alarm symptoms >4 weeks;

• past history of gastric or duodenal ulcer, taking or starting non-steroidal anti-inflammatory drugs (NSAIDS);

• unexplained iron-deficiency anaemia, idiopathic thrombocytopenic purpura (ITP), or B12 deficiency with normal colonoscopy and endoscopy; and

• need for confirmation of eradication following treatment.

PREVIOUS RESEARCH

COST-EFFECTIVENESS

No cost-effectiveness studies have been carried out on POC testing for HP infection in primary care. ¹³C-UBT testing in dyspeptic patients was found to be cost-effective in one study, with an incremental cost-effectiveness ratio (ICER) of £1000 per quality-adjusted life year compared with not testing at all.¹⁵ However, cost-effectiveness studies in other populations have not found ¹³C-UBT testing to be cost-effective, providing only small health benefits while significantly increasing costs compared with other tests.

RELEVANT GUIDELINES

International guidelines recommend: 1) a 2-week restriction of proton pump inhibitor (PPI) use, and 4 weeks of antibiotics and bismuth compounds, before HP testing; 2) a ¹³C-UBT ‘test-and-treat’ strategy in patients with uninvestigated dyspepsia without alarm symptoms; 3) testing in aspirin and NSAID users with a history of peptic ulcer; 4) testing and eradication in unexplained iron deficiency anaemia (IDA), ITP, and vitamin B12 deficiency; 5) ¹³C-UBT retesting >4 weeks after eradication therapy.¹

WHAT THIS TECHNOLOGY ADDS

The NDIRS ¹³C-UBT is more accurate than other non-invasive POC tests for the diagnosis of HP infection and confirmation of HP eradication. It has comparable accuracy with laboratory-based IRMS but has the potential to reduce delays in testing by enabling a rapid diagnosis, prior to treatment initiation. However, the health benefit of this reduction compared with non-POC tests is unclear.

The lack of robust evidence on the comparative accuracy of NDIRS in the primary care setting, and the impact of NDIRS testing on endoscopy demand, need urgent attention.

The available evidence suggests that, for patients with upper gastrointestinal symptoms, primary care-based NDIRS testing may reduce diagnostic delay and could reduce inappropriate prescription of eradication therapy by accurately confirming current infection.