Eradicating H pylori

A second-order simulation model of the cost-effectiveness of managing dyspepsia in the United States

BACKGROUND

The "gold-standard'' evidence of effectiveness for a clinical practice guideline is the randomized controlled trial (RCT), although RCTs have a limited ability to explore potential management strategies for a chronic disease where these interact over time. Modeling can be used to fill this gap, and models have become increasingly complex, with both dynamic sampling and representation of second-order uncertainty to provide more precise estimates. However, both simulation modeling and probabilistic sensitivity analysis are rarely used together. The objective of this study was to explore uncertainty in controversial areas of the 2005 American Gastroenterology Association position statement on the management of dyspepsia.

METHODS

Individual sampling model, incorporating a second-order probabilistic sensitivity analysis.

POPULATION

US adult patients presenting in primary care with dyspepsia. Interventions compared: empirical acid suppression, test and treat for Helicobacter pylori, initial endoscopy, acid suppression then endoscopy, test and treat then proton pump inhibitor (PPI) then endoscopy.

OUTCOMES

Cost-effectiveness, quality-adjusted life years, and costs in US dollars from a societal perspective, measured over a 5-year period.

DATA SOURCES

mainly Cochrane meta-analyses.

RESULTS

Endoscopy was dominated at all ages by other strategies. PPI therapy was the most cost-effective strategy in 30-year-olds with a low prevalence of H. pylori. In 60-year-olds, H. pylori test and treat was the most cost-effective option.

CONCLUSIONS

Acid suppression alone was more cost-effective than either endoscopy or H. pylori test and treat in younger dyspepsia patients with a low prevalence of infection.

Helicobacter pylori and oesophageal cancer--not always protective

The mechanism of the positive association between atrophic gastritis and oesophageal squamous cell carcinoma

Gastro-oesophageal reflux disease

Gastro-oesophageal reflux disease refers to reflux of gastric contents into the oesophagus leading to oesophagitis, reflux symptoms sufficient to impair quality of life, or long-term complications. Transient relaxation of the lower oesophageal sphincter is believed to be the primary mechanism of the disease although the underlying cause remains uncertain. Obesity and smoking are weakly associated with the disease and genetic factors might be important. A negative association with Helicobacter pylori exists, but eradication of H pylori does not seem to cause reflux disease. Diagnosis is imprecise as there is no gold standard. Reflux symptoms are helpful in diagnosis but they lack sensitivity. Ambulatory oesophageal pH monitoring also seems to be insensitive despite high specificity. Empirical acid suppression with a proton-pump inhibitor (PPI) has reasonable sensitivity but poor specificity. Some evidence suggests that once patients develop the disease, severity is determined early and patients seem to continue with that phenotype long term. Unfortunately, most patients do not respond to life-style advice and require further therapy. H2 receptor antagonists and PPIs are better than placebo in oesophagitis, with a number needed to treat of five and two, respectively. In non-erosive reflux disease, acid suppression is better than placebo but the response rate is lower. Most patients need long-term treatment because the disease usually relapses. The role of endoscopic therapy is uncertain. Anti-reflux surgery is probably as effective as PPI therapy although there is a low operative mortality and morbidity.

Helicobacter pylori public health implications

Population Helicobacter pylori screening and treatment has the potential to dramatically reduce global gastric cancer mortality. There is overwhelming evidence that the infection is a major cause of distal gastric adenocarcinoma. There is also randomized controlled trial evidence that H. pylori eradication reverses or ameliorates histological changes in the gastric mucosa that are important in carcinogenesis. Preliminary randomized controlled trial data suggest that screening and treatment may reduce the risk of gastric cancer although the number of cancer cases was small. Population H. pylori screening and treatment will also reduce mortality from peptic ulcer complications and reduce the burden of dyspepsia in the community. The reduction in health service dyspepsia costs means that this could be the first programme to pay for itself. From a scientific perspective, we still have insufficient evidence to conclude the benefits of population H. pylori screening are greater than the possible harms and we need more randomized controlled trial data. From a public health perspective however, sometimes screening programmes are developed with imperfect information. The medical community should be consistent and if we are instituting other population screening programmes without randomized controlled trial evidence then H. pylori testing and treatment should also be considered.