What to do about Helicobacter pylori? A decision analysis of its implication on public health

Agreement of decision analyses and subsequent clinical studies in infectious diseases

PURPOSE

Decision analysis techniques can compare management strategies when there are insufficient data from clinical studies to guide decision making. We compared the outcomes of decision analyses and subsequent clinical studies in the infectious disease literature to assess the validity of the conclusions of the decision analyses.

METHODS

A search strategy to identify decision analyses in infectious disease topics published from 1990 to 2005 was developed and performed using PubMed. Abstracts of all identified articles were reviewed, and infectious disease-related decision analyses were retained. Subsequent clinical trials and observational studies that corresponded to these decision analyses were identified using prespecified search strategies. Clinical studies were considered a match for the decision analysis if they assessed the same patient population, intervention, and outcome. Agreement or disagreement between the conclusions of the decision analysis and clinical study were determined by author review.

RESULTS

The initial PubMed search yielded 318 references. Forty decision analyses pertaining to 29 infectious disease topics were identified. Of the 40, 16 (40%) from 13 infectious disease topics had matching clinical studies. In 12 of 16 (75%), conclusions of at least 1 clinical study agreed with those of the decision analysis. Three of the 4 decision analyses in which conclusions disagreed were from the same topic (management of febrile children).

CONCLUSIONS

There was substantial agreement between the conclusions of decision analyses and clinical studies in infectious diseases, supporting the validity of decision analysis and its utility in guiding management decisions.

The health economics of Helicobacter pylori infection

Economic considerations are becoming increasingly important as health care becomes more expensive. Evidence for effectiveness is usually gained from randomised controlled trials (RCTs) but often there is insufficient evidence of the costs of alternative strategies in trials. Often, therefore, economic models are needed to extrapolate data from a variety of sources to give an indication of which strategy is cost effective. Helicobacter pylori (H. pylori) testing and treating in a wide variety of upper gastrointestinal diseases is a good example of the application of economic analyses to health care interventions. H. pylori eradication in peptic ulcer disease is very effective with systematic reviews giving a number needed to treat of around two compared to no therapy. RCTs have also suggested that treating H. pylori is also more effective and less expensive than continuous H(2) receptor antagonist therapy and is therefore the dominant strategy in treating peptic ulcer disease. The impact of H. pylori eradication in infected patients with functional dyspepsia is less dramatic, with systematic reviews suggesting a number needed to treat of 14. Economic models suggest that in Europe H. pylori eradication is cost-effective compared to offering no treatment (e.g. in the UK we can be 95% certain this approach is cost effective if you are willing to pay $51/month free from dyspepsia). In the USA it is less certain that this is a cost-effective approach due to the higher cost of eradication therapy. H. pylori test and treat has been proposed as an alternative to early endoscopy in patients with uninvestigated dyspepsia. We have conducted an individual patient data meta-analysis of five RCTs that has addressed the cost effectiveness of this approach. Endoscopy was slightly more effective than H. pylori test and treat at relieving dyspepsia at one year but was not cost-effective as it cost $9000/dyspepsia cure at one year. Population H. pylori test and treat has been proposed as a strategy to prevent noncardia gastric cancer. RCTs have suggested this approach may be cost saving but more data are needed on whether H. pylori eradication will reduce gastric cancer mortality before this strategy can be recommended.

The benefit of negative tests in non-ulcer dyspepsia

OBJECTIVES

Negative diagnostic tests are usually evaluated by their ability to advance a diagnostic search, or they are considered redundant expenditures in establishing a definitive diagnosis. It has remained difficult to assess their benefit in terms of their own merit and the reassurance that they provide to a patient. The aim of the present study is to develop a mathematical model for quantifying the impact of diagnostic tests on a patient's health-related quality of life (HRQL).

METHODS

An influence diagram is used to model how non-ulcer dyspepsia (NUD) and its medical care affect HRQL. Diagnostic tests and medical therapy benefit HRQL by alleviating fear of disease and NUD symptoms. Medical care can also adversely affect HRQL, lead to expenses in time and money, and compromise a patient's sense of autonomy. HRQL is modeled as the focal point of multiple influences detracting from its value.

RESULTS

Negative diagnostic tests can improve HRQL in NUD. The improvement of HRQL by diagnostic tests depends on a multitude of individual influences and the interactions between them, such as the severity of NUD symptoms andfear of disease, as well as the impact of medical care itself on HRQL. If a patient harbors a strong fear of serious disease or cancer, more extensive testing is likely to improve the patient's well-being and appears a worthwhile endeavor. Other patients, however, would be served perfectly well by empirical therapy only. For the vast majority of subjects with NUD who never seek medical advice, the unpleasantness of the disease itself does not outweigh the anticipated downside of obtaining medical care.

CONCLUSION

The analysis illustrates the applicability of the influence diagram in modeling disease behavior. This method helps to assess the benefit of negative tests beyond their means of generating information.