CLINICAL QUESTION: Is H pylori associated with nonulcer dyspepsia, and if so, will eradication improve symptoms?
BACKGROUND: H pylori is associated with peptic ulcer disease, chronic gastritis, and other syndromes. The role of H pylori in nonulcer dyspepsia is less well defined. Many people have symptoms of dyspepsia, accounting for 3% to 5% of all primary care visits. Acid suppression therapy and motility agents have been the mainstay of treatment for empiric management of nonulcer dyspepsia. If H pylori is a cause of nonulcer dyspepsia, its eradication may reduce or remove symptoms. Since no study has been definitive, the authors undertook a pair of meta-analyses to address this question.
POPULATION STUDIED: The first meta-analysis was to investigate the possible association between H pylori and nonulcer dyspepsia. The authors identified 23 articles, involving more than 7000 patients. These studies were completed in Europe, Africa, Asia, and North America. The second part of this meta-analysis included only randomized trials testing whether eradication of H pylori would improve symptoms of nonulcer dyspepsia. The authors found 5 randomized trials of 778 patients from North America and Europe. Two of those studies had 1-year follow-up and used 3 agents to eradicate the H pylori. The other 3 studies followed patients for only 8 weeks and used a single agent to attempt eradication of H pylori. The latter 3 studies had lower overall quality scores.
STUDY DESIGN AND VALIDITY: These meta-analyses were reasonably well done, although the reported search strategy was somewhat limited. The authors did not include studies published in languages other than English or published only in abstract format. Their reported search strategy only included MEDLINE searches, although they may have searched references of selected papers. No assessment of potential publication biases was undertaken. The authors developed quality scores for each of the articles included, and they performed appropriate sensitivity analysis, testing whether study methods or quality affected the results. Overall, the quality scores of the included studies were not very high; the median score was only 41% of the best possible score. Most studies had reduced scores because of inadequate definition of dyspepsia and poor (or no) control for confounding.
OUTCOMES MEASURED: The authors created summary scores for studies and then combined them to form summary estimates. In the meta-analysis of association, the authors created an odds ratio (OR) for an association between H pylori and nonulcer dyspepsia. In the treatment meta-analysis, the OR represents the odds of improvement of nonulcer dyspepsia symptoms after H pylori treatment.
RESULTS: For the association between H pylori and nonulcer dyspepsia, a summary OR of 1.6 (95% confidence interval [CI], 1.4 - 1.8) was found. Of note, studies of lower quality showed a stronger association. In addition, studies using a weaker methodology (case-control) had a higher OR (OR = 2.0; 95% CI, 1.7 - 2.5) than the studies that used prevalence measures in the general population (OR = 1.3; 95% CI, 1.0 - 1.7). In the meta-analysis investigating potential benefit of H pylori eradication, the summary OR was 1.9 (95% CI, 1.3 - 2.6). Studies with 8-week follow-up and using a single agent found a much stronger association (OR = 15.4) than those that used a 1-year follow-up and 3 agents to eradicate H pylori (OR = 1.4; 95% CI, 1.0 - 2.3).
The summary ORs for the 2 parts of this study suggest a correlation between H pylori and nonulcer dyspepsia, and that eradication of H pylori would improve the symptoms of nonulcer dyspepsia. However, the studies with better designs tended to find a smaller association. Many studies had poor quality scores, and there is a substantial potential for systematic bias. In addition, 2 recent eradication studies with negative results were not included because they were published at nearly the same time as this study (see next POEM).1,2 For these reasons, it is possible the findings reported are spurious. It is likely that at best there is minimal benefit to eradicating H pylori in patients with nonulcer dyspepsia.