The Helicobacter pylori theory and duodenal ulcer disease. A case study of the research process

To describe the medical research process from the time of the generation of a new theory to its implementation in clinical practice. The Helicobacter pylori (H. pylori) theory, i.e. the theory that H. pylori plays a significant causal role in duodenal ulcer disease was chosen as a case.

Abstracts from 1984 to 1993, identified in the CD-Rom, Medline system, ("Silverplatter"), using the search terms Campylobacter pylori and Helicobacter pylori, and reviews and editorials about H. pylori in some of the most widespread clinical journals.

2204 papers on H. pylori were published, of which 64% (1,403) were original articles. Of these, 30% (415/1,403) were descriptive clinical studies, 5% (64) were epidemiological studies, 33% (459) were laboratory studies of disease mechanisms, 8% (112) were therapeutic intervention studies, and 24% (336) concerned diagnostic and therapeutic techniques. A total of 204 of the clinical studies addressed duodenal ulcer disease. Of these, 72% (147) were cross-sectional studies, 3% (7) were observational cohort studies and 25% (50) were therapeutic intervention studies. Thirty-one editorials and reviews concerning the etiological role of H. pylori in duodenal ulcer disease had been published in some of the most widespread clinical journals. In half of the papers the authors were convinced of the causal role of H. pylori in duodenal ulcer disease, while in the remainder they were sceptical. In seven cases the authors stated which patients should be selected for H. pylori eradication treatment.

Descriptive clinical studies and laboratory studies of disease mechanisms were the prevailing types of research about H. pylori. Comparatively few therapeutic intervention studies were done; this fact may have hampered the acceptance of the H. pylori theory and the introduction of eradication therapy in clinical practice.