Lancet
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Comparative Study
Can overall results of clinical trials be applied to all patients?
It is generally assumed that the overall results of a clinical trial are generalisable to all patients in the trial and all similar future patients; in other words, that the relative treatment effect in individual patients is similar to the overall trial result. Although this assumption underpins the application of trial results to clinical practice, it has rarely been tested. ⋯ There was significant heterogeneity of relative treatment effect in both trials, resulting in substantial variation in absolute treatment effect with predicted baseline risk. Although, on average, the application of overall trial results to all patients will do more good than harm, a knowledge of the association between relative treatment effect and absolute baseline risk will increase the cost-effectiveness of healthcare interventions by identifying those patients in whom treatment is ineffective and those patients who are most likely to benefit.
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Chronic Helicobacter pylori gastritis has been put forward as a risk factor for development of gastric mucosal atrophy and gastric cancer. The purpose of our study was to investigate the long-term effects of H pylori gastritis on the gastric mucosa. We prospectively studied 49 subjects negative for H pylori and 58 positive subjects for a mean follow-up of 11.5 years (range 10-13 years). ⋯ The proportion of atrophic gastritis in the study population showed an annual increase of 1.15% (0.5-1.8%). We conclude that H pylori infection is a significant risk factor for development of atrophic gastritis and intestinal metaplasia. Our findings support strongly the causative role of this infection in gastric carcinogenesis.