Gastric and duodenal ulcer and their associated diseases.

Assessments of likely associations between ulcer and other diseases are hindered by the frequent lack of controls, by controls which are inadequate, and by inadequate descriptions of techniques used. The inherent biases in some of the techniques have also probably been insufficiently appreciated. Ulcer is common in the community and much of the evidence adduced to suggest ulcer/other-disease associations may well be describing oridinary ulcer frequency which has been underestimated. With such problems in mind, few of the proposed associations bear examination. Ulcer is probably unusually frequent in patients undergoing treatment for chronic renal failure. It is possibly more frequent in association with hyperparathyroidism and in cirrhotics, in cardiovascular disease (except hypertension), and in chronic respiratory disease. Evidence for other associations is not compelling.