Epidemiological evidence for the association of aspirin and acute gastrointestinal bleeding.

Epidemiological evidence for the association of aspirin and acute gastrointestinal bleeding Although Hurst' claimed that the intake of aspirin was the likely cause of upper gastrointestinal haemorrhage in half of all those patients remaining, once those with known causes, such as chronic ulceration, had been excluded from consideration, little interest was shown in this suggested association until more recently when Muir and Cossar2 found a higher aspirin con- sumption in a group of individuals suffering from haematemesis or melaena compared with that of a control group. The effects of aspirin on the gastro- intestinal tract have also been explored in animals by various experimental pro- cedures and in man by clinical physiological studies, usually designed to compare the degree of occult or microbleeding inducible by aspirin and other drugs, in groups of individuals with or without a history of upper gastroin- testinal haemorrhage, but the critical evidence in establishing an association between aspirin consumptionand acute haemorrhage must come from epidemi- ological studies. That experimental studies mayeven be misleading is illustrated by the evidence that salicylate compounds can cause hypoprothrombinaemia, a prolonged bleeding time3, and platelet aggregation4. Animal studies have also shown that administering systemic salicylates, usually in large doses, can cause gastric erosions and bleeding 5,6,7. However, when acetylsalicylate was given intravenously in man, there was no evidence of any tendency to bleeding when the dose was kept within the usual therapeutic range8.