[Risk factors for gastrointestinal bleeding associated with low-dose aspirin]

Low-dose aspirin is the cause of gastro-intestinal and bleeding complications. Different factors may increase the gastro-intestinal (GI) toxicity associated with aspirin. The aim of this review is to attempt to describe these factors.

This review is based on an analysis of 24 randomized GI, cardiovascular and neurological studies and 8 case-control and cohort, follow-up studies evaluating GI and bleeding risk factors associated with the ingestion of aspirin at doses of less than 500 mg/day. These studies have been selected based on specific criteria from all works published from 1983 to 2003 (PubMed).

The GI toxicity of low-dose aspirin appears to be dose-dependent, apparently starting with 10 mg/day, but this observation has not been confirmed by all studies. The "protective" effect of gastro-resistant coating is debatable. The GI risk is enhanced in the elderly and in particular appears related to concomitant disorders, specifically cardiovascular and neurological disorders, but few studies make it possible to confirm this. A previous history of ulcer or GI bleeding are identified risk factors for GI bleeding, but few studies have been conducted on patients treated with low-dose aspirin to confirm this. Other platelet-inhibiting and anti-coagulant agents potentiate the gastro-intestinal lesional and bleeding risk associated with low-dose aspirin. GI complications are more frequent if aspirin is given in combination with conventional NSAIDs or steroids. In the case of concomitant prescription of low-dose aspirin and an NSAID, the use of a coxib may be considered, but studies are still necessary to evaluate the usefulness of their combination use with low-dose aspirin. In the future, other better tolerated NSAIDs (NO releasing NSAIDs, zwitterion complexes) will be developed. Ongoing studies evaluate the protective risk of misoprostol and proton pump inhibitors in patients at risk for a GI adverse effects, receiving low-dose aspirin.

The GI risk induced by low-dose aspirin exists and may be increased by different factors related, first to the patient, and second to certain concomitant treatments. Patients at risk must be screened in order to plan a prophylactic strategy. However to date, no compound has been registered for prophylactic treatment of gastro-intestinal risk induced by low-dose aspirin.