[Significance of the stool occult blood test in patients with thrombotic disease under treatment with low dose aspirin].

We encountered lower gastrointestinal bleeding in 16 patients taking a low dose of aspirin and examined the effect of low aspirin dose on the stool occult blood test in 49 thrombotic patients (mean: 76.7 +/- 9.6 years old) including 39 with cerebral infarction, 8 with ischemic heart disease and 2 with atrial fibrillation. The mean aspirin dosage was 81 mg/day over a period of 6-288 weeks (mean: 86.4 +/- 66.9 weeks). Positive occult blood test was seen in 16/49 (32.7%). Severe lower gastrointestinal bleeding was observed in one case (2%) with colon diverticulosis. Aspirin dosage per patient was significantly higher (p<0.01) in the occult blood test positive group (60.1 +/- 47.2 g) than in the occult blood test negative group (42.6 +/- 32.8 g). The positive ratio of occult blood test was significantly higher (p<0.01) in the aspirin and antithrombotic drugs-taking group (8/5; positive/negative) than in the aspirin-taking group (8/28; p/n), whereas it was not significant between the aspirin taking-group and aspirin not taking-group. The odds ratio between aspirin and antithrombotic drugs (warfarin, beraprost, cilostazol or ticlopidine)-taking group and the aspirin-taking group was 3.47 (p<0.05). A low dose of aspirin was associated with a positive occult blood test. Aspirin should be carefully administered when patient has a diverticle or is taking other antithrombotic drugs.