Table 3.

Relation between aspirin dose and risk of UGIB and perforation among current users as compared to non-use

	All cases	Controls	Adjusted RR*
	(N=2,105)	(N=11,500)	(95%CI)
Daily dose as instructed
75 mg	141	420	1.9 (1.6-2.4)
150 mg	84	245	2.0 (1.5-2.6)
300 mg$	54	163	2.0 (1.4-2.8)
600 + mg	8	9	4.0 (1.4-11.5)
Average daily dose +
<50 mg (irregular use)	4	29	0.7 (0.2-2.0)
51-111	135	383	2.1 (1.7-2.6)
112-225	91	258	1.9 (1.5-2.5)
226-400	48	151	2.0 (1.4-2.9)
> 400	9	16	3.1 (1.3-7.5)

^* Adjusted for sex, age, calendar year, antecedents of gastrointestinal disorders, smoking status, alcohol consumption and use of NSAIDs, anticoagulants, steroids, SSRIs and paracetamol. Additional adjustment for use of antiulcer drugs (antacids, H2-blockers and omeprazol) did not change the estimates. $ Five cases and three controls taking 300 mg in alternate days were included in this category. Assigning those patients to the 150-mg category hardly modified the results. + Calculated by dividing the number of tablets supplied over the treatment period. For 161 patients (51 (18%) cases and 110 (13%) controls) less than 3 prescriptions of aspirin were written, therefore the instructed dose was still considered in these patients.