Table 3.

Effect of low-dose ASA and clopidogrel on the risk of LGIB

	Cases (n = 316) n (%)	Controls (n = 2,000) n (%)	Odds ratioa (95 % CI)	P value
ASA
Non-use	74 (23.4)	370 (18.5)	1 (−)
Current use	222 (70.3)	1502 (75.1)	0.96 (0.68–1.35)	0.80
Duration
< 1 month	11 (3.5)	65 (3.3)	0.79 (0.35–1.80)	0.57
1–12 months	97 (30.7)	441 (22.1)	1.20 (0.79–1.82)	0.40
≥ 1 year	114 (36.1)	996 (49.8)	0.83 (0.56–1.22)	0.34
Dose
75 mg/day	193 (61.1)	1286 (64.3)	0.96 (0.68–1.36)	0.81
150 mg/day	22 (7.0)	178 (8.9)	0.90 (0.51–1.57)	0.70
300 mg/day	7 (2.2)	38 (1.9)	1.30 (0.52–3.21)	0.57
Recent use	10 (3.2)	59 (3.0)	1.12 (0.51–2.44)	0.77
Past use	10 (3.2)	69 (3.5)	0.76 (0.36–1.60)	0.47
Clopidogrel
Non-use	200 (63.3)	1529 (76.5)	1 (−)
Current use	95 (30.1)	318 (15.9)	1.86 (1.34–2.57)	<0.01
Duration
< 1 month	9 (2.8)	25 (1.3)	2.40 (0.94–6.13)	0.07
1–12 months	44 (13.9)	148 (7.4)	1.51 (0.97–2.36)	0.07
≥ 1 year	42 (13.3)	145 (7.3)	2.12 (1.37–3.27)	<0.01
Dose
75 mg/day	84 (26.6)	286 (14.3)	1.82 (1.30–2.55)	<0.01
≥ 150 mg/day	11 (3.5)	32 (1.6)	2.15 (1.01–4.58)	0.05
Recent use	8 (2.5)	40 (2.0)	1.30 (0.58–2.94)	0.52
Past use	13 (4.1)	113 (5.7)	0.80 (0.43–1.48)	0.47
Dual antiplatelet therapy
Non-use of both ASA and clopidogrel	40 (12.7)	237 (11.9)	1 (−)
Current use of both ASA and clopidogrel	57 (18.0)	190 (9.5)	1.63 (0.95–2.81)	0.08
Current ASA use and non-current clopidogrel use	165 (52.2)	1312 (65.6)	0.84 (0.54–1.32)	0.46
Current clopidogrel use and non-current ASA use	38 (12.0)	128 (6.4)	1.56 (0.88–2.74)	0.13

ASA acetylsalicylic acid, CI confidence interval, LGIB lower gastrointestinal bleeding, NSAID non-steroidal anti-inflammatory drug, PCP primary care physician, PPI proton pump inhibitor

^aAdjusted according to age, sex, calendar year, length of follow-up, health services utilization (PCP visits, referrals and hospitalizations), smoking, type of coronary event, history of peptic ulcer disease and use of PPIs, ASA, clopidogrel, NSAIDs and warfarin