Table 4.

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

	Cases (n = 152) n (%)	Controls (n = 1,000) n (%)	Odds ratioa (95 % CI)	P value
ASA
Non-use	29 (19.1)	186 (18.6)	1 (−)
Current use	107 (70.4)	753 (75.3)	1.31 (0.76–2.27)	0.33
Duration
< 1 month	8 (5.3)	32 (3.2)	0.92 (0.29–2.91)	0.89
1–12 months	38 (25.0)	191 (19.1)	1.26 (0.62–2.57)	0.53
≥ 1 year	61 (40.1)	530 (53.0)	1.39 (0.72–2.67)	0.33
Dose
75 mg/day	98 (64.5)	653 (65.3)	1.40 (0.80–2.43)	0.23
150 mg/day	6 (3.9)	85 (8.5)	0.53 (0.18–1.59)	0.26
300 mg/day	3 (2.0)	15 (1.5)	2.47 (0.60–10.24)	0.21
Recent use	10 (6.6)	24 (2.4)	4.33 (1.61–11.66)	<0.01
Past use	6 (3.9)	37 (3.7)	0.85 (0.30–2.44)	0.76
Clopidogrel
Non-use	96 (63.2)	765 (76.5)	1 (−)
Current use	48 (31.6)	164 (16.4)	2.17 (1.35–3.49)	<0.01
Duration
< 1 month	10 (6.6)	11 (1.1)	5.76 (1.82–18.27)	<0.01
1–12 months	25 (16.4)	73 (7.3)	2.14 (1.10–4.18)	0.03
≥ 1 year	13 (8.6)	80 (8.0)	1.80 (0.85–3.80)	0.12
Dose
75 mg/day	46 (30.3)	154 (15.4)	2.22 (1.38–3.59)	<0.01
≥ 150 mg/day	2 (1.3)	10 (1.0)	1.19 (0.22–6.31)	0.84
Recent use	2 (1.3)	13 (1.3)	1.12 (0.22–5.64)	0.89
Past use	6 (3.9)	58 (5.8)	0.64 (0.25–1.68)	0.37
Dual antiplatelet therapy
Non-use of both ASA and clopidogrel	18 (11.8)	119 (11.9)	1 (−)
Current use of both ASA and clopidogrel	36 (23.7)	100 (10.0)	2.42 (1.09–5.36)	0.03
Current ASA use and non-current clopidogrel use	71 (46.7)	653 (65.3)	0.91 (0.46–1.80)	0.78
Current clopidogrel use and non-current ASA use	12 (7.9)	64 (6.4)	1.29 (0.52–3.20)	0.58

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

^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