Table 2. Adjusted rate ratios for gastric cancer for exclusive users of PPIs and H2RAs compared with non-users of both PPI and H2RA, and for PPI users compared with H2RA users.

	Lag time=1 Yeara
	Person-years	Gastric cancers	IRR (95% CI)b
Unexposed	2 345 905	519	reference
PPI vs Unexposed
2+ Prescriptions	51 854	24	1.2 (0.8–2.0)
Years of follow-up
<1	13 316	10	2.3 (1.2–4.3)
1	10 391	3	0.8 (0.2–2.4)
2–4	19 363	4	0.5 (0.2–1.4)
5+	8783	7	2.3 (1.2–4.3)
No. of prescriptions
2–4	30 588	8	0.8 (0.4–1.6)
5–14	13 851	9	1.6 (0.8–3.3)
15+	7415	7	2.1 (1.0–4.7)
H2RA vs Unexposed
2+ Prescriptions	81 256	30	1.2 (0.8–1.8)
Years of follow-up
<1	14 847	5	1.2 (0.5–2.8)
1	12 821	10	2.6 (1.4–4.9)
2–4	28 925	6	0.7 (0.3–1.5)
5+	24 663	9	1.1 (0.5–2.8)
No. of prescriptions
2–4	43 060	9	0.8 (0.4–1.5)
5–14	24 213	13	1.7 (0.9–2.9)
15+	13 984	8	1.6 (0.8–3.2)
PPI vs H2RA
2+ Prescriptions			1.3 (0.7–2.3)
Years of follow-up
<1			2.4 (0.7–8.0)
1			0.7 (0.2–3.0)
2–4			0.8 (0.2–3.3)
5+			1.8 (0.6–5.0)
No. of prescriptions
2–4			1.1 (0.4–3.2)
5–14			1.7 (0.7–4.5)
15+			1.4 (0.5–4.3)

Abbreviations: H2RA=histamine-2-antagonist; IRR=incidence rate ratio; PPI=proton pump inhibitor.

North Jutland County, Denmark (1990–2003).

^a1 year subtracted from diagnosis and censoring dates (except age and shift of treatment).

^bAdjusted for: age, gender, calendar period, gastroscopy (⩾1 year before censoring events), use of NSAIDs and H. pylori eradication.