Table 3.

Associations between regular use of aspirin and risk of pancreatic cancer, according to stage of disease and gender^a

Aspirin use	No. of case patientsb n=761	No. of control subjectsb n=794	OR (95% CI)	P
Local stage case patients vs controls:
Ever use
No	90	651	Ref.
Yes	13	143	0.61 (0.33–1.15)	.13
Duration of use, y	2.04	4.06	0.81 (0.67–0.98)	.031
Regional stage case patients vs controls:
Ever use
No	386	651	Ref.
Yes	52	143	0.56 (0.39–0.80)	.0013
Duration of use, y	3.65	4.06	0.92 (0.86–0.99)	.019
Distant stage case patients vs controls:
Ever use
No	198	651	Ref.
Yes	22	143	0.46 (0.28–0.75)	.0020
Duration of use, y	4.36	4.06	0.93 (0.85–1.02)	.11
Male subjects:
Ever use
No	378	377	Ref.
Yes	57	83	0.64 (0.44–0.94)	.023
Duration of use, y	3.68	4.23	0.93 (0.87–1.00)	.045
Female subjects:
Ever use
No	296	274	Ref.
Yes	30	60	0.42 (0.26–0.67)	10−3.5
Duration of use, y	3.41	3.82	0.89 (0.80–0.99)	.028

^aUnconditional logistic regression models were used to obtain the odds ratios (ORs) and 95% confidence intervals (CIs). All models were adjusted for age at interview (continuous), sex, education category (continuous), body mass index at age 21 (continuous), years of cigarette smoking (continuous), number of cigarettes per day (continuous), H. pylori CagA seropositivity, ABO blood group A vs non-A, and history of diabetes mellitus more than 3 years in the past. Each row in the table is a separate adjusted model.

^bNumbers of subjects for the category variables. For the duration variables, these columns give the mean durations among aspirin ever users; the ORs are per one year of duration, and the P-values represent trend associations.