Table 2.
Association between regular aspirin use and incident pancreatic cancer.
| HPFS | NHS | Combined Population | ||||
|---|---|---|---|---|---|---|
| Nonregular users | Regular users | Nonregular users | Regular users | Nonregular users | Regular users | |
| Current Exposure* | ||||||
| No. cases | 214 | 201 | 379 | 328 | 593 | 529 |
| Person-years | 585,954 | 501,314 | 1,899,575 | 1,227,923 | 2,485,529 | 1,729,236 |
| Age-adjusted RR (95% CI) | 1 | 0.91 (0.75, 1.10) | 1 | 1.01 (0.87, 1.18) | 1 | 0.99 (0.88, 1.11) |
| Multivariable RR (95% CI)§ | 1 | 0.87 (0.71, 1.06) | 1 | 0.99 (0.85, 1.15) | 1 | 0.95 (0.84, 1.07) |
| Latency Exposure* | ||||||
| No. cases | 163 | 165 | 357 | 288 | 520 | 453 |
| Person-years | 443,434 | 336,911 | 1,529,058 | 875,400 | 1,972,492 | 1,212,311 |
| Age-adjusted RR (95% CI) | 1 | 1.08 (0.87, 1.35) | 1 | 1.14 (0.98, 1.34) | 1 | 1.14 (1.00, 1.29) |
| Multivariable RR (95% CI)§ | 1 | 1.03 (0.82, 1.29) | 1 | 1.12 (0.95, 1.31) | 1 | 1.09 (0.96, 1.24) |
| Baseline Exposure* | ||||||
| No. cases | 159 | 144 | 365 | 209 | 524 | 353 |
| Person-years | 456,511 | 323,807 | 1,818,540 | 891,565 | 2,275,051 | 1,215,372 |
| Age-adjusted RR (95% CI) | 1 | 1.08 (0.86, 1.36) | 1 | 1.14 (0.96, 1.36) | 1 | 1.14 (1.00, 1.31) |
| Multivariable RR (95% CI)§ | 1 | 1.02 (0.81, 1.29) | 1 | 1.14 (0.96, 1.35) | 1 | 1.10 (0.95, 1.26) |
CI, confidence interval; HPFS, Health Professionals Follow-up Study; NHS, Nurses’ Health Study; RR, relative risk
Current exposure, aspirin use obtained from the most recent questionnaire cycle; Latency exposure, 6–8 year latency period for reported aspirin exposure; Baseline exposure, aspirin use obtained from baseline questionnaires (HPFS 1992; NHS 1980).
Multivariate models conditioning on age (months) and questionnaire cycle and adjusted for sex/cohort, race (White, Black, other, unknown), BMI in kg/m2 (<25.0, 25.0–29.9, 30.0–34.9, ≥35.0, missing), diabetes mellitus (yes/no), smoking in pack-years (never, <5, 5–19, 20–39, ≥40, missing), alcohol intake in grams/day (0, 0.1–4.9, 5.0–14.9, 15.0–29.9, ≥30.0, missing), multivitamin use (yes/no), physical activity (quintiles by sex), and regular non-aspirin NSAID use (yes/no/missing).