Table 3.
Hazard ratios (95% confidence intervals) for bladder cancer according to coffee intake in the NIH-AARP Diet and Health Study by smoking (N = 453 935)a
| Smoking subgroup (n) | Cigarettes/day (n) | 1 cup/day increase | Coffee Intake (cups/day) | P-trend | P smoking-heterogeneityf | ||||
|---|---|---|---|---|---|---|---|---|---|
| None (ref.)b | ≤1 | 2 to 3 | ≥4 | ||||||
| Never smoker (n=156 448)a | No. cases | 890 | 151 | 336 | 337 | 66 | 0.03 | ||
| HR (95% CI)c | 1.01 (0.96–1.06) | 1.00 | 0.91 (0.75–1.11) | 1.03 (0.85–1.26) | 0.87 (0.65–1.17) | 0.84 | |||
| Former smoker (n=231 084) | Overall | No. cases | 3676 | 184 | 1095 | 1709 | 688 | ||
| HR (95% CI)c,d,e | 1.02 (1.00–1.05) | 1.00 | 1.15 (0.98–1.34) | 1.14 (0.98–1.33) | 1.23 (1.04–1.33) | 0.07 | |||
| Quit ≥ 10 years ago | ≤20 (104 492) | No. cases | 1256 | 73 | 457 | 565 | 161 | ||
| HR (95% CI)c,d | 1.02 (0.98–1.06) | 1.00 | 1.20 (0.93–1.53) | 1.14 (0.89–1.46) | 1.20 (0.91–1.58) | 0.83 | |||
| >20 (72 974) | No. cases | 1431 | 74 | 402 | 660 | 295 | |||
| HR (95% CI)c,d | 1.02 (0.99–1.06) | 1.00 | 1.12 (0.88–1.44) | 1.08 (0.85–1.38) | 1.23 (0.95–1.59) | 0.18 | |||
| Quit 5 to 9 years ago | ≤20 (15 620) | No. cases | 210 | 10 | 54 | 110 | 36 | ||
| HR (95% CI)c,d | 1.06 (0.97–1.17) | 1.00 | 0.90 (0.46–1.77) | 1.18 (0.61–2.27) | 1.17 (0.58–2.39) | 0.18 | |||
| >20 (18 304) | No. cases | 406 | 14 | 91 | 203 | 98 | |||
| HR (95% CI)c,d | 1.02 (0.96–1.09) | 1.00 | 1.04 (0.59–1.83) | 1.17 (0.68–2.03) | 1.13 (0.64–1.99) | 0.53 | |||
| Quit ≥ 1 to 4 years ago | ≤20 (9778) | No. cases | 148 | 3 | 42 | 72 | 31 | ||
| HR (95% CI)c,d | 1.07 (0.96–1.18) | 1.00 | 2.67 (0.82–8.65) | 2.83 (0.89–9.05) | 2.97 (0.90–9.77) | 0.31 | |||
| >20 (9916) | No. cases | 225 | 10 | 49 | 99 | 67 | |||
| HR (95% CI)c,d | 1.01 (0.93–1.10) | 1.00 | 1.02 (0.51–2.02) | 0.96 (0.50–1.85) | 1.06 (0.54–2.09) | 0.76 | |||
| Current smoker (n=66 403) | Overall | No. cases | 1262 | 41 | 166 | 588 | 467 | ||
| HR (95% CI)c,d | 1.05 (1.02–1.09) | 1.00 | 0.91 (0.64–1.28) | 1.33 (0.97–1.83) | 1.32 (0.95–1.81) | 0.001 | |||
| ≤20 (42 980) | No. cases | 731 | 25 | 120 | 361 | 225 | |||
| HR (95% CI)c,d | 1.05 (1.00–1.10) | 1.00 | 0.95 (0.62–1.46) | 1.32 (0.88–1.99) | 1.31 (0.86–1.98) | 0.01 | |||
| >20 (23 423) | No. cases | 531 | 16 | 46 | 227 | 242 | |||
| HR (95% CI)c,d | 1.05 (1.00–1.11) | 1.00 | 0.83 (0.47–1.47) | 1.34 (0.80–2.23) | 1.32 (0.80–2.20) | 0.02 | |||
Participants who reported never smoking cigarettes but who reported smoking pipes/cigars (n= 15 112) were excluded from this analysis
Referent group was non-drinkers of coffee
Adjusted for age at study baseline (continuous), sex, race/ethnicity (non-Hispanic White, non-Hispanic Black, Hispanic, or Asian/Pacific Islander/American Indian/Alaskan Native), body mass index (<18.5, 18.5 to <25, 25 to <30, or ≥30 kg/m2), level of education (≤ high school graduate, some college, or college graduate), alcohol consumption (0, <1, 1–2, or ≥3 drinks/day), self-reported general health status (excellent/very good, good, or fair/poor), total energy intake (kcal/day, continuous), nutrient density-adjusted fruit intake (servings/day, continuous), nutrient-density-adjusted vegetable intake (servings/day, continuous), supplement use (yes or no), physical activity (never/rarely, 1–3 times/month, 1–2 times/week, 3–4 times/week, ≥5 times/week), history of diabetes (yes or no), and family history of cancer (yes or no)
Additionally adjusted for having ever smoked pipes or cigars (yes or no), number of cigarettes smoked per day (1–10, 11–20, 21–30, 31–40, 41–60, or ≥60)
Additionally adjusted for time since quitting (≥1 to 4, 5 to 9, or ≥10 years before baseline)
P-value for likelihood ratio test comparing models with and without cross-product terms for 3-level smoking variable (never, former, or current) and continuous coffee drinking variable