Table 3. Subgroup analysis by smoking status: hazard ratios (95% confidence intervals) for lung cancer incidence by daily coffee consumption.
| All Participants | Coffee intake | P-trend | P-interaction | |||
| No Coffee | <3 Cups/day | ≥3 Cups/day | ||||
| Men | 0.266 | |||||
| Never-smokers | ||||||
| Number of participants | 10,138 | 3,804 | 5,615 | 719 | — | — |
| Number of cases | 87 | 40 | 40 | 7 | — | — |
| Age, area | 1.00 | 0.75 (0.48–1.17) | 1.20 (0.53–2.71) | 0.587 | — | |
| Multivariate-adjusted | 1.00 | 0.81 (0.49–1.33) | 1.41 (0.58–3.46) | 0.940 | — | |
| Former smokers | ||||||
| Number of participants | 9,789 | 3,660 | 5,323 | 806 | — | — |
| Number of cases | 188 | 75 | 105 | 8 | — | — |
| Age, area | 1.00 | 1.11 (0.82–1.50) | 0.85 (0.41–1.78) | 0.802 | — | |
| Multivariate-adjusted | 1.00 | 1.25 (0.90–1.74) | 0.88 (0.40–1.95) | 0.461 | — | |
| Current smokers | ||||||
| Number of participants | 21,800 | 5,727 | 12,243 | 3,830 | — | — |
| Number of cases | 952 | 288 | 521 | 143 | — | — |
| Age, area | 1.00 | 1.04 (0.90–1.20) | 1.18 (0.96–1.46) | 0.155 | — | |
| Multivariate-adjusted | 1.00 | 1.12 (0.95–1.32) | 1.24 (0.99–1.57) | 0.058 | — | |
| Light smokers: pack-years ≤19.9a | ||||||
| Number of participants | 7,846 | 2,654 | 4,446 | 746 | — | — |
| Number of cases | 100 | 38 | 58 | 4 | — | — |
| Age, area | 1.00 | 1.14 (0.75–1.73) | 0.61 (0.21–1.73) | 0.876 | — | |
| Multivariate-adjusted | 1.00 | 1.35 (0.83–2.18) | 0.92 (0.31–2.68) | 0.500 | — | |
| Heavy smokers: pack-years ≥20.0a | ||||||
| Number of participants | 23,743 | 6,733 | 13,120 | 3,890 | — | — |
| Number of cases | 1,040 | 325 | 568 | 147 | — | — |
| Age, area | 1.00 | 1.08 (0.94–1.24) | 1.29 (1.05–1.58) | 0.023 | — | |
| Multivariate-adjusted | 1.00 | 1.16 (0.99–1.35) | 1.30 (1.04–1.63) | 0.014 | — | |
| Women | 0.243 | |||||
| Never-smokers | ||||||
| Number of participants | 42,155 | 14,374 | 24,458 | 3,323 | — | — |
| Number of cases | 375 | 147 | 204 | 24 | — | — |
| Age, area | 1.00 | 1.01 (0.81–1.25) | 1.14 (0.72–1.79) | 0.716 | — | |
| Multivariate-adjusted | 1.00 | 1.00 (0.79–1.28) | 1.13 (0.70–1.84) | 0.759 | — | |
| Current smokers | ||||||
| Number of participants | 2,600 | 645 | 1,337 | 618 | — | — |
| Number of cases | 61 | 14 | 35 | 12 | — | — |
| Age, area | 1.00 | 1.42 (0.76–2.67) | 1.39 (0.61–3.14) | 0.380 | — | |
| Multivariate-adjusted | 1.00 | 1.27 (0.66–2.45) | 1.38 (0.58–3.28) | 0.441 | — | |
Multivariate analyses were adjusted for the following factors at baseline: age (continuous); gender; PHC area; body-mass index (<18.5, 18.5–24.9, 25.0–29.9, and ≥30 kg/m2); smoking status (never, former: <10, 10–19, and ≥20 years of smoking cessation, current: 1–19, 20–29, 30–39, 40–49, 50–59, ≥60 pack-years); physical activity (almost never, <3 days/month, 1–2 days/week, 3–4 days/week, and almost everyday); alcohol consumption (never/former, <1 time/week, <23, 23–45, 46–68, 69–91, and >92 g of ethanol/day); consumption of green tea, Chinese tea, and black tea (almost never, <1 time/week, and >1 cup/day); energy-adjusted intake of fruit, vegetables, and isoflavone (continuous).
aModel included current and former smokers. Pack-years is the number of cigarette packs (assuming 20 cigarettes per pack) smoked per day, multiplied by years of consumption.