Table 3.
HRs for total and cause-specific mortality associated with cigarette smoking in the cohort (n = 7,665), 1960–2012
| Cause of death (ICD-10) | Ever/Never smokers | HR for per 1 pack-year increase in smoking | HRs for smoking intensity versus non-smokinga | ||
|---|---|---|---|---|---|
| < 26.08 pack-years | ≥26.08 pack-years | p-trendb | |||
| Malignant neoplasm (C00-C97) | 615/174 | 1.007 (1.004, 1.011) | 1.689 (1.364, 2.090) | 1.698 (1.392, 2.072) | < 0.001 |
| Malignant neoplasm of oesophagus (C15) | 46/20 | 0.997 (0.984, 1.010) | 0.944 (0.487, 1.827) | 0.979 (0.535, 1.790) | 0.956 |
| Malignant neoplasm of stomach (C16) | 72/32 | 0.990 (0.979, 1.001) | 1.207 (0.746, 1.952) | 0.617 (0.372, 1.022) | 0.050 |
| Malignant neoplasm of liver and intrahepatic bile ducts (C22) | 120/32 | 0.991 (0.982, 1.000) | 2.142 (1.379, 3.326) | 0.968 (0.609, 1.538) | 0.511 |
| Lung cancer (C33-C34) | 228/34 | 1.023 (1.019, 1.028) | 1.883 (1.111, 3.192) | 6.115 (3.908, 9.570) | < 0.001 |
| Certain infectious and parasitic diseases (A00-B99, J65) | 62/27 | 0.982 (0.970, 0.995) | 1.504 (0.893, 2.533) | 0.633 (0.358, 1.122) | 0.097 |
| Respiratory tuberculosis (A15-A16, J65) | 43/15 | 0.991 (0.976, 1.005) | 1.756 (0.889, 3.471) | 1.009 (0.503, 2.025) | 0.905 |
| Cardiovascular disease (I00-I52, I70-I99) | 259/113 | 1.002 (0.997, 1.007) | 1.546 (1.178, 2.029) | 1.012 (0.774, 1.324) | 0.885 |
| Ischaemic heart disease (I20-I25) | 150/69 | 1.005 (0.998, 1.011) | 1.173 (0.810, 1.699) | 1.097 (0.782, 1.539) | 0.632 |
| Pulmonary heart disease (I26-I27) | 51/15 | 1.007 (0.995, 1.019) | 3.097 (1.608, 5.965) | 1.365 (0.675, 2.760) | 0.507 |
| Cerebrovascular disease (I60-I69) | 258/130 | 1.000 (0.995, 1.005) | 1.054 (0.801, 1.389) | 0.973 (0.757, 1.249) | 0.797 |
| Disease of the respiratory system (J00-J99) | 246/78 | 1.007 (1.002, 1.012) | 1.473 (1.068, 2.031) | 1.701 (1.275, 2.268) | < 0.001 |
| Pneumoconiosis (J60-J65) | 93/17 | 1.008 (0.999, 1.017) | 2.928 (1.638, 5.237) | 2.458 (1.394, 4.334) | 0.005 |
| Chronic lower respiratory disease (J40-J47) | 104/38 | 1.010 (1.002, 1.017) | 1.058 (0.633, 1.768) | 1.745 (1.143, 2.665) | 0.006 |
| Disease of the digestive system (K00-K93) | 63/32 | 0.978 (0.966, 0.990) | 1.369 (0.843, 2.223) | 0.380 (0.212, 0.684) | 0.001 |
| Fibrosis and cirrhosis of liver (K74) | 42/21 | 0.975 (0.960, 0.991) | 1.305 (0.721, 2.362) | 0.360 (0.174, 0.748) | 0.006 |
| External causes of morbidity and mortality (V01-Y98) | 120/73 | 0.960 (0.950, 0.970) | 0.980 (0.706, 1.360) | 0.262 (0.170, 0.405) | < 0.001 |
| All diseases (A00-Y98) | 1917/897 | 1.001 (0.999, 1.003) | 1.176 (1.060, 1.305) | 1.056 (0.958, 1.163) | 0.413 |
HRs were calculated by using Cox proportional hazards models, which included the duration of follow-up as time variable and were adjusted for gender, year at hire (five categories: 1955 or earlier, 1956–1960, 1961–1965, 1966–1970, 1971 or later), age at hire (continuous), and silica exposure (pack-years, continuous). Pneumoconiosis mortality risks were estimated only among silica-exposed workers
aThe categorical analyses were conducted on the basis of smoking intensity, including non-smoking, < 26.08 pack-years and ≥ 26.08 pack-years, with 26.08 pack-years as the median point for smoking intensity. The reference category was defined as the non-smoking level
bEvaluated by including the median exposure values within each smoking intensity category as a continuous variable in the model