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Table 3 HRs for total and cause-specific mortality associated with cigarette smoking in the cohort (n = 7,665), 1960–2012

From: Combined effect of silica dust exposure and cigarette smoking on total and cause-specific mortality in iron miners: a cohort study

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

  1. 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
  2. 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
  3. bEvaluated by including the median exposure values within each smoking intensity category as a continuous variable in the model
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Environmental Health

ISSN: 1476-069X