Table 1 Demographics of cohort members at start of follow-up (1959)
CharacteristicEngineers/brakemenUnexposedTotal
Whole cohort
n21 234943730 671
Mean (SD)
    Age at hire31.4 (5.5)32.7 (5.9)31.8 (5.6)
    Age in 195947.8 (5.4)48.7 (5.7)48.1 (5.5)
    Pack–years*43.3 (4.1)40.9 (3.7)42.1 (4.1)
Cigarette smoking (%)†
    Never2739 (12.9)1680 (17.8)4419 (14.4)
    Current16 329 (76.9)6587 (69.8)22 916 (74.7)
    Former2166 (10.2)1170 (12.4)3336 (10.9)
COPD deaths12194641683
Hired <1945
n17 321678524 106
Mean (SD)
    Age at hire31.1 (5.5)31.9 (5.8)31.3 (5.6)
    Age in 195948.1 (5.4)49.2 (5.7)48.4 (5.5)
    Pack–years*43.3 (4.1)40.8 (3.8)42.1 (4.1)
Cigarette smoking (%)†
    Never12.917.515.2
    Current76.870.077.4
    Former10.312.511.4
COPD deaths10023491351
Hired ⩾1945
n391326526565
Mean (SD)
    Age at hire32.9 (5.1)34.5 (5.7)33.5 (5.5)
    Age in 195946.4 (5.2)47.4 (5.6)46.8 (5.4)
    Pack–years*43.1 (4.6)40.9 (3.8)42.0 (4.3)
Cigarette smoking (%)†
    Never12.918.415.7
    Current77.169.373.2
    Former10.012.311.1
COPD deaths217115332
  • *Average of five smoking imputations among ever-smokers.

  • †Average of five smoking imputations.

  • COPD, chronic obstructive pulmonary disease.