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Table 1 Selected socio-demographic characteristics of male subjects in the two case–control studies, Montreal, Canada

From: Occupational exposure to wood dust and risk of lung cancer in two population-based case–control studies in Montreal, Canada

   Study I (1979–1986) Study II (1996–2001)
Variables Categories Population controls Cancer controls Cancer cases Population controls Cancer cases
N = 533 N = 1349 N = 857 N = 894 N = 736
Age group (%) ≤55 years 28.0 32.5 27.4 11.9 13.6
  56-65 years 45.2 43.7 50.8 28.6 32.9
  66-75 years 26.8 23.7 21.8 59.5 53.5
Ethnolinguistic group (%) French 64.2 58.0 69.1 64.4 77.4
English 14.1 16.1 13.5 6.4 4.6
  Other 21.8 25.9 17.4 29.2 17.9
Schooling (%) <7 years 20.3 22.3 30.3 24.7 28.0
  7-12 years 56.1 55.2 57.1 48.1 56.2
  ≥13 years 23.6 22.5 12.6 27.2 15.8
Median family income* 100 93 84 100 94
Smoking (%) Never 19.7 17.3 1.5 17.7 2.4
  Current 46.9 58.0 79.9 29.2 67.5
Quit smoking (%) 2-5 years ago 8.8 6.7 7.6 2.8 4.3
  5-10 years ago 7.9 6.2 6.0 6.6 5.8
  >10 years ago 16.7 11.8 5.0 43.7 19.8
Mean pack-years** 49,9 52.3 74.3 50.3 78.5
Respondent (%) Self 87.4 80.8 70.6 90.3 60.2
  Proxy 12.6 19.2 29.4 9.7 39.8
  1. *Indicator of inter-subject mean of the median family income for census tract of residence, using the study-specific mean value among population controls as the reference value for each study (x 100). Based on the 1981 census for Study I and the 1991 census for Study II.
  2. **Among ever smokers, based on 20 cigarettes per packet.