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. Author manuscript; available in PMC: 2014 Nov 1.
Published in final edited form as: J Med Genet. 2014 Mar 24;51(5):327–333. doi: 10.1136/jmedgenet-2013-102151

Table 1.

Characteristics of study sample by sex

Characteristic Males (n=2591)
N (%)
Females (n=2763)
N (%)
Baseline age, years
  18–34 659 (25.4) 1164 (42.1)
  35–45 898 (34.7) 973 (35.2)
  46–70 1034 (39.9) 626 (22.7)
Baseline smoking status
  Never 754 (29.1) 2565 (92.8)
  Former 366 (14.1) 87 (3.1)
  Current 1471 (56.8) 111 (4.1)
Smoking quantity (among ever smokers)
  Mean CPD ± SD 12.2 ± 8.3 4.4 ± 4.2
  1–5 923 (50.3) 166 (84.3)
  6–9 223 (12.2) 19 (9.6)
  11–20 486 (26.5) 8 (4.1)
  21–30 170 (9.3) 4 (2.0)
  ≥31 32 (1.7) 0 (0)
Age of smoking initiation (among ever smokers)
  Mean age of smoking initiation ± SD 19.1 ± 6.7 21.8 ± 10.3
  ≤18 1014 (55.3) 89 (45.2)
  19–30 731 (39.9) 74 (37.6)
  ≥31 88 (4.8) 34 (17.3)

Abbreviations: cigarettes per day, CPD; standard deviation, SD.