Table 1 Percentage of National Survey of Health and Development cohort members in each smoking trajectory category by smoking characteristics
Smoking characteristicsSmoking trajectories n (%)
Never smoker (n = 950)Predominantly non-smoker (n = 1101)Predominantly smoker (n = 715)Lifelong smoker (n = 621)
Age at initiation (n)
    <16 years (489)N/A164 (22.8)140 (21.3)185 (32.2)
    ⩾16 years (1459)N/A554 (77.2)516 (78.7)389 (67.8)
    Total (1948)N/A718 (100)656 (100)574 (100)
Smoking status at 25 years (n)
    Never (920)813 (100)91 (9.8)16 (2.7)N/A
    Former (742)N/A624 (67.2)118 (19.6)N/A
    Current (1163)N/A213 (23.0)469 (77.8)481 (100)
    Total (2825)813 (100)928 (100)603 (100)481 (100)
Most recent smoking status (n)
    Never (950)950 (100)N/AN/AN/A
    Former (1531)N/A1065 (96.7)466 (65.2)N/A
    Current (906)N/A36 (3.3)249 (34.8)621 (100)
    Total (3387)950 (100)1101 (100)715 (100)621 (100)
Smoking dosage: average number of cigarettes per day (n)
    1–14 (1305)N/A557 (99.8)587 (82.7)161 (25.9)
    15+ (584)N/A1 (0.2)123 (17.3)460 (74.1)
    Total (2839)N/A558 (100)710 (100)621 (100)
  • N/A, not applicable.