Percentage (%) differences (Cot. − SR) and ratios (Cot./SR) of self-reported (SR) and cotinine-verified (Cot.) smokers relative to study variables in men and women aged ≥20 years in the 2008 Korea National Health and Nutrition Examination Survey
| Study variables | Men | Women | ||||||||
| Number of subjects | SR (%) | Cot. (%) | Cot. − SR (95% CI) | Cot./SR (95% CI) | Number of subjects | SR (%) | Cot. (%) | Cot. − SR (95% CI) | Cot./SR (95% CI) | |
| Total | 2387 | 44.7 | 50.0 | 5.3 (4.3–6.5) | 1.12 (1.10–1.15) | 3068 | 5.9 | 13.9 | 8.0 (6.9–8.8) | 2.36 (2.08–2.61) |
| Age groups (years) | ||||||||||
| 20–29 | 283 | 53.0 | 60.1 | 7.1 (4.2–10.2) | 1.13 (1.07–1.21) | 363 | 11.6 | 23.4 | 11.8 (8.4–15.4) | 2.02 (1.65–2.58) |
| 30–39 | 523 | 55.8 | 60.8 | 5.0 (3.1–7.1) | 1.09 (1.05–1.13) | 608 | 5.6 | 16.8 | 11.2 (8.9–13.7) | 3.00 (2.35–4.12) |
| 40–49 | 505 | 49.7 | 55.3 | 5.6 (3.2–7.9) | 1.11 (1.06–1.17) | 565 | 5.8 | 14.7 | 8.9 (6.5–11.5) | 2.53 (1.96–3.36) |
| 50–59 | 417 | 39.8 | 45.1 | 5.3 (2.6–7.7) | 1.13 (1.07–1.20) | 544 | 3.7 | 10.1 | 6.4 (4.4–8.5) | 2.73 (1.97–4.15) |
| 60 or over | 659 | 31.7 | 36.3 | 4.6 (2.9–6.4) | 1.15 (1.09–1.21) | 988 | 5.3 | 10.2 | 4.9 (3.5–6.5) | 1.92 (1.62–2.42) |
| Education | ||||||||||
| Elementary or less | 477 | 39.6 | 44.4 | 4.8 (2.7–7.1) | 1.12 (1.07–1.19) | 1176 | 6.0 | 11.2 | 5.2 (3.9–6.7) | 1.87 (1.61–2.28) |
| Middle | 321 | 42.7 | 46.7 | 4.0 (1.9–6.5) | 1.09 (1.04–1.16) | 305 | 4.6 | 9.8 | 5.2 (3.0–8.0) | 2.13 (1.55–3.59) |
| High | 858 | 48.0 | 53.7 | 5.7 (4.2–7.3) | 1.12 (1.09–1.16) | 963 | 7.6 | 19.2 | 11.6 (9.5–13.6) | 2.53 (2.11–3.11) |
| College or higher | 731 | 45.1 | 50.8 | 5.7 (3.7–7.7) | 1.13 (1.08–1.18) | 624 | 3.9 | 12.7 | 8.8 (6.6–11.2) | 3.26 (2.45–4.97) |
| Occupation | ||||||||||
| Non-manual | 576 | 45.8 | 52.3 | 6.5 (4.3–8.7) | 1.14 (1.09–1.20) | 375 | 6.9 | 16.8 | 9.9 (6.7–12.8) | 2.43 (1.84–3.44) |
| Manual | 1276 | 47.4 | 52.2 | 4.8 (3.4–6.2) | 1.10 (1.07–1.13) | 1071 | 6.3 | 15.0 | 8.7 (7.0–10.6) | 2.38 (1.99–2.92) |
| Others | 535 | 37.2 | 42.4 | 5.2 (3.4–7.3) | 1.14 (1.09–1.20) | 1622 | 5.4 | 12.5 | 7.1 (5.7–8.4) | 2.31 (1.97–2.76) |
| Current marital status | ||||||||||
| Married with cohabiting | 1877 | 42.5 | 47.7 | 5.2 (4.0–6.3) | 1.12 (1.09–1.15) | 2074 | 4.2 | 12.5 | 8.3 (7.1–9.5) | 2.98 (2.55–3.64) |
| Married without cohabiting | 34 | 52.9 | 55.9 | 3.0 (0.0–11.8) | 1.06 (1.00–1.24) | 49 | 6.1 | 8.2 | 2.1 (0.0–6.1) | 1.34 (1.00–3.00) |
| Never-married | 371 | 53.9 | 59.8 | 5.9 (3.5–8.6) | 1.11 (1.06–1.16) | 300 | 13.0 | 22.7 | 9.7 (6.0–13.7) | 1.75 (1.43–2.22) |
| Divorced or widowed | 105 | 49.5 | 54.3 | 4.8 (1.0–9.5) | 1.10 (1.02–1.21) | 645 | 8.2 | 14.7 | 6.5 (4.6–8.5) | 1.79 (1.52–2.22) |
| Cohabiting with parents | ||||||||||
| Yes | 532 | 49.3 | 55.3 | 6.0 (3.9–8.1) | 1.12 (1.08–1.17) | 509 | 4.7 | 15.5 | 10.8 (8.1–13.6) | 3.30 (2.43–5.15) |
| No | 1855 | 43.5 | 48.5 | 5.0 (3.9–6.2) | 1.11 (1.09–1.15) | 2559 | 6.1 | 13.6 | 7.5 (6.4–8.5) | 2.23 (1.98–2.52) |
| Residential area | ||||||||||
| Seoul | 394 | 43.9 | 48.2 | 4.3 (1.5–7.1) | 1.10 (1.03–1.17) | 515 | 7.8 | 13.4 | 5.6 (3.7–8.0) | 1.72 (1.44–2.20) |
| Other cities | 1375 | 46.1 | 51.6 | 5.5 (4.2–6.8) | 1.12 (1.09–1.15) | 1734 | 6.3 | 15.5 | 9.2 (7.8–10.7) | 2.46 (2.14–2.86) |
| Rural area | 618 | 42.2 | 47.6 | 5.4 (3.6–7.3) | 1.13 (1.08–1.18) | 819 | 3.8 | 10.7 | 6.9 (5.1–8.7) | 2.82 (2.14–3.93) |
| Secondhand smoking exposure | ||||||||||
| None | 1164 | 38 | 42.5 | 4.5 (3.3–6.0) | 1.12 (1.08–1.16) | 1920 | 3.3 | 8.5 | 5.2 (4.2–6.3) | 2.58 (2.17–3.24) |
| <1 h/day | 778 | 44.6 | 49.9 | 5.3 (3.7–6.9) | 1.12 (1.08–1.16) | 605 | 8.4 | 18.8 | 10.4 (8.1–13.1) | 2.24 (1.85–2.82) |
| ≥1 h/day | 393 | 63.4 | 70.7 | 7.3 (4.6–10.2) | 1.12 (1.07–1.17) | 460 | 12.8 | 29.4 | 16.6 (12.7–2.02) | 2.30 (1.88–2.85) |
| Unknown | 52 | 57.7 | 63.5 | 5.8 (0.0–11.5) | 1.10 (1.00–1.25) | 83 | 9.6 | 15.7 | 6.1 (1.2–12.0) | 1.64 (1.13–3.00) |
CI, confidence interval.