Table 2.
Adjusted odds ratios (ORs) and 95% confidence intervals (CIs) of metabolic syndrome associated with cigarette smoking
| Cigarette smoking variables | Discovery stage: TNCHS studya | Replication stage: CHNS studyb | ||||
|---|---|---|---|---|---|---|
| MetS ( +)/All | OR (95%Cl) | P trend c | MetS ( +)/All | OR (95%Cl) | P trend c | |
| Non-smoker | 3,063/13,739 | Reference | 1,047/5,977 | Reference | – | |
| Smoking status | - | – | ||||
| Ever-smoker | 483/1,483 | 1.62 (1.43–1.84) | 512/2588 | 1.18 (0.10–1.40) | ||
| Former | 28/90 | 1.11 (0.68–1.80) | 46/187 | 0.85 (0.57–1.27) | ||
| Current | 455/1,393 | 1.66 (1.46–1.89) | 466/2401 | 1.22 (1.03–1.45) | ||
| Intensity of smoking (cig/day)d | < 0.001 | 0.015 | ||||
| 1–9 | 90/357 | 1.10 (0.85–1.43) | 81/427 | 1.05 (0.77–1.42) | ||
| 10–19 | 186/535 | 1.73 (1.42–2.11) | 131/709 | 1.09 (0.85–1.40) | ||
| 20- | 207/591 | 1.91 (1.58–2.31) | 300/1,452 | 1.27 (1.05–1.54) | ||
| Smoking durationd | < 0.001 | 0.881 | ||||
| Tertile 1 | 143/471 | 1.46 (1.17–1.82) | 156/846 | 1.51 (1.18–1.93) | ||
| Tertile 2 | 154/468 | 1.72 (1.39–2.14) | 197/882 | 1.41 (1.13–1.76) | ||
| Tertile 3 | 186/544 | 1.68 (1.38–2.05) | 159/860 | 0.81 (0.64–1.03) | ||
| Pack-yearsd | < 0.001 | 0.639 | ||||
| Tertile 1 | 132/494 | 1.18 (0.94–1.46) | 160/869 | 1.25 (0.99–1.58) | ||
| Tertile 2 | 172/494 | 1.81 (1.47–2.22) | 172/830 | 1.30 (1.04–1.64) | ||
| Tertile 3 | 179/495 | 1.97 (1.61–2.42) | 180/889 | 1.03 (0.82–1.29) | ||
| CSI categoriesd | < 0.001 | 0.364 | ||||
| Tertile 1 | 132/494 | 1.19 (0.95–1.48) | 161/862 | 1.30 (1.03–1.65) | ||
| Tertile 2 | 168/502 | 1.76 (1.44–2.16) | 181/869 | 1.30 (1.04–1.63) | ||
| Tertile 3 | 183/487 | 2.01 (1.64–2.47) | 170/857 | 0.99 (0.78–1.24) | ||
CSI comprehensive smoking index, OR odds ratio, CI confidence interval
aAdjusted for age, physical activity, body mass index, dietary habits
bAdjusted for sex, age, body mass index, province, and region
cLinear trend was tested by entering the median value of each group of cigarette smoking variables as continuous variables in the models
dParticipants were divided into four groups: non-smokers; and the tertiles of CSI in ever smokers. In the TNCHS: the tertile cut-off points were: 39 and 45 for years of smoking, 19 and 36.5 for pack-years, and 1.550 and 1.940 for CSI. In the CHNS: the tertiles cut-off points were: 23 and 35 years for years smoking, 15 and 30 for pack-years, and 1.171 and 1.701 for CSI