Table 3. Stratified Analyses of Pooled Relative Risks of Metabolic Syndrome for Smoker.
| Group | NO. of studies | RR (95% CI) | P for heterogeneity | I 2 (%) | P for meta-regression |
| Gender | 0.02 | ||||
| Male | 10 | 1.34 (1.20–1.50) | 0.02 | 54.9 | |
| Female | 4 | 0.85 (0.60–1.21) | 0.02 | 71.2 | |
| Amount of smoking | 0.07 | ||||
| Heavy (≥20 cigarettes/d) | 3 | 1.42 (1.27–1.59) | 0.02 | 68.9 | |
| Light (<20 cigarettes/d) | 3 | 1.10 (0.90–1.35) | 0.31 | 16.5 | |
| Definitions of metabolic syndrome | 0.45 | ||||
| Strict NCEP III | 3 | 1.11 (1.02–1.21) | 0.44 | 0.00 | |
| Other | 10 | 1.32 (1.09–1.60) | 0.00 | 78.1 | |
| 1 risk factor modified* | 4 | 1.37 (1.22–1.55) | 0.49 | 0.00 | |
| 2 risk factors modified | 4 | 1.36 (1.00–1.84) | 0.02 | 65.5 | |
| >2 risk factors modified | 2 | 1.04 (0.48–2.25) | 0.00 | 95.5 | |
| Mean follow-up time | 0.18 | ||||
| ≥5 years | 7 | 1.16 (0.99–1.35) | 0.00 | 76.8 | |
| <5 years | 6 | 1.44 (1.18–1.75) | 0.05 | 52.1 | |
| Geographical area | 0.77 | ||||
| Asia | 8 | 1.29 (1.01–1.64) | 0.00 | 81.6 | |
| Europe | 4 | 1.21 (1.04–1.41) | 0.07 | 53.9 | |
| North America | 1 | 1.18 (0.97–1.44) | - | - | |
| Study quality | 0.17 | ||||
| High (NOS scores≥7) | 10 | 1.20 (1.04–1.38) | 0.00 | 75.8 | |
| Low (NOS scores<7) | 3 | 1.58 (1.29–1.95) | 0.97 | 0.00 |
*
Modified criteria used to diagnose metabolic syndrome as compared with strict NCEP III definition.