Table 2. Subgroup Analysis of Cigarette Smoking Initiation.
| Studies Included in Analysis | No. of Studies | No. of Respondents | Pooled Adjusted OR (95% CI) | I2, % | P Value for Test of Heterogeneity |
|---|---|---|---|---|---|
| All | 7 | 8936 | 3.50 (2.38-5.16) | 56 | .03 |
| Mean age of sample at baseline, y | |||||
| <18 | 3 | 4765 | 3.03 (1.65-5.55) | 80 | .01 |
| ≥18 | 4 | 4171 | 4.11 (2.63-6.41) | 0 | .67 |
| Baseline year of study | |||||
| <2014 | 4 | 6076 | 2.77 (1.67-4.60) | 52 | .10 |
| ≥2014 | 3 | 2860 | 4.48 (3.06-6.57) | 0 | .37 |
| Sample | |||||
| Regional | 4 | 5011 | 3.08 (1.96-4.84) | 71 | .02 |
| National | 3 | 3925 | 5.64 (2.76-11.54) | 0 | .84 |
Abbreviation: OR, odds ratio.