Table 2.
Association between Peer Influence and Use of Electronic Cigarettes in Subgroup Meta-Analyses by Various Factors*
| Factors | No. of study | Summary OR or RR (95% CI) | Heterogeneity, I2 (%) |
|---|---|---|---|
| Ever use of electronic cigarettes | |||
| All | 7 | 1.86 (1.52 - 2.29) | 88.1 |
| Age of participants | |||
| <18 | 4 | 2.16 (1.53 - 3.06) | 77.6 |
| ≥18 | 3 | 1.50 (1.22 - 1.84) | 83 |
| Region | |||
| United States | 7 | 1.86 (1.52 - 2.29) | 88.1 |
| Sample size | |||
| <3000 participants | 5 | 1.51 (1.27 - 1.79) | 55.2 |
| ≥3000 participants | 2 | 2.22 (1.53 - 3.22) | 91.1 |
| Methodological quality of study | |||
| Low | 1 | 3.03 (1.63 - 5.64) | 100 |
| High | 6 | 1.72 (1.35 - 2.18) | 90 |
| Follow-up period | |||
| ≤12 months | 4 | 2.01 (1.42 - 2.86) | 91.6 |
| >12 months | 3 | 1.45 (1.25 - 1.69) | 20.4 |
| Current use of electronic cigarettes | |||
| All | 6 | 1.86 (1.52 - 2.29) | 88.1 |
| Age of participants | |||
| <18 | 3 | 2.43 (1.41 - 4.19) | 83.9 |
| ≥18 | 3 | 1.91 (1.18 - 3.09) | 91.2 |
| Region | |||
| United States | 5 | 2.14 (1.45 - 3.16) | 90.8 |
| Canada | 1 | 2.15 (1.37 - 3.34) | 100 |
| Sample size | |||
| <3000 participants | 2 | 1.77 (1.13 - 2.75) | 36.7 |
| ≥3000 participants | 4 | 2.23 (1.51 - 3.60) | 92.8 |
| Methodological quality of study | |||
| Low | 4 | 2.01 (1.13 - 3.60) | 90.1 |
| High | 2 | 2.41 (2.06 - 2.81) | 0 |
| Follow-up period | |||
| ≤12 months | 5 | 1.89 (1.37 - 2.59) | 85.4 |
| >12 months | 1 | 4.29 (2.89 - 6.38) | 100 |