From: Systematic review of the relation between smokeless tobacco and cancer in Europe and North America
 |  |  |  | Heterogeneity | ||
---|---|---|---|---|---|---|
Type of ST (region)a | Adjustments/restrictionsb | Number of estimates (RR/OR ids)c | Random-effects RR/OR (95% CI) | χ2 | I2 | P(χ2) |
Any | Overall data | 7 (1, 5, 7, 11, 17, 18, 23) | 1.00 (0.68–1.47) | 18.5 | 67.5 | 0.005 |
 | Smoking-adjusted | 7 (1, 5, 7, 11, 16, 18, 23) | 1.07 (0.71–1.60) | 21.2 | 71.7 | 0.002 |
 | Never smokers | 5 (6, 10, 16, 18, 24) | 1.23 (0.66–2.31) | 10.7 | 62.7 | 0.030 |
Any (USA) | Overall data | 5 (1, 11, 17, 18, 23) | 0.86 (0.47–1.57) | 10.2 | 61.0 | 0.037 |
 | Smoking-adjusted | 5 (1, 11, 16, 18, 23) | 0.99 (0.51–1.91) | 13.8 | 71.0 | 0.008 |
 | Never smokers | 3 (16, 18, 24) | 1.09 (0.44–2.67) | 5.4 | 63.0 | 0.067 |
Snuff (Scandinavia) | Overall data | 2 (5, 7) | 1.20 (0.66–2.20) | 6.3 | 84.1 | 0.012 |
 | Smoking-adjusted | 2 (5, 7) | 1.20 (0.66–2.20) | 6.3 | 84.1 | 0.012 |
 | Never smokers | 2 (6, 10) | 1.61 (0.77–3.34) | 1.5 | 33.2 | 0.221 |