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 | 9 (2, 3, 6, 11, 13, 19, 20, 21, 24) | 0.96 (0.73–1.27) | 53.2 | 85.0 | < 0.001 |
 | Smoking-adjusted | 6 (2, 3, 6, 11, 13, 20) | 0.99 (0.71–1.37)d | 28.7 | 82.6 | < 0.001 |
 | Never smokers | 5 (2, 3, 6, 12, 16) | 1.34 (0.80–2.23) | 11.5 | 65.3 | 0.021 |
Any (USA) | Overall data | 6 (2, 3, 6, 20, 21, 24) | 1.22 (0.82–1.83) | 18.5 | 73.0 | 0.002 |
 | Smoking-adjusted | 4 (2, 3, 6, 20) | 1.38 (0.72–2.64) | 16.5 | 81.9 | 0.001 |
 | Never smokers | 3 (2, 3, 6) | 1.79 (0.91–3.51) | 6.2 | 67.8 | 0.045 |
Snuff (Scandinavia) | Overall data | 2 (11, 13) | 0.71 (0.66–0.76) | 0.9 | 0.0 | 0.354 |
 | Smoking-adjusted | 2 (11, 13) | 0.71 (0.66–0.76) | 0.9 | 0.0 | 0.354 |
 | Never smokers | 2 (12, 16) | 0.82 (0.52–1.28) | 0.1 | 0.0 | 0.798 |