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, 2, 3, 6, 9, 10, 12) | 0.98 (0.84–1.15) | 27.1 | 77.9 | < 0.001 |
 | Smoking-adjusted | 7 (1, 2, 3, 6, 9, 10, 12) | 0.98 (0.84–1.15) | 27.1 | 77.9 | < 0.001 |
 | Never smokers | 6 (1, 2, 3, 6, 9, 11) | 1.10 (1.02–1.19) | 1.5 | 0.0 | 0.911 |
Any (USA) | Overall data | 5 (1, 2, 3, 6, 12) | 0.95 (0.74–1.22) | 26.5 | 84.9 | < 0.001 |
 | Smoking-adjusted | 5 (1, 2, 3, 6, 12) | 0.95 (0.74–1.22) | 26.5 | 84.9 | < 0.001 |
 | Never smokers | 4 (1, 2, 3, 6) | 1.10 (1.01–1.20) | 1.5 | 0.0 | 0.679 |
Snuff (Scandinavia) | Overall data | 2 (9, 10) | 1.03 (0.91–1.16) | 0.5 | 0.0 | 0.475 |
 | Smoking-adjusted | 2 (9, 10) | 1.03 (0.91–1.16) | 0.5 | 0.0 | 0.475 |
 | Never smokers | 2 (9, 11) | 1.10 (0.94–1.29) | 0.0 | 0.0 | 1.000 |