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 (1, 6, 9, 10, 14, 15, 17, 19, 21) | 1.03 (0.90–1.19) | 10.5 | 24.0 | 0.230 |
 | Smoking-adjusted | 8 (1, 6, 9, 10, 14, 17, 19, 21) | 1.03 (0.88–1.20) | 10.3 | 31.9 | 0.173 |
 | Never smokers | 4 (2, 6, 11, 20) | 1.27 (0.75–2.13) | 7.0 | 57.2 | 0.072 |
Any (USA) | Overall data | 4 (1, 6, 14, 15) | 1.41 (0.95–2.10) | 0.1 | 0.0 | 0.988 |
 | Smoking-adjusted | 3 (1, 6, 14) | 1.41 (0.93–2.12) | 0.1 | 0.0 | 0.942 |
 | Never smokers | 2 (2, 6) | 1.96 (0.82–4.70) | 1.6 | 38.2 | 0.203 |
Snuff (Scandinavia) | Overall data | 5 (9, 10, 17, 19, 21) | 0.98 (0.82–1.17) | 8.1 | 50.4 | 0.089 |
 | Smoking-adjusted | 5 (9, 10, 17, 19, 21) | 0.98 (0.82–1.17) | 8.1 | 50.4 | 0.089 |
 | Never smokers | 2 (11, 20) | 0.90 (0.35–2.30) | 4.2 | 76.4 | 0.040 |