Table 6 Effect estimates for never smokersa
From: Meta-analysis of the relation between European and American smokeless tobacco and oral cancer
Study | First author, year of publication | Adjustment factors | Exposure | Sex | Exposed cases | OR/RR (95%CI) |
|---|---|---|---|---|---|---|
Studies providing result specific for oral cancer | ||||||
8 | Keller 1970 [75] | None | Smokeless | M | 4 | 3.04 (0.62–14.99) |
16 | Blot 1988 [100] | Age, race, location, respondent | Smokeless | F | 6 | 6.20 (1.90–19.80) |
19 | Blomqvist 1991 [103] | None | Snuff | M+F | 2 | 0.67 (0.08–5.75) |
25 | Kabat 1994 [59] | None | Smokeless | M | 4 | 1.59 (0.51–4.96) |
|  |  |  |  | F | 4 | 38.7 (2.1–723.6)b |
29 | Schildt 1998 [73] | Age, sex, residence | Snuff | M+F | 19 | 0.70 (0.40–1.20) |
32 | Henley 2005 [66] | Age, race, education, alcohol, exercise, aspirin, body mass index, diet, occupationc | Smokeless | M (CPS-I) | 4 | 2.02 (0.53–7.74) |
|  |  |  |  | M (CPS-II) | 1 | 0.90 (0.12–6.71) |
|  |  | Fixed-effect meta-analysis estimate for six studies | 1.30 (0.87–1.93) | |||
|  |  | Random-effects meta-analysis estimate for six studies | 1.94 (0.88–4.28) | |||
|  |  | Heterogeneity | χ2 (df) | 18.99 (7) | ||
| Â | Â | Â | p | 0.0082 | ||
| Â | Â | Â | I2 | 63.13 | ||
Additional study providing result for oral, larynx and oesophagus cancer combined | ||||||
27 | Lewin 1998 [64] | Age, region | Snuff | M | 9 | 4.70 (1.60–13.80) |
|  |  | Fixed-effect meta-analysis estimate for all seven studies | 1.51 (1.04–2.19) | |||
|  |  | Random-effect meta-analysis estimate for all seven studies | 2.20 (1.04–4.67) | |||
|  |  | Heterogeneity | χ2 (df) | 23.82 (8) | ||
| Â | Â | Â | p | 0.0025 | ||
| Â | Â | Â | I2 | 66.42 | ||