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Table 4 Oropharyngeal cancer; meta-analysis results

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

n = 41 (1, 2, 3, 6, 7, 11, 15, 16, 18, 19, 20, 21, 22, 23, 24,

25, 26, 28, 29, 30, 33, 34, 35, 38, 39, 41, 42, 46, 47, 48, 49, 51,

55, 56, 58, 60, 63, 65, 73, 74, 77)

1.79 (1.36–2.36)

335.6

88.1

< 0.001

 

Smoking-adjusted

n = 19 (2, 3, 6, 7, 11, 13, 18, 26, 35, 43, 48, 51, 55, 56, 58, 63, 69, 74, 77)

1.36 (1.04–1.77)

69.5

74.1

< 0.001

 

Smoking and

alcohol adjusted

n = 10 (2, 3, 11, 51, 55, 56, 63, 69, 74, 77)

1.07 (0.84–1.37)

12.5

28.0

0.186

 

Never smokers

n = 9 (2, 3, 10, 12, 27, 43, 48, 59, 72)

1.72 (1.01–2.94)

15.9

49.7

0.044

 

Never smokers

– alcohol adjusted

n = 3 (2, 3, 12)

1.87 (0.82–4.27)

0.6

0.0

0.731

Any (USA)d

Overall data

n = 31 (1, 2, 3, 15, 16, 18, 19, 20, 21, 22, 23, 24, 25, 26, 29, 30,

33, 34, 35, 38, 39, 41, 42, 46, 49, 51, 55, 56, 58, 65, 74)

2.16 (1.55–3.02)

275.8

89.1

< 0.001

 

Smoking-adjusted

n = 12 (2, 3, 13, 18, 26, 35, 43, 51, 55, 56, 58, 74)

1.65 (1.22–2.25)

33.6

67.3

< 0.001

 

Smoking and

alcohol adjusted

n = 6 (2, 3, 51, 55, 56, 74)

1.04 (0.80–1.35)

1.8

0.0

0.875

 

Never smokers

n = 5 (2, 3, 27, 43, 59)

3.33 (1.76–6.32)

3.5

0.0

0.476

 

Never smokers –

alcohol adjusted

n = 2 (2, 3)

1.58 (0.52–4.81)

0.4

0.0

0.512

Snuff

(Scandinavia)

Overall data

n = 7 (6, 7, 11, 48, 63, 69, 77)

0.97 (0.68–1.37)

14.5

58.8

0.024

 

Smoking-adjusted

n = 7 (6, 7, 11, 48, 63, 69, 77)

0.97 (0.68–1.37)

14.5

58.8

0.024

 

Smoking and

alcohol adjusted

n = 4 (11, 63, 69, 77)

1.10 (0.64–1.90)

10.7

71.9

0.014

 

Never smokers

n = 4 (10, 12, 48, 72)

1.01 (0.71–1.45)

2.2

0.0

0.524

 

Never smokers –

alcohol adjusted

n = 1 (12)

2.30 (0.67–7.92)

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Published since 1990

Overall data

n = 18 (1, 2, 3, 6, 7, 11, 48, 49, 51, 55, 56, 58, 60, 63, 65, 73, 74, 77)

1.28 (0.94–1.76)

81.7

79.2

< 0.001

 

Smoking-adjusted

n = 14 (2, 3, 6, 7, 11, 48, 51, 55, 56, 58, 63, 69, 74, 77)

1.00 (0.83–1.20)

18.5

29.8

0.139

 

Smoking and

alcohol adjusted

n = 10 (2, 3, 11, 51, 55, 56, 63, 69, 74, 77)

1.07 (0.84–1.37)

12.5

28.0

0.186

 

Never smokers

n = 7 (2, 3, 10, 12, 48, 59, 72)

1.24 (0.80–1.90)

7.5

20.1

0.277

 

Never smokers –

alcohol adjusted

n = 3 (2, 3, 12)

1.87 (0.82–4.27)

0.6

0.0

0.731

  1. a For each study/sex, the RR/OR for ST from Table 3 was included if available, otherwise that for chewing tobacco or snuff was used.
  2. b Smoking-adjusted includes estimates for smokers and non-smokers combined, adjusted for smoking if available, and estimates for never smokers otherwise.
  3. c The actual estimates included are identified by their RR/OR identification numbers as given in Table 3.
  4. d Includes estimates 24 and 25 from a study in Puerto Rico [49].
  5. CI = confidence interval; ST = smokeless tobacco; OR = odds ratio; RR = relative risk.
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