Table 4 Tobacco chewing and oral cancer among women—former tobacco chewers are excluded from analysis

From: Tobacco chewing and female oral cavity cancer risk in Karunagappally cohort, India

Times

Oral cancer cases

Person-years

RR

95% CI

 

Daily frequency

 Never

25

706 872

1

Reference

 

 1–4

16

95 614

3.3

1.7–6.4

 

 5–9

25

62 143

7.8

4.4–13.9

 

 10+

12

25 063

9.2

4.5–18.7

 

 Unknown

0

4558

  

P for trenda <0.001

Starting age (years)

     

 <20

4

21 989

3.8

1.9–7.5

 

 20−

15

46 775

7.8

4.2–14.4

 

 30−

18

49 953

6.4

3.3– 12.4

 

 40+

14

60 799

3.5

1.2–10.1

 

 Never

25

706 872

1

Reference

 

 Unknown

2

7862

5.7

1.3–24.3

 
     

P for trendb >0.5

  1. Relative risk (RR) and 95% confidence interval (CI) were obtained from the following model: H=Hs exp(BiXi), where background hazard, Hs, was stratified by attained age (5-year category) and family income; and Xi are categorical variables for tobacco chewing.
  2. aThe category of ‘unknown’ was excluded when calculating P for trend.
  3. bThe categories of never-tobacco chewers and unknown were excluded when calculating P-value.
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