Table 1 Associations between smoking status and inflammatory bowel disease

Never smoking

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Ever smoking

1.51 (1.37, 1.65)

<2 × 10⁻¹⁶

1.49 (1.31, 1.69)

5.83 × 10⁻¹⁰

1.45 (1.34, 1.56)

<2 × 10⁻¹⁶

1.51 (1.37, 1.66)

<2 × 10⁻¹⁶

Previous smoking

1.39 (1.25, 1.54)

5.06 × 10⁻¹⁰

1.41 (1.23, 1.61)

7.00 × 10⁻⁷

1.54 (1.42, 1.66)

<2 × 10⁻¹⁶

1.59 (1.44, 1.76)

<2 × 10⁻¹⁶

Current smoking

1.88 (1.64, 2.16)

<2 × 10⁻¹⁶

1.81 (1.50, 2.19)

7.09 × 10⁻¹⁰

1.15 (1.01, 1.30)

0.038

1.18 (1.00, 1.39)

0.051

<= 20

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20 − 40

1.05 (0.88, 1.25)

0.623

1.10 (0.88, 1.38)

0.393

1.12 (0.98, 1.29)

0.107

1.09 (0.92, 1.29)

0.313

40 − 60

1.22 (0.98, 1.51)

0.070

1.34 (1.02, 1.75)

0.036

1.08 (0.91, 1.29)

0.396

1.08 (0.87, 1.33)

0.485

 > 60

1.03 (0.81, 1.32)

0.805

1.15 (0.85, 1.55)

0.372

1.12 (0.93, 1.35)

0.235

1.05 (0.83, 1.31)

0.703

<= 30

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30 − 40

1.24 (0.98, 1.58)

0.079

1.35 (1.00, 1.81)

0.046

1.18 (0.99, 1.40)

0.069

1.14 (0.93, 1.41)

0.214

40 − 50

1.17 (0.90, 1.52)

0.232

1.26 (0.90, 1.75)

0.178

1.32 (1.10, 1.58)

2.72 × 10⁻³

1.40 (1.12, 1.75)

0.003

 > 50

1.89 (1.46, 2.43)

9.49 × 10⁻⁷

1.79 (1.29, 2.50)

0.001

1.50 (1.24, 1.81)

2.59 × 10⁻⁵

1.48 (1.16, 1.87)

0.001