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Table 4 Tobacco smoking, coffee and alcohol intake, body mass index, physical activity, and pets and risk of rheumatoid arthritis, Denmark 1998 to 2003

From: Environmental risk factors differ between rheumatoid arthritis with and without auto-antibodies against cyclic citrullinated peptides

 

Women

Men

Both genders

 

Number of patients/controls

ORa (95% CI)

Number of patients/controls

ORa (95% CI)

ORa (95% CI)

Smoker status

     

   Never

128/223

1 (ref)

26/75

1 (ref)

1 (ref)

   Former

68/76

1.69 (1.12 to 2.55)

40/79

1.58 (0.84 to 2.97)

1.57 (1.13 to 2.19)

   Current

170/179

1.84 (1.33 to 2.54)

83/137

1.89 (1.09 to 3.30)

1.80 (1.37 to 2.36)

   Test for homogeneity (p)

 

<0.001

 

0.08

< 0.001

Pack-years smoked b

     

   0 pack-years

128/223

1 (ref)

26/75

1 (ref)

1 (ref)

   >0 to 10 pack-years

77/100

1.54 (1.04 to 2.28)

21/42

1.42 (0.69 to 2.91)

1.44 (1.02 to 2.02)

   >10 to 20 pack-years

78/81

1.84 (1.23 to 2.77)

25/44

1.86 (0.92 to 3.77)

1.84 (1.30 to 2.59)

   >20 pack-years

78/70

2.07 (1.35 to 3.16)

76/126

2.00 (1.12 to 3.58)

1.93 (1.40 to 2.68)

   Trend test (p)

 

<0.001

 

0.03

<0.001

Coffee consumption c

     

   0 cups per day

70/116

1 (ref)

14/26

1 (ref)

1 (ref)

   >0 to 5 cups per day

148/219

1.16 (0.76 to 1.79)

42/107

0.79 (0.35 to 1.81)

1.12 (0.77 to 1.64)

   >5 to 10 cups per day

117/122

1.68 (1.05 to 2.70)

60/112

1.09 (0.49 to 2.46)

1.59 (1.07 to 2.38)

   >10 cups per day

30/20

2.88 (1.43 to 5.79)

33/45

1.57 (0.64 to 3.84)

2.33 (1.40 to 3.87)

   Trend test (p)

 

<0.001

 

0.05

<0.001

Alcohol consumption c,d

     

   0 drinks per week

79/80

1.36 (0.91 to 2.03)

11/13

1.38 (0.51 to 3.72)

1.34 (0.93 to 1.93)

   >0 to 5 drinks per week

170/227

1 (ref)

42/75

1 (ref)

1 (ref)

   >5 to 10 drinks per week

68/109

0.87 (0.60 to 1.27)

35/54

1.24 (0.68 to 2.26)

0.95 (0.70 to 1.30)

   >10 to 15 drinks per week

29/34

1.21 (0.69 to 2.11)

11/41

0.42 (0.19 to 0.94)

0.80 (0.52 to 1.24)

   >15 drinks per week

15/26

0.74 (0.37 to 1.47)

47/104

0.82 (0.47 to 1.43)

0.79 (0.53 to 1.17)

   Trend test (p)

 

0.21

 

0.20

0.05

Wine consumption c

     

   0 glasses per week

120/135

1.23 (0.89 to 1.71)

36/65

0.89 (0.52 to 1.52)

1.09 (0.83 to 1.44)

   >0 to 5 glasses per week

191/251

1 (ref)

87/139

1 (ref)

1 (ref)

   >5 to 10 glasses per week

34/67

0.62 (0.39 to 1.00)

18/57

0.48 (0.26 to 0.89)

0.57 (0.39 to 0.83)

   >10 to 15 glasses per week

11/16

0.82 (0.36 to 1.86)

2/17

0.15 (0.03 to 0.70)

0.53 (0.27 to 1.04)

   >15 glasses per week

6/8

0.96 (0.31 to 2.92)

6/11

1.05 (0.35 to 3.09)

0.95 (0.44 to 2.02)

   Trend test (p)

 

0.10

 

0.08

0.02

Body mass index c

     

   <18.5 kg/m2 (underweight)

25/36

0.95 (0.52 to 1.73)

3/5

0.95 (0.19 to 4.72)

0.90 (0.52 to 1.56)

   18.5 to < 25 kg/m2 (normal weight)

232/327

1 (ref)

73/137

1 (ref)

1 (ref)

   25 to < 30 kg/m2 (overweight)

73/80

1.26 (0.87 to 1.85)

52/116

0.86 (0.54 to 1.37)

1.05 (0.79 to 1.40)

   ≥ 30 kg/m2 (obese)

26/21

1.83 (0.97 to 3.44)

21/30

1.39 (0.71 to 2.71)

1.57 (1.01 to 2.44)

   Trend test (p)

 

0.04

 

0.57

0.07

Body mass index at age 20

     

   <18.5 kg/m2 (underweight)

56/62

1.39 (0.92 to 2.10)

4/9

0.75 (0.21 to 2.73)

1.29 (0.88 to 1.89)

   18.5 to <25 kg/m2 (normal weight)

258/371

1 (ref)

108/220

1 (ref)

1 (ref)

   25 to <30 kg/m2 (overweight)

36/30

1.72 (1.01 to 2.92)

28/38

1.65 (0.93 to 2.93)

1.61 (1.10 to 2.34)

   ≥ 30 kg/m2 (obese)

4/6

1.33 (0.35 to 5.09)

5/5

1.92 (0.50 to 7.38)

1.59 (0.63 to 4.00)

   Trend test (p)

 

0.64

 

0.05

0.15

Physical activity at work c

     

   Not physically demanding

46/94

1 (ref)

23/59

1 (ref)

1 (ref)

   Slightly physically demanding

80/104

1.53 (0.95 to 2.47)

37/73

1.25 (0.65 to 2.41)

1.47 (1.01 to 2.14)

   Moderately physically demanding

91/106

1.70 (1.07 to 2.72)

47/85

1.41 (0.75 to 2.67)

1.64 (1.13 to 2.37)

   Very physically demanding

85/94

1.84 (1.14 to 2.96)

35/58

1.62 (0.82 to 3.18)

1.73 (1.18 to 2.53)

   Unemployed

63/80

1.68 (0.95 to 2.98)

7/16

0.94 (0.30 to 2.93)

1.48 (0.91 to 2.42)

   Trend test (p)e,f

 

0.01

 

0.11

0.005

Physical activity in leisure time c

     

   Not physically demanding

28/28

1 (ref)

25/29

1 (ref)

1 (ref)

   Slightly physically demanding

125/150

0.80 (0.44 to 1.45)

52/76

0.84 (0.42 to 1.66)

0.77 (0.50 to 1.19)

   Moderately physically demanding

180/260

0.65 (0.37 to 1.16)

59/145

0.44 (0.23 to 0.84)

0.56 (0.37 to 0.86)

   Very physically demanding

33/39

0.92 (0.44 to 1.94)

13/41

0.26 (0.10 to 0.65)

0.61 (0.35 to 1.05)

   Trend test (p)e

 

0.35

 

<0.001

0.004

Pets as adult

     

   Never

68/51

1 (ref)

22/36

1 (ref)

1 (ref)

   Ever

298/427

0.46 (0.30 to 0.71)

127/255

0.85 (0.46 to 1.58)

0.56 (0.40 to 0.79)

   Test for homogeneity (p)

 

<0.001

 

0.61

<0.001

  1. Due to missing values for some individuals, numbers do not always add up to 366 female and 149 male patients with RA and 478 female and 291 male controls. aAdjusted for birth year, year or pseudo-year of RA diagnosis, and (when combined) gender. bOne pack-year is equivalent to 7,300 cigarettes (20 cigarettes per day for 1 year). cTen years prior to interview. dOne drink is equivalent to one bottle of normal beer, 0.67 bottle of strong beer, or one glass of wine, dessert wine, or spirits. eTrend tests on the original categories, which were enumerated by consecutive numbers starting with one. fIncluding only individuals who had a job. CI, confidence interval; OR, odds ratio; ref, reference.