Table 1 Characteristics of cases and controls (n = 138)

Age:

   1-24 yrs

11 (15)

4 (6)

1.00

   25-45 yrs

32 (44)

16 (24)

0.73 (0.20-2.65)

   46-65 yrs

25 (35)

32 (49)

0.28 (0.10-1.00)

   >65 yrs

4 (6)

11 (17)

0.13 (0.03-0.70)

   Missing

0 (0)

3 (4)

-

p-trend <0.001

Gender:

   Male

37 (51)

18 (27)

1.00

   Female

35 (49)

48 (73)

0.35 (0.17-0.72)

Child cohabitant:

   No

40 (56)

54 (82)

1.00

   Yes

31 (43)

12 (18)

3.48 (1.60-7.60)

   Missing

1 (1)

0 (0)

-

IMD score:

   Min-14 (least deprived)

6 (8)

2 (3)

1.00

   15-29

18 (25)

15 (23)

0.40 (0.07-2.28)

   30-44

36 (50)

26 (40)

0.46 (0.09-2.47)

   45-max (most deprived)

8 (11)

14 (21)

0.19 (0.03-1.18)

   Missing

4 (6)

9 (14)

-

p-trend = 0.041

Flu Vaccine 08/09:

   No

55 (76)

34 (52)

1.00

   Yes

17 (24)

30 (45)

0.35 (0.17-0.73)

   Missing

0 (0)

2 (3)

-

Smoking status:

   Non-smokers

38 (58)

47 (65)

1.00

   Current smokers

28 (42)

25 (35)

0.72 (0.36-1.44)

Co-morbidity:

   No

56 (78)

41 (62)

1.00

   Yes

16 (22)

25 (38)

0.47 (0.22-0.99)

Frequency of habitual bus/tram use:

   <once a week

40 (56)

24 (36)

1.00

   1-3 times a week

9 (13)

22 (33)

0.27 (0.11-0.69)

   >3 times a week

18 (25)

18 (27)

0.68 (0.29-1.57)

   Missing

5 (7)

2 (3)

-

p-trend = 0.196

Use of bus/tram in previous 5 days:

   No

34 (47)

31 (47)

1.00

   Yes

38 (53)

31 (47)

1.10 (0.55-2.21)

   Missing

0 (0)

4 (6)

-