Table 1 Demographic characteristics of the subjects in each group recruited from Tehran, Iran during 2012–2013

sex

Male

55 (90.2 %)

56 (90.3 %)

54 (90.0 %)

0.99

Female

6 (9.7 %)

6 (9.7 %)

6 (10.0 %)

Age

47.36 ± 16.30

45.53 ± 16.43

45.05 ± 15.81

0.78

Nation

Iranian

53 (86.9 %)

50 (80.6 %)

54 (90.0 %)

0.32

Afghan

8 (13.1 %)

12 (19.4 %)

6 (10.0 %)

Marital status

Single

24 (39.3 %)

27 (43.5 %)

25 (41.7 %)

0.89

Married

37 (60.7 %)

35 (56.5 %)

35 (58.3 %)

Living area

Urban

38 (62.3 %)

38 (61.3)

43 (71.7 %)

0.32

Rural

23 (37.7 %)

24 (38.7 %)

17 (28.3 %)

Education

Illiterate

10 (16.4 %)

14 (22.6 %)

9 (15.0 %)

0.62

Under diploma

31 (50.8 %)

34 (54.8 %)

35 (58.3 %)

Diploma and academic

20 (32.8 %)

14 (22.6 %)

16 (26.7 %)

Job

Manual

18 (29.5 %)

23 (37.1 %)

29 (48.3 %)

0.10

Office-worker

43 (70.5)

39 (62.9 %)

31 (51.7 %)