Table 1 Characteristics at first follow-up of newly educated female health care workers without previous history of LBP at baseline (n = 2,235)

Physical work demand (Mean, SD^a)

8.60 (2.86)

16.72 (2.19)

29.20 (6.76)

<0.001^*

17.31 (9.55)

17.36 (9.38)

18.81 (9.24)

0.265

Body mass index (Mean, SD^a)

24.66 (4.54)

25.73 (5.51)

24.91 (5.57)

0.022^*

22.08 (1.70)

27.07 (1.39)

34.80 (6.08)

<0.001^*

Age in years (Mean, SD)

36.90 (10.21)

35.58 (10.39)

34.44 (10.54)

0.010^*

34.02 (10.79)

35.98 (10.56)

35.17 (9.76)

0.012^*

Social support at work (Mean, SD^a)

86.29 (9.80)

84.47 (11.13)

81.33 (12.60)

<0.001^*

84.20 (10.84)

83.44 (12.31)

83.79 (13.14)

0.574

Influence at work (Mean, SD^a)

69.07 (20.45)

64.35 (19.87)

58.98 (21.60)

<0.001^*

64.97 (20.34)

61.54 (22.51)

64.21 (22.28)

0.071

Current smokers %

34.4%

32.5%

37.1%

0.237

38.8%

28.7%

32.6%

0.029^*

Workplaces %

Elder care Center

42.5%

41.8%

39.2%

0.411

37.0%

42.1%

37.9%

0.247

Home care

29.7%

33.8%

30.6%

25.7%

28.8%

32.6%

Hospital

6.8%

3.4%

7.1%

6.3%

6.5%

1.5%

Other

21.0%

21.1%

23.1%

31.0%

22.6%

28.0%