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Table 1 Basic characteristics of the study participants

From: Cost-effectiveness of providing patients with information on managing mild low-back symptoms in an occupational health setting

Characteristics

Combined (n = 89)

Booklet (n = 92)

NC (n = 83)

p

%

mean

SD

%

mean

SD

%

mean

SD

Demographics

          

 Age (years)

.

44

8

.

43

7

.

45

8

0.52

 Male

79

.

.

66

.

.

76

.

.

0.55

 Smoking

30

.

.

28

.

.

31

.

.

0.35

 High school diploma/vocational degree

79

.

.

75

.

.

76

.

.

0.87

General health

          

 Duration of LBP, years

.

12

9

.

11

7

.

14

9

0.09

 SA days before baselinea

    

9

12

 

14

19

0.10

Work-related features

          

 Blue collar worker

69

.

.

64

.

.

78

.

.

0.05

 Shift worker (two or three shift work)

41

.

.

37

.

.

40

.

.

0.73

 Physical workload (1–5)b

.

3

1

.

3

1

.

3

1

0.13

 Mental workload (1–5)b

.

3

1

.

3

1

.

3

1

0.51

 Work ability (0–10)c

.

8.1

1.5

.

8.3

1.5

.

7.8

1.6

0.07

Outcome variables at baseline

          

 Physical impairment (PHI); RM-18 (0–18)d,e

.

4.2

4.6

.

2.5

3.2

.

3.9

3.6

0.34

 Low back pain (LBP); VAS (0–100)d, mm

.

20

7

.

20

7

.

19

7

0.52

Other LB specific variables

          

 Fear Avoidance Beliefs Questionnaire (13–78)d

.

29

10

.

29

11

.

31

11

0.15

  1. aall cause sickness absence days during 12 months prior to baseline (register data)
  2. b1–5 indicates self-rated load: 1 = very heavy, 2 = moderate, 3 = intermediate, 4 = rather light, 5 = very light
  3. crange 0–10, when 0 is lowest possible work ability and 10 is best possible work ability
  4. dHigher value indicates higher impairment, pain or fear of pain, respectively
  5. efor the comparison between Booklet and NC, mean difference of PHI is significant (p = 0.01)
  6. Means (SD = standard deviation) or percentages when applicable. Intervention groups were pooled for the comparison between the intervention and NC. [Combined = Back Book and Advice intervention group; Booklet = Back Book intervention group; NC Natural Course control group; BMI Body mass Index; SA sickness absence; LBP low back pain; VAS Visual Analogue Scale; RM-18 Roland-Morris 18-item Disability Questionnaire; PHI Physical impairment;; p = P-value]. Missing values (concerning smoking, duration of LBP and shift work) were imputed with the multiple imputation procedure