Table 1 Univariate and multivariate Cox regression analyses of the potential prognostic factors contributing to claim duration in self-employed persons

Age

- ≤ 40 year

70 (25%)

1

-

1

-

- 41-50 year

131 (48%)

0.89

0.47

0.54 (0.36-0.80)

0.002

- > 50 year

74 (27%)

0.96

0.81

0.64 (0.41-0.99)

0.05

Gender

- female

20 (7%)

1

-

1

-

- male

256 (93%)

1.25

0.45

1.59 (0.78-3.21)

0.20

General health

- poor health

36 (13%)

1

-

1

-

- good health

240 (87%)

1.51

0.06

0.90 (0.54-1.49)

0.68

Marital status

- living alone

25 (8%)

1

-

- living together

251 (92%)

0.83

0.42

-

-

Physical Disease-related factorsbody functions

History of similar symptoms -yes

- no

108 (39%)

1

-

1

-

- yes

168 (61%)

1.50

0.004

2.20 (1.52-3.18)

< 0.001

Pain severity prev. 6 months

mean (sd)

5.6 (2.3)

0.94

0.02

0.96 (0.89-1.04)

0.32

Location musculoskeletal symptoms

- no symptoms

56 (21%)

1

-

1

-

- upper extremity

33 (12%)

0.82

0.40

1.16 (0.64-2.10)

0.63

- back

55 (20%)

0.95

0.78

1.04 (0.63-1.72)

0.88

- lower extremity

23 (8%)

0.47

0.01

0.49 (0.23-1.06)

0.07

- multiple locations

106 (39%)

0.58

0.003

0.72 (0.45-1.17)

0.18

Duration of symptoms

- < 2 months

107 (39%)

1

-

1

-

- 2-6 months

90 (33%)

0.65

0.007

0.75 (0.50-1.14)

0.18

- > 6 months

77 (28%)

0.53

< 0.001

0.60 (0.38-0.95)

0.03

Functional status neck pain (NDI)

- little pain

90 (33%)

1

-

1

-

- medium pain

78 (29%)

0.76

0.11

0.72 (0.45-1.16)

0.18

- much pain

103 (38%)

0.67

0.01

0.56 (0.30-1.02)

0.06

Functional status back pain (QBPDS)

- little pain

87 (34%)

1

-

1

-

- medium pain

90 (34%)

0.74

0.08

1.28 (0.81-2.03)

0.29

- much pain

84 (32%)

0.78

0.14

1.42 (0.75-2.69)

0.29

Interaction: NDI * time

-

1.00

0.26

-

-

Interaction: QBPDS * time

-

1.00

0.24

-

-

Treatment by GP or (para)medical specialist

- no

36 (13%)

1

-

- yes

240 (87%)

0.86

0.46

-

-

External Environmental factors

Hired employee since claim--yes

- no

173 (62%)

1

-

- yes

103 (38%)

0.84

0.22

-

-

Financial situation company

- not good

31 (11%)

1

-

- good

245 (89%)

0.83

0.39

-

-

Insured daily compensation (Euro)

- 0-50

56 (21%)

1

-

1

-

- 50-75

97 (36%)

1.37

0.12

1.40 (0.88-2.22)

0.16

- 75-100

90 (33%)

1.52

0.03

1.52 (0.97-2.39)

0.07

- > 100

26 (10%)

1.21

0.49

1.51 (0.80-2.87)

0.21

Deferment period-- > 14 days

- ≤14 days

161 (58%)

1

-

1

-

- > 14 days

115 (42%)

0.70

0.01

0.83 (0.59-1.17)

0.29

Other factorsMental body functions

Fear of movement

- low fear

111 (37%)

1

-

1

-

- high fear

165 (63%)

0.73

0.03

0.94 (0.67-1.33)

0.74

Self-predicted timing RTW

- < 1 month

56 (21%)

1

-

1

-

- > 1 month/never

82 (30%)

0.28

< 0.001

0.24 (0.15-0.38)

< 0.001

- no idea

134 (49%)

0.25

< 0.001

0.23 (0.15-0.34)

< 0.001

Job satisfaction

- not satisfied

38 (13%)

1

-

1

-

- satisfied

238 (87%)

1.42

0.10

1.85 (1.13-3.04)

0.02

Perceived intensity of physical work

range 1-4, higher is heavier

mean: 2.8 (sd 0.76)

0.90

0.23

-

-

Interaction: perceived physical work * time

-

1.00

0.16

-

-

Work pace/quantity (job demands)

- low

79 (29%)

1

-

- medium

98 (37%)

1.31

0.11

-

-

- high

91 (34%)

1.00

0.98

Willingness to participate in a RCT

- yes

180 (65%)

1

-

1

-

- no

96 (35%)

1.59

0.001

1.41 (1.02-1.92)

0.04