Table 2

Results from the multivariable analyses of recovery from WADa, c-index and internally validated c-index (n=680)
Prognostic factors Model 1a(n=679)b Model 2a(n=648)b Final model 3a(n=633)b
β (SE) β (SE) β (SE) HRR (95% CI) p-value
Age -0.01 (0.00) -0.01 (0.00) -0.01 (0.00) 0.99 (0.98, 1.00)* 0.002
Education
< Grade 8** 0.0 0.0 - - -
Grade 8 0.21 (0.28) 0.23 (0.28) - - -
High school 0.51 (0.27) 0.48 (0.27) - - -
Post-secondary school 0.28 (0.27) 0.29 (0.27) - - -
Technical school 0.41 (0.28) 0.31 (0.28) - - -
University 0.69 (0.28) 0.59 (0.28) - - -
No. of days to reporting the collision -0.02 (0.01) -0.02 (0.01) 0.98 (0.97, 0.99) ≤0.001
Neck pain intensityc
Mild** 0.0 0.0 1.0
Moderate -0.48 (0.14) -0.43 (0.14) 0.65 (0.50, 0.85) 0.002
Severe -0.70 (0.15) -0.50 (0.15) 0.61 (0.45, 0.82) 0.001
Low back pain intensityc
No pain** 0.0 0.0 1.0
Mild -0.01 (0.16) 0.17 (0.15) 1.19 (0.88, 1.61) 0.26
Moderate -0.29 (0.12) -0.16 (0.12) 0.85 (0.68, 1.07) 0.17
Severe -0.46 (0.15) -0.41 (0.15) 0.66 (0.49, 0.89) 0.01
Pain other than neck and back pain
No** 0.0 0.0 1.0
Yes -0.38 (0.11) -0.35 (0.11) 0.71 (0.57, 0.88) 0.002
Musculoskeletal problem before collisiond
Absent** 0.0 - - -
No/Mild -0.03 (0.12) - - -
Severe -0.33 (0.18) - - -
Headache before collision
Absent** 0.0 0.0 1.0
No/Mild 0.32 (0.11) 0.28 (0.11) 1.32 (1.07, 1.63) 0.01
Severe -0.01 (0.15) -0.03 (0.15) 0.97 (0.72, 1.31) 0.87
MD visits since collisione
1** 0.0 - - -
2 -0.05 (0.11) - - -
≥ 3 -0.26 (0.13) - - -
Recovery expectationsf
Better soon** 0.0 1.0
Better slowly/Never better -0.66 (0.12) 0.51 (0.41, 0.65) ≤0.001
Don′t know -1.09 (0.14) 0.34 (0.26, 0.44) ≤0.001
C-index (95% CI) 0.56 (0.53, 0.59) 0.65 (0.63, 0.68) 0.68 (0.65, 0.71)
Internal validated c-index (95% CI) 0.55 (0.51, 0.58) 0.63 (0.59, 0.66) 0.67 (0.63, 0.70)

Note: Overall Goodness of fit for the final model was adequate according to the Cox-Snell residual plot and the score test (p= 0.66).

* 95% CI: 0.984, 0.996.

** Reference category.

a Cox proportional hazard regression: Model 1: Result from including socio-demographics related factors in the backward selection process. Model 2: Result using prognostic factors remaining from model 1 plus factors related to collision, symptoms, comorbidity and health care. Final model 3: Result using prognostic factors remaining from model 2 plus factors related to general health and psychology.

b Numbers of subjects are less than the study population (n=680) due to missing answer for prognostic factors in the backward selection procedures.

c 11 point numeric rating scale (NRS) were 0 = no pain at all and 10 = pain as bad as it could be. Mild: 1-4, Moderate: 5-7, Severe: 8-10.

d The effect on health from muscle, bone or joint problems within 6 months before the collision.

e MD: Medical doctor.

f The answer to the “question”: “Do you think that your injury will…”.

Bohman et al.

Bohman et al. BMC Musculoskeletal Disorders 2012 13:264   doi:10.1186/1471-2474-13-264

Open Data