Table 3. Non-return to work: Odds ratios for the univariable, multivariable and the reduced model after random forest selection process.

	Univariable		Multivariable		Reduced model after conditional random forest
Variables	Odds Ratio (95% CI)	p-value	Odds Ratio (95% CI)	p-value	Odds Ratio(95% CI)	p-value
Woman	0.89 (0.68 to 1.18)	0.431	1.03 (0.72 to 1.47)	0.873
Age, per 10 years	1.14 (1.03 to 1.26)	0.009	1.18 (1.04 to 1.34)	0.009	1.19 (1.07 to 1.34)	0.005
Living alone	0.83 (0.66 to 1.03)	0.087	1.10 (0.83 to 1.46)	0.502
Higher education	0.45 (0.36 to 0.55)	<0.0001	0.75 (0.55 to 1.02)	0.066	0.79 (0.59 to 1.07)	0.128
Worked 100% before injury	0.93 (0.69 to 1.25)	0.629	0.85 (0.59 to 1.22)	0.371
Qualified work before injury	0.42 (0.34 to 0.52)	<0.0001	0.78 (0.57 to 1.06)	0.113	0.75 (0.56 to 1.01)	0.062
Work related injury	1.57 (1.27 to 1.93)	<0.0001	1.33 (1.03 to 1.74)	0.031	1.18 (0.93 to 1.5)	0.165
Litigation	1.52 (1.07 to 2.17)	<0.0001	1.25 (0.82 to 1.91)	0.29
Local native language	0.40 (0.32 to 0.49)	<0.0001	0.64 (0.48 to 0.86)	0.003	0.67 (0.51 to 0.88)	0.004
Location : Lower Leg and Pelvis	0.75 (0.60 to 0.92)	0.006	0.65 (0.38 to 1.12)	0.122
Location : Back	1.09 (0.84 to 1.41)	0.529	0.86 (0.47 to 1.54)	0.606
Location : Shoulder	1.26 (1.01 to 1.56)	0.042	0.88 (0.5 to 1.56)	0.656
Location : Multiple Injuries	1.09 (0.75 to 1.58)	0.646	1.00 (reference)
Severity of injury, AIS	0.96 (0.84 to 1.09)	<0.0001	1.10 (0.93 to 1.30)	0.284
Pain 0 to 100, per 10 points	1.15 (1.11 to 1.20)	<0.0001	1.05 (1.00 to 1.10)	0.068	1.04 (0.99 to 1.09)	0.114
Self-perceived quality of life 0 to 100, per 10 points	0.88 (0.85 to 0.92)	<0.0001	0.95 (0.91 to 1.00)	0.046	0.95 (0.91 to 1.00)	0.034
Chronicity	1.28 (1.13 to 1.46)	<0.0001	1.06 (0.90 to 1.25	0.506	1.04 (0.88 to 1.21)	0.661
Diagnostic dilemma	1.18 (1.00 to 1.39)	0.051	0.92 (0.74 to 1.13)	0.429
Severity of symptoms	3.19 (1.55 to 6.56)	0.002	2.53 (1.02 to 6.24)	0.045
Diagnostic challenge	1.41 (1.21 to 1.64)	<0.0001	1.12 (0.94 to 1.35)	0.209
Restrictions in coping	1.53 (1.36 to 1.73)	<0.0001	1.16 (0.95 to 1.41)	0.149	1.07 (0.9 to 1.27)	0.449
Psychiatric dysfunction	1.30 (1.15 to 1.47)	<0.0001	0.82 (0.66 to 1.00)	0.054
Resistance to treatment	2.02 (1.66 to 2.45)	<0.0001	1.10 (0.78 to 1.56)	0.58	1.07 (0.84 to 1.38)	0.572
Psychiatric symptoms	1.77 (1.53 to 2.04)	<0.0001	1.00 (0.80 to 1.24)	0.986	1.00 (0.81 to 1.23)	0.980
Restrictions in integration	1.81 (1.62 to 2.02)	<0.0001	1.41 (1.22 to 1.61)	<0.0001	1.42 (1.24 to 1.61)	<0.0001
Social dysfunctioning	1.72 (1.45 to 2.04)	<0.0001	1.17 (0.93 to 1.49)	0.184	1.10 (0.88 to 1.37)	0.426
Residential instability	1.89 (1.38 to 2.58)	<0.0001	1.34 (0.91 to 1.97)	0.135
Restrictions of network	1.73 (1.48 to 2.03)	<0.0001	1.25 (1.01 to 1.53)	0.037	1.26 (1.03 to 1.54)	0.022
Intensity of treatment	1.19 (1.03 to 1.36)	0.015	1.14 (0.96 to 1.36)	0.148
Treatment experience	1.04 (0.90 to 1.21)	0.59	0.94 (0.78 to 1.13)	0.496
Organization of care	1.77 (1.54 to 2.05)	<0.0001	1.21 (1.00 to 1.46	0.05	1.28 (1.07 to 1.54)	0.008
Appropriateness of referral	1.80 (1.50 to 2.15)	<0.0001	0.93 (0.68 to 1.28)	0.671
Complications and life-threat	2.02 (1.65 to 2.47)	<0.0001	1.23 (0.94 to 1.60)	0.133	1.29 (1.00 to 1.66)	0.052
Mental health threat	1.75 (1.48 to 2.06)	<0.0001	0.96 (0.73 to 1.26)	0.764	0.89 (0.69 to 1.13)	0.337
Social vulnerability	1.78 (1.53 to 2.06)	<0.0001	1.16 (0.95 tp 1–41)	0.15	1.19 (0.99 to 1.43)	0.071
Coordination of healthcare	2.01 (1.63 to 2.49)	<0.0001	1.30 (0.99 to 1.7)	0.059	1.23 (0.95 to 1.59)	0.117

Odds Ratios of the different models in the development sample, with corresponding 95% confidence intervals (CI).