Table 3.

Predictors for non-success in neck disability or arm pain at 12-months after surgery. Results are presented by Odds Ratio (OR) and bootstrapped 95% Confidence Intervals (CI) for the significant variables

	Non-success in neck disability (12-mo NDI1≥26*) n=1593	Non-success in arm pain (12-mo NRS-AP2≥3**) n=1546
Hard physical demands in work (vs computers/sitting still or light physical work)	1.56 (1.22, 2.00)	1.46 (1.15, 1.85)
High educational level (4 or more years of university) (vs high school or less than 4 years of university)	0.57 (0.41, 0.78)	0.51 (0.36, 0.71)
Pending litigation3 (vs none)	2.38 (1.70, 3.34)	1.68 (1.21, 2.33)
Previous neck surgery (vs not)	2.52 (1.61, 3.96)	2.01 (1.33, 3.03)
Duration of arm pain
< 3 months	Ref	Ref
3-12 months	1.81 (1.24, 2.65)	1.48 (1.01, 2.18)
> 1 year	2.51 (1.72, 3.66)	2.42 (1.66, 3.52)
Anxiety or depression	1.74 (1.38, 2.19)	-
Baseline NDI1 score
Low (0-40)	Ref	Ref
Medium (41-60)	4.20 (3.22, 5.48)	1.79 (1.40, 2.29)
High (> 60)	7.79 (5.07, 11.98)	2.53 (1.67, 3.85)
Baseline Arm Pain score
Low (0-4)	-	Ref
Medium (5-7)	-	1.66 (1.18, 2.32)
High (8-10)	-	2.04 (1.43, 2.90)
Foreign mother tongue (vs Norwegian)	-	1.71 (1.12, 2.61)
Smoking (vs no smoking)	-	1.44 (1.11, 1.85)
Nagelkerke R square	28.3%	17.3%
Discrimination, AUC4	0.78 (0.75, 0.82)	0.68 (0.64, 0.72)
Hosmer-Lemeshow test	p=0.455	p=0.753

* Number of participants with poor primary outcome n=768 (38%), ** Number of participants with poor secondary outcome n=698 (35,3%). ¹Neck Disability Index, 0-100 (no-maximal disability).²A Numeric Rating Scale for arm pain (0-10). ³Pending medical claim/litigation against the Norwegian public welfare agency fund concerning disability pension or pending medical compensation claim/litigation against private insurance companies or the public Norwegian System of Compensation to Patients.⁴Area Under the operating Curve