Table 2.

Demographics, comorbidity and pain characteristics at baseline among the control persons and the persons with chronic neck pain. SD = standard deviation, IQR = Interquartile range

N = 38	Chronic neck pain				Control
	n	Mean	Median	Min, Max	n	Mean	Median	Min, Max
		(SD)	(IQR)			(SD)	(IQR)
Age (mean)	26	51	52.5	23,66	12	34.6	27	22, 61
		[5, 12]	(47, 63)			(16,0)	(23, 53.5)
Sex (%)
Women	19	73			7	60
Men	7	27			5	40
Education (%)
Elementary school	4	15			0	0
High school	9	35			6	50
College, university	13	50			6	50
Physical activity (%)
1 Sedentary	1	4			1	8
2 Moderate	15	58			4	33
3 Regular	9	35			5	42
4 Intense	1	4			2	17
Smoking (%)	4	16			0	0
Alcohol consumption (> 9 units/week)(%)	5	19			4	33
HADS – Anxiety	25	1.2	1.1	0.71, 2.00	12	1.2	1.1	0.71, 1.86
		(0.40)	(0.86, 1.57)			(0.32)	(0.93, 1.29)
Work percentage	26	54	77.5	0, 100	12	88	100	5, 100
		(47.2)	(0, 100)			(29.8)	(100, 100)
Sick leave or sickness benefit	26	26	0	0, 100	12	0	0	0, 0
		(43.9)	(0.0,75.0)			(0.0)	(0, 0)
SMBQ	25	1.6	1.6	1.14, 2.55	12	1.4	1.5	0.64, 1.86
		(0.37)	(1.32, 1.86)			(0.33)	(1.32, 1.55)
Sleep Quality (insomnia)	26	3.8	4.5	1.25, 5.25	12	4.6	4.6	3.75, 5.25
		(1.30)	(2.50, 4.75)			(0.56)	(4.25, 5.00)
Awakening index	26	4.2	4.5	1.33, 6.00	12	4.7	5.0	1.67, 5.67
		(1.32)	(3.00, 5.33)			(1.04)	(4.67, 5.33)
Sleepiness/fatigue	26	4.3	4.5	2.20, 6.00	12	4.6	4.6	3.00,6.00
		(1.02)	(3.60, 5.00)			(0.91)	(4.20, 5.00)
Pain sites	26	10	9	0,23	4	1.75	1.5	1,3
		(6.26)	(6.0, 13.0)			(0.96)	(1.0,2.5)