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Table 1 Baseline characteristics*

From: Reduced hypothalamic-pituitary-adrenal axis activity in chronic multi-site musculoskeletal pain: partly masked by depressive and anxiety disorders

 

Controls

Chronic pain

P†

N ~

 

(n = 654)

(n = 471)

  

Pain

Days of pain in the prior 6 months

28.3 ± 49.1

109.0 ± 69.9

<0.001

 

Pain intensity

21.5 ± 14.7

52.3 ± 17.7

<0.001

 

Pain disability

9.4 ± 13.2

38.1 ± 24.9

<0.001

 

Cortisol sampling factors

Time of awakening

7:23 ± 1:07

7:34 ± 1:10

0.01

 

Working on day of sampling, %

67.2

48.5

<0.001

 

Sampling in month with more daylight, %

52.7

54.4

0.50

 

≤6 h sleep, %

21.0

37.3

<0.001

 

Sociodemographic factors

Age, years

43.3 ± 13.4

46.7 ± 11.8

<0.001

 

Women, %

56.7

73.5

<0.001

 

Education, years

13.1 ± 3.3

11.6 ± 3.3

<0.001

 

Lifestyle and disease factors

Body mass index, kg/m2

25.0 ± 4.2

26.2 ± 4.8

<0.001

 

Smoking, %

  

0.05

 

Never smoker

32.0

27.2

  

Former smoker

39.0

37.2

  

Current smoker

29.1

35.7

  

Alcohol use, %

  

<0.001

 

Non-drinker

20.9

38.2

  

Mild/moderate drinker

66.2

50.7

  

Heavy drinker

12.8

11.0

  

Physical activity, 1000 MET min./week

3.6 ± 3.0

3.9 ± 3.1

0.06

 

Number of chronic diseases

0.6 ± 0.8

0.9 ± 0.9

<0.001

 

Depression and anxiety factors

Lifetime depressive or anxiety disorder, %

  

<0.001

 

No disorder

40.4

12.7

  

Depressive disorder

19.0

16.8

  

Anxiety disorder

13.1

10.0

  

Comorbid depressive/anxiety disorder

27.5

60.5

  

Current depressive or anxiety disorder, %

35.9

67.5

<0.001

 

Antidepressant medication, %

  

<0.001

 

No antidepressant

83.2

71.3

  

SSRI

10.9

20.0

  

TCA

2.1

2.3

  

Other antidepressant

3.8

6.4

  

Cortisol measures

At awakening, nmol/l, median [IQR]

15.88 [12.42-20.17]

15.48 [12.07-19.45]

0.10

1105

AUCg, nmol/l/h

19.0 ± 7.0

18.8 ± 6.7

0.55

1025

AUCi, nmol/l/h

1.9 ± 6.5

2.6 ± 6.2

0.09

1025

Mean evening level, nmol/l, median [IQR]

4.68 [3.23-6.34]

4.90 [3.38-6.83]

0.07

1120

Diurnal slope, decline in nmol/l/h

0.77 ± 0.49

0.71 ± 0.39

0.05

1001

Cortisol suppression ratio, median [IQR]

2.43 [1.75-3.33]

2.35 [1.70-3.12]

0.23

1061

  1. MET = metabolic equivalent; SSRI = selective serotonin reuptake inhibitor; TCA = tricyclic antidepressant.
  2. AUCg = area under the curve with respect to the ground; AUCi = area under the curve with respect to the increase.
  3. * Values are mean ± SD unless otherwise indicated. †Based on independent-sample T test for continuous
  4. variables, chi-square test for dichotomous and categorical variables and Mann-Whitney U test for non-normally distributed variables. ~N-values that vary from total N = 1125 due to missings on individual cortisol measures.