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Table 3 Generalized estimating equation model for the treatment effect

From: Effect of vitamin B12 on the symptom severity and psychological profile of fibromyalgia patients; a prospective pre-post study

Parameter

B

Standard error

95% confidence interval

p value

Lower

Upper

Model 1

Time: before

6.36

3.03

0.41

12.31

0.03

Time: after*

Reference

–

–

–

–

Change in HADS_ Anxiety

2.38

0.51

1.38

3.38

 < 0.01

Model 2

Time: before

9.20

2.79

3.72

14.69

 < 0.01

Time: after*

Reference

–

–

–

–

HADS-anxiety

0.93

0.63

 − 0.30

2.17

0.14

HADS-depression

2.19

0.67

0.87

3.51

 < 0.01

Marital status: married

12.10

4.53

3.22

20.98

 < 0.01

Marital status: single

Reference

–

–

–

–

Age

 − 0.21

0.28

 − 0.78

0.34

0.45

Time from diagnosis

1.67

0.70

0.29

3.05

0.01

  1. Model 1 is adjusted for change of anxiety and model 2 is adjusted for baseline anxiety, depression, marital status, age, and time from diagnosis
  2. HADS hospital anxiety and depression scale
  3. *This parameter is redundant