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Table 1 Epidemiological and clinical characteristics at baseline, according to the treatment group, values are given as the mean (SD) or frequency (n=63)

From: Melatonin analgesia is associated with improvement of the descending endogenous pain-modulating system in fibromyalgia: a phase II, randomized, double-dummy, controlled trial

  Amitriptyline (n = 21) Melatonin (n = 21) Amitriptyline + melatonin (n = 21) P value
Age (years) 49.80 ± (8.91) 47.40 ± (7.84) 49.72 ± (7.24) 0.59
Body index 27.65 ± (3.91) 27.18 ± (4.04) 27.58 ± (4.62) 0.60
Education (years) 10.95 ± (5.09) 11.30 ± (3.76) 8.22 + (5.6) 0.39
Smoking (n/%) 2 (9,5) 2 (9,5) 1 (5) 0.83
Clinical Comorbidity Yes/No 10 (47,6) 9 (42,9) 13 (65) 0.33
Hypertension (n/%) 5 (23,8) 5 (23,8) 8 (40)  
Hypothyroidism (n/%) 3 (14,3) 1 (4,8) 7 (35)  
Asthma (n/%) 1 (4,8) 1 (4,8) 2 (10)  
Other (n/%) 3 (15) 0 (0) 1 (4,8)  
Global pain on visual analogue scale 62.88 ± (14.26)a 64.90 ± (15.44)a 69.57 ± (10.94)b 0.03
FIQ 53.78 ± (12.83 )a 64.87 ± (12.83)b 65.15 ± (9.94)b 0.005
Pain catastrophizing scale for the Brazilian population (B-PCS)   
  25.90 ± (10.38) 32.90 ± (12.28) 25.90 ± (10.38) 0.07
Pittsburgh Sleep Questionnaire 19.31 ± (6.58) 22.67 ± (7.69) 24.28 ± (7.79) 0.16
Hamilton Depression Scale 17.61 ± (6.37) 21.70 ± (5.88) 17.61 ± (6.33) 0.05
Pain pressure threshold 2.17 ± (0.21)a 1.99 ± (0.16)b 2.05 ± (0.24)a 0.04
Brain-derived neurotrophic factor (BDNF)    
Mean (SD) 48.28 ± (24.00) 52.54 ± (23.87) 48.28 ± (27.34)  
Median [interquartile (IQ) 25;75] 45.51 (12.8;101.51) 54.78 (20.66;97.85 37.51 (18.75;92.3) 0.79
Psychiatric disease (SCID-I) 6 (76%) 15 (71%) 13 (65) 0.45
Depression 8 (38%) 1 (62%) 11 (55%)  
Anxiety 11(52%) 12 (57%) 5 (25%)  
Analgesic used weekly in last 3 months     
Median (Q25-75) 6 (3;28) 7 (2;26) 7 (3;29 0.91
Analgesic use: days/week in last 3 months¥   
(<4 = no, ≥4 = times) 20 (95%) 20 (95%) 17 (85%) 0.43
A e aminophen/Dipirone 19 (90,5%) 16 (76,2%) 15 (75%)  
NSAID 7 (33,3%) 10 (47,6%) 9 (45%)  
Opioid 1 (4,8%) 0 0  
Active use of central nervous system active medication¥   
Yes/No 14 (66,7%) 16 (76%) 14 (70%) 0.16
Antidepressant (n/%) 14 (66,7%) 15 (71%) 13 (65%)  
Anticonvulsant (n/%) 2 (9,5%) 2 (9,5%) 1 (5)  
Benzodiazepine (n/%) 0 5 (23,8%) 2 (10%)  
  1. Different superscripts (a and b) indicate significant differences among treatment groups according to the Bonferroni test.
  2. Structured Clinical Interview for DSM-IV Axis I Disorders (SCID-I).
  3. Kruskal-Wallis Test.
  4. ¥Chi-Square or Fisher’s test.
  5. ANOVA.