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Table 3 The mean delta score [standard deviation (SD)] (post-treatment values minus pre-treatment values) of pain measures (FIQ, PPT, analgesic consumption, tender points) and sleep quality (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

2A. Secondary outcomes     
Treatment Mean (SD) Mean difference (SD) Median of the difference (Quartile 75;25) P Value SDM CI 95%
Fibromyalgia Impact Questionnaire (FIQ) score    
Amitriptyline (n = 21) 41.16 (14.61) vs. 53.78 (12.83 ) -12.19 (16.27) -13.78 (-24.39,-4.95)**b 0.04 0.88 (0.43-1.33)
Melatonin (n = 21) 46.42 (16.18) vs. 64.87 (12.83) -17.73 (13.0) -16.30 (-22.29,-12.94)**b   1.28 (0.83-1.74)
Amitriptyline + melatonin (n = 21) 40.89 (10.94) vs. 65.15 (9.94) -24.65 (12.14) -26.41 (-32.59,-14.50)**a   1.79 (1.29-2.28)
b. Mean pressure pain threshold (PPT) in (kg/cm2/second)    
Amitriptyline (n = 21) 2.34 (0.45) vs. 2.05 (0.24) 0.29 (0.31) 0.2 (0.1, 0.5)**b 0.03 0.69 (0.34-1.04)
Melatonin (n = 21) 2.47 (0.33) vs. 1.99 (0.16) 0.47 (0.34) 0.4 (0.23, 0.55)**b   1.13 (0.79-1.47)
Amitriptyline + melatonin (n = 21) 2.70 (0.23) vs. 2.17(0.21) 0.54 (0.60) 0.6 (0.5, 0.7)**a   1.27 (0.9-1.64)
Analgesic doses (mean during the last week of treatment)    
Amitriptyline (n = 21) 1.35 (1.2) vs. 2.07 (1.37) -0.72 (1.40) -0.22 (-0.82, 0.54)* 0.98 1.03 (0.33-1.67)
Melatonin (n = 21) 1.33 (1.29) vs. 2.16 (1.20) -0.79 (1.52) -0.14 (-1, 0.57)*   1.09 (0.51-1.66)
Amitriptyline + melatonin (n = 21) 1.04 (0.92) vs. 2.10 (1.03) -1.1 (1.14) -0.35 (-0.74, 0.47)*   1.33 (0.77-1.89)
Number of tender points     
Amitriptyline (n = 21) 10.62 (3.36) vs. 14.10 (2.27) -3.45 (0.84) - 4 (-5, 1.25)** 0.89 1.99 (1.35-2.63)
Melatonin (n = 21) 10.95 (2.94) vs. 14.71 (1.70) - 3.75 (2.46) - 4 (-6.5,-2.25)**   2.17 (1.53-2.80)
Amitriptyline + melatonin (n = 21) 10.29 (3.15) vs. 14.61 (2.32) - 4.18 (1.91) - 4 (-5,-3)**   2.41 (1.72-3.10)
Pittsburgh Sleep Questionnaire    
Amitriptyline (n = 21) 11.84 (5.82) vs. 19.31 (6.58) -7.47 (7.34) -7 (-11,-4)* 0.94 1.07 (0.51-1.63)
Melatonin (n = 21) 16.68 (8.38) vs. 22.67 (7.69) -6.42 (6.53) -5 (-11,-2)*   0.9 (0.38-1.44)
Amitriptyline + melatonin (n = 21) 16.11 (8.40) vs. 24.28 (7.79) -7.58 (1.91) -8 (-12,-1.5)*   1.06 (0.52-1.59)
  1. *P < 0.01, **P < 0.0001 Comparisons using Mixed ANOVA model.
  2. Mixed ANOVA model. Mean difference of group. Different superscripts (a, b, and c) indicate significant differences among treatment groups according to the Bonferroni test.
  3. Standardized mean difference (SMD) [(pre minus post)/pool baseline standard deviation] with confidence interval (CI) 95%. The size effect was interpreted as follows: small, 0.20 to 0.40; moderate, 0.50-0.70; and large, 0.80 or higher.