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Table 2 Patient example of contrast-values and the index ‘Treatment Duration Control’ (TDC)

From: The index ‘Treatment Duration Control’ for enabling randomized controlled trials with variation in duration of treatment of chronic pain patients

Reference item (i) Reference score (S1,i ) Later score (S2,i ) Contrast,C i =(S2,i - S1,i )/(S2,i + S1,i )
anamnesis:
(1) VAS-score of intensity of predominant pain (mm) 20 3 −0.739
(2) pain of the jaws (frequency) 3 1 −0.500
(3) stiffness and/or fatigue of the jaw muscles (frequency) 3 1 −0.500
(4) impaired movement of the jaw (frequency) 3 0 −1.000
clinical examination:
(5) pain intensity on the right side during passive jaw opening 2 0 −1.000
(6) pain intensity on the left side during passive jaw opening 2 0 −1.000
(7) pain intensity during palpation of the right deep masseter muscle 2 1 −0.333
(8) pain intensity during palpation of the left deep masseter muscle 2 1 −0.333
(9) pain intensity during palpation of the insertion of the right occipital muscle 2 0 −1.000
(10) pain intensity during palpation of the insertion of the left occipital muscle 2 1 −0.333
TDCanamnestic-items = (∑ Ci)/4 = [−0.739-0.500-0.500-1.000]/4) = −0.685
TDCclinical-items = (∑ Ci)/6 = 1.000-1.000-0.333-0.333-1.000-0.333]/6) = −0.666
TDC = (∑ Ci)/10 = [−0.739-(2 × 0.500)-(4 × 1.000)-(3 × 0.333)]/10) = −0.674
  1. Reference item (i), item with a sufficiently large score-value (see text) of which changes are followed. In this example of a patient, there are 4 reference items related to anamnestic questions and 6 items related to the clinical examination, thus 10 reference items in total (i = 1..10). S 2,i , score value of item i at a later visit (‘visit 2’) than S 1,i , the reference value item i that was observed for the first time at an earlier visit (‘visit 1’). Except the VAS-scores, all other scores originate from adjectival 0–4 point scales (Table 1). C i , Contrast-value being the ratio of the difference and sum between the second and the first score values of item i.. TDC, the index Treatment Duration Control, being the mean Contrast-value averaged across all items. TDCanamnestic-items and TDCclinical-items, mean TDC averaged across the anamnestic items and the clinical items respectively.