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Table 1 Means, Standard Deviations, and Coefficient α for Patient Reported Outcome Measures, Baseline and Week 12

From: Validity and reliability of patient reported outcomes used in Psoriasis: results from two randomized clinical trials

  STUDY A STUDY B
  Baseline Week 12 Baseline Week 12
Patient-reported outcome measure N Mean (s.d.) Coefficient α N Mean (s.d.) Coefficient α N Mean (s.d.) Coefficient α N Mean (s.d.) Coefficient α
PSA Frequency: 8-item scale 493 13.21 (5.07) 0.858 446 8.22 (5.57) 0.927 594 13.79 (5.22) 0.875 572 8.51 (6.24) 0.940
PSA Frequency: 7-item scale 493 n/a 0.865 446 n/a 0.922 594 n/a 0.876 572 n/a 0.936
PSA Severity: 8-item scale 494 14.08 (5.55) 0.874 445 8.55 (6.42) 0.942 595 14.38 (5.62) 0.891 573 8.66 (6.71) 0.946
PSA Severity: 7-item scale 494 n/a 0.874 445 n/a 0.939 595 n/a 0.889 573 n/a 0.941
DLQI 483 11.75 (6.80) 0.871 437 6.69 (6.51) 0.921 586 12.18 (6.71) 0.869 571 7.07 (6.74) 0.919
VAS Itch 497 5.90 (2.68) n/a1 446 3.74 (3.03) n/a1 - - - - - -
NPS Itch - - - - - - 597 3.05 (1.41) n/a1 558 1.80 (1.50) n/a1
  1. 1 Coefficient α is not applicable for single-item scales