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Table 3 Results of distribution and anchor based approaches (N = 46)

From: Distribution- and anchor-based methods to determine the minimally important difference on patient-reported outcome questionnaires in oncology: a structured review

  Number Percent
Distribution-based approach (N = 40)
 Distribution-reported
  0.2 SD at baseline 12 30
  0.3 SD at baseline 25 62.5
  0.5 SD at baseline 36 90
  SEM at baseline 31 77.5
  0.2 SD at follow-up 7 17.5
  0.3 SD at follow-up 14 35
  0.5 SD at follow-up 14 35
  SEM at follow-up 13 32.5
  0.2 SD of change 2 5
  0.3 SD of change 8 20
  0.5 SD of change 7 17.5
  SEM of change 5 12.5
Anchor-based approach (N = 43)
 Study design
  Cross-sectional 3 7.1
  Longitudinal design 39 92.9
 Number of anchors
  1 23 53.5
  2 8 18.6
  3 3 7
  4 3 7
   ≥ 5 6 13.9
 Anchors
  Overall rating of change 9 20.93
  Anchor derived from an external questionnaire 13 30.2
  Anchor derived from one dimension of the questionnaire studied 8 18.6
  Performance status 15 34.9
  MMSE 1 2.3
  Weight loss 1 2.3
  Other 10 23.3
 Correlation checked between anchor and the studied questionnaire
  Yes 32 76.2
  No 9 21.4
Criteria used to detect a moderate correlation (N = 32)
   ≥ 0.3 15 46.9
   ≥ 0.4 1 3.1
   ≥ 0.5 1 3.1
  Not reported 15 46.9
 Minimum N by anchor category
   ≤ 20 16 37.2
   > 20 18 41.9
  Not reported 9 20.9
  1. SD standard deviation, SEM standard error of measurement, MMSE mini mental state examination