DIAHORI'ppt

1
(No Transcript)
2

• Two measures to determine Minimal Clinically
  Important Change (MCIC)
• Riekie de Vet

Institute for Research in Extramural Medicine VU
University Medical Center Amsterdam
3
Minimal clinically important change

• Change instead of difference
• Clinically meaningful change
• Smallest detectable change or difference
  (measurement error)

4
Minimal clinically important change

• Anchor based versus distribution based
  approach Crosby presents 7 different methods for
  each approach
• Distribution based measures dont give a good
  sense of the clinical relevance of the change
• Anchor based approach uses a reference of a
  clinically relevant change

5
Group level versus individual level

• Group level comparisons of means and standard
  deviations in a trial
• Individual level comparison of percentages of
  patients who have a change larger than MCIC.
• Beaton et al. distinguish group level and
  individual level in methods to determine MCIC
• MDC group level ROC individual level

6
Two measures to determine MCIC

• Minimal detectable change and
• Optimal cut off point based on a ROC curve
• Both are anchor based methods with global
  perceived effect (GPE) as external criterion of
  clinically relevant change

7
Results of MCIC from a study on back pain
acute LBP chronic LBP MDC ROC MDC ROC
QBPDS 32.9 17.5 24.6 8.5 Pain (NRS) 4.7
3.5 4.5 2.5 Euroqol 0.58 0.09
0.28 0.09 Nicole van der Roer, Raymond
Ostelo, Maurits van Tulder, Riekie de Vet
8
Not one single MCIC value

• It depends on
• The method used
• (Sub)acute or chronic low back pain
• Influence of the initial scores
• Influence of length of interval of
  change-assessment
• Cut off point on GPE

9
Dependence on the method

• MDC cut off point based on the distribution of
  the unchanged persons (on GPE) 95 of unchanged
  persons show no change on the measurement
  instrument under study
• ROC optimal cut off point for a minimal number
  of misclassifications based on changed and
  unchanged persons

10
Distribution of change in NRS-pain in changed
and unchanged persons based on GPE
11
DIAGNOSTIC PARAMETERS Receiver operator Curve
(ROC)

• Area under the curve (AUC) surface under the
  curve a measure for the discriminating ability
  of the test

12
Discussion

• Not one single MCIC value
• Choice depends on acute and chronic back pain,
  initial values and length of the interval of
  change assessment

13
Discussion

• Which method do we prefer?
• - ROC-based value for MCIC is smaller.
• - It has the smallest number of
  misclassification.
• - However, it is smaller than the measurement
  error
• Has MCIC a meaning on group level?

14
(No Transcript)