Understanding the Paradox of the More Clinically Meaningful Acne Global Severity Scale and the More Precise Acne Lesion Counts - PowerPoint PPT Presentation

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Understanding the Paradox of the More Clinically Meaningful Acne Global Severity Scale and the More Precise Acne Lesion Counts

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Title: Understanding the Paradox of the More Clinically Meaningful Acne Global Severity Scale and the More Precise Acne Lesion Counts


1
  • Understanding the Paradox of the More Clinically
    Meaningful Acne Global Severity Scale and the
    More Precise Acne Lesion Counts
  • Jonathan Wilkin, M.D.

2
Methodology
  • A model is the simplest system that has the
  • relevant properties.

3
Purpose of the Study
  • To characterize the relationship between the
  • Actual Number of acne lesions and the
  • Perceived Severity of acne lesions.

4
Materials Methods
  • 33 research subjects evaluated kodachromes of 2
    models for acne severity
  • 2 models with up to 200 acne lesions created by
    a professional theatrical cosmetic artist
  • Acne severity scored on a 10cm linear horizontal
    visual analogue scale
  • VAS scoring by digimatic calipers

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Conclusion
  • The psychometric model provides a curvilinear
    relationship between
  • the more clinically meaningful acne global
    severity scale and
  • the more precise acne lesion counts.

22
  • Historical Approach to Evidence for
    Effectiveness for Acne Drug Products for Mild to
    Moderate Acne
  • Jonathan Wilkin, M.D.

23
Success Criteria
  • Lesion Counts - total plus either inflammatory or
    noninflammatory
  • AND
  • Investigators Global Assessment (dichotomized
    into success and non-success)

24
Why Two Primary Endpoints
  • Lesion Counts - more accurate, precise,
  • objective, informs lesion type most responsive
  • Investigators Global - imprecise, subjective,
  • more clinically relevant

25
Variations Among NDAs
  • Different baseline lesion counts
  • Different lesion count analyses
  • absolute change
  • percent change
  • (variety of) transformed values
  • Different Investigators Global Scales

26
Questions
  • 1. Should the current success criteria using
    the co-primary endpoints be retained?
  • 2. How should lesion counts be analyzed?
  • 3. What investigators global severity scale
    should be used? At what level should it be
    dichotomized into success and non- success?

27
Acne vs. Lesion Type as Indication
  • Sponsors seek the indication of mild to moderate
    acne vulgaris as monotherapy.
  • Inflammatory lesions only as indication when
    difficult to demonstrate success in total lesion
    count change and investigators global evaluation.

28
Questions
  • 4. Should acne lesion types (inflammatory or
    noninflammatory) be medically acceptable
    indications?
  • 5. Should lesion counts be assessed at multiple
    time-points late in the study and averaged to
    increase power?

29
Questions (contd)
  • 6. How should the efficacy outcomes of clinical
    trials be portrayed in labeling to be maximally
    useful to clinicians and patients? What graphics
    and tables should be provided?

30
Goal
  • A guidance document that describes how the
    evidence for effectiveness of drug products for
    mild to moderate acne vulgaris may be obtained
    and analyzed.
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