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A meta-analysis of the placebo response in vitiligo: Causes and consequences for the interpretation of clinical trials.

Authors
  • Speeckaert, Reinhart1
  • Speeckaert, Marijn M2
  • van Geel, Nanja1
  • 1 Department of Dermatology, Ghent University Hospital, Gent, Belgium. , (Belgium)
  • 2 Department of Nephrology, Ghent University Hospital, Gent, Belgium. , (Belgium)
Type
Published Article
Journal
Pigment Cell & Melanoma Research
Publisher
Wiley (Blackwell Publishing)
Publication Date
Jan 01, 2024
Volume
37
Issue
1
Pages
74–80
Identifiers
DOI: 10.1111/pcmr.13132
PMID: 37753945
Source
Medline
Keywords
Language
English
License
Unknown

Abstract

The current understanding of the placebo response in vitiligo is limited. Nonetheless, it is difficult to compare the outcomes of vitiligo trials if the repigmentation rates in placebo patients vary significantly. We conducted a meta-analysis of the placebo response in vitiligo trials. Overall, repigmentation rates in patients receiving placebo were 22%, ranging substantially from 0 to 60%. Repigmentation (>25%) was still relatively common for placebo (9.35%), but fell to 5% when >50% improvement was analyzed. Higher frequencies of placebo responses correlated with more repigmentation in the intervention groups. Facial vitiligo and sunlight exposure was linked to higher placebo responses. Roughly estimating the amount of improvement using quartiles (0-25, 25%-50%, 50%-75%, 75%-100% repigmentation) resulted in higher placebo rates compared to other assessment methods. In clinical studies with older patients, the ratio of placebo reactions to treatment responses was higher. This is likely because clinical trials with older patients reported less repigmentation after treatment than studies with younger patients. The percentual difference in affected body surface area during the study period ranged from 6.2% worsening to 17.6% improvement in the placebo groups. This high variability in placebo responses illustrates the need for standardized outcome measures and more head-to-head trials in vitiligo. © 2023 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

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