Assessing the content validity of the 2015 core domain set for vitiligo clinical trials: preliminary investigations for developing an updated version
Jolien Duponselle, Reinhart Speeckaert, Albert Wolkerstorfer, Julien Seneschal, Amit G Pandya, Iltefat Hamzavi, Amit Garg, Sandrine Herbelet, Liesbeth Delbaere, Nicoline Post, Caroline Le Poole, Andrea Tovar Garza, Harvey Lui, Martha Alejandra Morales-Sánchez, Somesh Gupta, Wedad Mostafa, Youwen Zhou, Mauro Picardo, Mehdi Rashighi, Davinder Parsad, Samia Esmat, Thierry Passeron, Laila Benzekri, Deepti Ghia, Giovanni Leone, Hyun Jeong Ju, Jung Min Bae, Marwa Abdallah, Markus Bohm, Michelle Rodrigues, David Rosmarin, Steven Tien Guan Thng, Victor Huang, Henry W Lim, John Ferguson, Paul Monteiro, Nicolle Maquignon, Jean-Marie Meurant, Georg Pliszewski, Marloes Zuidgeest, Stephen Taylor, Emma Rush, Noufal Raboobee, Caroline B Terwee, Phyllis Spuls, Nanja van GeelAbstract
Background
The 2015 core domain set (CDS) for vitiligo defines outcomes for clinical trials, comprising three essential and four recommended outcome domains/domain items. Periodic reassessment is required to ensure its continued relevance.
Objectives
To evaluate the content validity (relevance, comprehensiveness and comprehensibility) of the 2015 vitiligo CDS to inform a consensus-based update as part of a core outcome set, including core outcomes and core measurement instruments.
Methods
A roundtable discussion and three surveys reassessed the 2015 vitiligo CDS regarding relevance (≥ 70% agreement for ‘essential’), comprehensiveness (identification of missing domain items) and comprehensibility (clarity of terminology and descriptions).
Results
Fifty-three patients with vitiligo (group 1) and 37 experts (36 dermatologists and 1 researcher; group 2) participated. Two previously essential domains (‘Repigmentation’ and ‘Side effects/harms’) were re-endorsed as essential by both groups. ‘Maintenance of gained repigmentation’ was rated essential by patients only. Among previously recommended domains, ‘Quality of life’ was considered essential by both groups, whereas ‘Cosmetic acceptability of repigmentation’ and ‘Cessation of spreading of vitiligo’ were rated essential by patients only. ‘Tolerability/burden of treatment’ was not considered essential by either group. Frequently suggested missing items (outcomes and contextual factors) included psychological impact, treatment session duration, overall treatment duration, treatment costs, patient education and evaluation of associated autoimmune diseases. Proposed updates included refining domain terminology (e.g. vitiligo-specific/health-related quality of life; replacing ‘harms’ with ‘adverse events’) and addressing feasibility-related timeframes.
Conclusions
While the 2015 vitiligo CDS retains content validity for several domains, meaningful updates are warranted. These findings will inform the development of a revised and updated CDS.