Factor structure and convergent validity of the Derriford Appearance Scale-24 using standard scoring versus treating 'not applicable' responses as missing data: a Scleroderma Patient-centered Intervention Network (SPIN) cohort study. Issue 3 (6th March 2018)

• Record Type: Journal Article
• Authors: Merz, Erin L; Kwakkenbos, Linda; Carrier, Marie-Eve; Gholizadeh, Shadi; Mills, Sarah D; Fox, Rina S; Jewett, Lisa R; Williamson, Heidi; Harcourt, Diana; Assassi, Shervin; Furst, Daniel E; Gottesman, Karen; Mayes, Maureen D; Moss, Tim P; Thombs, Brett D; Malcarne, Vanessa L
• Other Names: author non-byline.; Baron Murray author non-byline.; Bartlett Susan J author non-byline.; Den Hoogen Frank Van author non-byline.; Mouthon Luc author non-byline.; Nielson Warren R author non-byline.; Riggs Robert author non-byline.; Sauve Maureen author non-byline.; Wigley Fredrick author non-byline.; Maia Angela Costa author non-byline.; El-Baalbaki Ghassan author non-byline.; Ells Carolyn author non-byline.; Den Ende Cornelia Van author non-byline.; Fligelstone Kim author non-byline.; Fortune Catherine author non-byline.; Frech Tracy author non-byline.; Godard Dominique author non-byline.; Harel Daphna author non-byline.; Hudson Marie author non-byline.; Impens Ann author non-byline.; Jang Yeona author non-byline.; Johnson Sindhu R author non-byline.; Kennedy Ann Tyrell author non-byline.; Körner Annett author non-byline.; Larche Maggie author non-byline.; Leite Catarina author non-byline.; Marra Carlo author non-byline.; Nielsen Karen author non-byline.; Pope Janet author non-byline.; Portales Alexandra author non-byline.; Rodriguez Reyna Tatiana Sofia author non-byline.; Schouffoer Anne A author non-byline.; Steele Russell J author non-byline.; Suarez-Almazor Maria E author non-byline.; Welling Joep author non-byline.; Wong-Rieger Durhane author non-byline.; Agard Christian author non-byline.; Albert Alexandra author non-byline.; André Marc author non-byline.; Arsenault Guylaine author non-byline.; Benmostefa Nouria author non-byline.; Benzida Ilham author non-byline.; Berthier Sabine author non-byline.; Bissonnette Lyne author non-byline.; Boire Gilles author non-byline.; Bruns Alessandra author non-byline.; Carreira Patricia author non-byline.; Casadevall Marion author non-byline.; Chaigne Benjamin author non-byline.; Chung Lorinda author non-byline.; Cohen Pascal author non-byline.; Dagenais Pierre author non-byline.; Denton Christopher author non-byline.; Domsic Robyn author non-byline.; Dunne James V author non-byline.; Farge-Bancel Dominique author non-byline.; Fortin Paul author non-byline.; Gill Anna author non-byline.; Gordon Jessica author non-byline.; Granel-Rey Brigitte author non-byline.; Grange Claire author non-byline.; Gyger Genevieve author non-byline.; Hachulla Eric author non-byline.; Hatron Pierre-Yves author non-byline.; Herrick Ariane L author non-byline.; Hij Adrian author non-byline.; Hinchcliff Monique author non-byline.; Ikic Alena author non-byline.; Jones Niall author non-byline.; De B Fernandes Artur Jose author non-byline.; Kafaja Suzanne author non-byline.; Khalidi Nader author non-byline.; Korman Benjamin author non-byline.; Lambert Marc author non-byline.; Launay David author non-byline.; Liang Patrick author non-byline.; London Jonathan author non-byline.; Manning Joanne author non-byline.; Martin Thierry author non-byline.; Masetto Ariel author non-byline.; Mekinian Arsene author non-byline.; Paule Romain author non-byline.; Regent Alexis author non-byline.; Rivière Sébastien author non-byline.; Robinson David author non-byline.; Roux Sophie author non-byline.; Smets Perrine author non-byline.; Smith Doug author non-byline.; Sobanski Vincent author non-byline.; Spiera Robert author non-byline.; Steen Virginia author non-byline.; Sutton Evelyn author non-byline.; Terrier Benjamin author non-byline.; Thorne Carter author non-byline.; Varga John author non-byline.; Wilcox Pearce author non-byline.; Delisle Vanessa C author non-byline.; Levis Brooke author non-byline.; Pepin Mia R author non-byline.;
• Is Part Of: BMJ open. Volume 8:Issue 3(2018)
• Publication Date: 2018-03-06
• Subjects: derriford appearance scale -- Das-24 -- systemic sclerosis -- psychometrics -- confirmatory factor analysis; Medicine -- Research -- Periodicals; 610.72
• DOI: 10.1136/bmjopen-2017-018641
• Languages: English
• ISSNs: 2044-6055

Abstract

Abstract : Objective: Valid measures of appearance concern are needed in systemic sclerosis (SSc), a rare, disfiguring autoimmune disease. The Derriford Appearance Scale-24 (DAS-24) assesses appearance-related distress related to visible differences. There is uncertainty regarding its factor structure, possibly due to its scoring method. Design: Cross-sectional survey. Setting: Participants with SSc were recruited from 27 centres in Canada, the USA and the UK. Participants who self-identified as having visible differences were recruited from community and clinical settings in the UK. Participants: Two samples were analysed (n=950 participants with SSc; n=1265 participants with visible differences). Primary and secondary outcome measures: The DAS-24 factor structure was evaluated using two scoring methods. Convergent validity was evaluated with measures of social interaction anxiety, depression, fear of negative evaluation, social discomfort and dissatisfaction with appearance. Results: When items marked by respondents as 'not applicable' were scored as 0, per standard DAS-24 scoring, a one-factor model fit poorly; when treated as missing data, the one-factor model fit well. Convergent validity analyses revealed strong correlations that were similar across scoring methods. Conclusions: Treating 'not applicable' responses as missing improved the measurement model, but did not substantively influence practical inferences that can be drawn from DAS-24 scores. Indications of item redundancy and poorly performing items suggest that the DAS-24 could be improved and potentially shortened.