1. Assessing differential item functioning for the Social Appearance Anxiety Scale: a Scleroderma Patient-centred Intervention Network (SPIN) Cohort Study
- Author
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Arsène Mekinian, Thierry Martin, Eric Hachulla, Carter Thorne, Andrea Benedetti, Brett D Thombs, Daniel E Furst, Virginia Steen, Paul R Fortin, Vincent Poindron, David Launay, Luc Mouthon, Mandana Nikpour, John Varga, Benjamin Chaigne, Sindhu R Johnson, Sébastien Rivière, Isabelle Boutron, Daphna Harel, Linda Kwakkenbos, Marie-Eve Carrier, Karen Nielsen, Alexandra Portales, Susan J Bartlett, Vanessa L Malcarne, Murray Baron, Karen Gottesman, Maureen D Mayes, Warren R Nielson, Robert Riggs, Maureen Sauve, Fredrick Wigley, Shervin Assassi, Angela Costa Maia, Ghassan El-Baalbaki, Carolyn Ells, Kim Fligelstone, Catherine Fortune, Tracy Frech, Dominique Godard, Marie Hudson, Ann Impens, Yeona Jang, Ann Tyrell Kennedy, Annett Körner, Maggie Larche, Catarina Leite, Carlo Marra, Janet Pope, Russell J Steele, Maria E Suarez-Almazor, Joep Welling, Durhane Wong-Rieger, Christian Agard, Alexandra Albert, Marc André, Guylaine Arsenault, Ilham Benzidia, Sabine Berthier, Lyne Bissonnette, Gilles Boire, Alessandra Bruns, Patricia Carreira, Marion Casadevall, Lorinda Chung, Pascal Cohen, Pierre Dagenais, Christopher Denton, Robyn Domsic, Sandrine Dubois, James V Dunne, Bertrand Dunogue, Alexia Esquinca, Regina Fare, Dominique Farge-bancel, Anna Gill, Jessica Gordon, Brigitte Granel-Rey, Claire Grange, Genevieve Gyger, Pierre-Yves Hatron, Ariane L Herrick, Adrian Hij, Monique Hinchcliff, Alena Ikic, Niall Jones, Suzanne Kafaja, Nader Khalidi, Marc Lambert, Patrick Liang, Hélène Maillard, Joanne Manning, Maria Martin, Ariel Masetto, François Maurier, Sheila Melchor, Susanna Proudman, Alexis Régent, David Robinson, Esther Rodriguez, Sophie Roux, Perrine Smets, Doug Smith, Vincent Sobanski, Robert Spiera, Wendy Stevens, Evelyn Sutton, Benjamin Terrier, Pearce Wilcox, Shadi Gholizadeh, François Rannou, Lindsay Cronin, Stephen Elrod, Cornelia van den Ende, Amy Gietzen, Christelle Nguyen, Michelle Richard, Ken Rozee, Anne A. Schouffoer, Nancy Stephens, Chase Correia, Artur Jose de B. Fernandes, Nancy Maltez, Isabelle Marie, Lydia Tao, Sami Harb, Elana J Bernstein, Sophia J Sommer, Shirley Haslam Geneviève Guillot, Tatiana Sofia Rodriguez Reyna, Sabrina Hoa, Angelica Bourgeault, and Andrea Carboni Jiménez
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Medicine - Abstract
Objectives The Social Appearance Anxiety Scale (SAAS) is a 16-item questionnaire developed to evaluate fear of appearance-based evaluation by others. The primary objective of this research was to investigate the existence of differential item functioning (DIF) for the 16 SAAS items, comparing patients who completed the SAAS in English and French, either to confirm that scores are comparable or provide guidance on calculating comparable scores. A secondary research objective was to investigate the existence of DIF based on sex and disease status. A tertiary research objective was to assess DIF related to language, sex, and disease status on the recently developed SAAS-5.Design This was a cross-sectional analysis using baseline data from patients enrolled in the Scleroderma Patient-centred Intervention Network (SPIN).Setting SPIN patients included in the present study were enrolled at 43 centres in Canada, USA, UK, France and Australia, with questionnaires completed in April 2014 to July 2019.Participants 1640 SPIN patients completed the SAAS in French (n=600) or English (n=1040).Primary and secondary measures The SAAS was collected along with demographic and disease characteristics.Results Six items were identified with statistically significant language-based DIF, four with sex-based DIF and one with disease type-based DIF. However, factor scores before and after accounting for DIF were similar (Pearson correlation >0.99), and individual score differences were small. This was true for both the full and shortened versions of the SAAS.Conclusion SAAS and SAAS-5 scores are comparable across language, sex, and disease-type, despite small differences in how patients respond to some items.
- Published
- 2020
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