TY - JOUR
T1 - Assessing differential item functioning for the Social Appearance Anxiety Scale
T2 - a Scleroderma atient-centred Intervention Network (SPIN) Cohort Study
AU - Sommer, Sophia J.
AU - Harel, Daphna
AU - Kwakkenbos, Linda
AU - Carrier, Marie Eve
AU - Gholizadeh, Shadi
AU - Gottesman, Karen
AU - Leite, Catarina
AU - Malcarne, Vanessa L.
AU - Thombs, Brett D.
N1 - Funding Information:
Funding SPIN has been funded by grants from the Canadian Institutes of Health Research (TR3-119192, PJT-148504, PJT-149073, SCT-162963), the Canadian Initiative for Outcomes in Rheumatology Care, and the Arthritis Society. In addition, SPIN has received institutional contributions from the Female Davis Institute for Medical Research of the Jewish General Hospital, Montreal, Canada and from McGill University, Montreal, Canada. SPIN has also received support from Scleroderma Canada, the Scleroderma Society of Ontario, Sclérodermie Québec, the Scleroderma Society of Nova Scotia, the Scleroderma Association of British Columbia, Scleroderma Manitoba, and the Scleroderma Society of Saskatchewan.
Funding Information:
SPIN has been funded by grants from the Canadian Institutes of Health Research (TR3-119192, PJT-148504, PJT-149073, SCT-162963), the Canadian Initiative for Outcomes in Rheumatology Care, and the Arthritis Society. In addition, SPIN has received institutional contributions from the Female Davis Institute for Medical Research of the Jewish General Hospital, Montreal, Canada and from McGill University, Montreal, Canada. SPIN has also received support from Scleroderma Canada, the Scleroderma Society of Ontario, Sclerodermie Quebec, the Scleroderma Society of Nova Scotia, the Scleroderma Association of British Columbia, Scleroderma Manitoba, and the Scleroderma Society of Saskatchewan.
Publisher Copyright:
© Author(s) (or their employer(s)) 2020.
PY - 2020/10/12
Y1 - 2020/10/12
N2 - 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.
AB - 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.
KW - anxiety disorders
KW - rheumatology
KW - statistics & research methods
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U2 - 10.1136/bmjopen-2020-037639
DO - 10.1136/bmjopen-2020-037639
M3 - Article
C2 - 33046467
AN - SCOPUS:85092885725
SN - 2044-6055
VL - 10
JO - BMJ Open
JF - BMJ Open
IS - 10
M1 - 037639
ER -