Reliability and validity of the Advanced Basal Cell Carcinoma Index (aBCCdex).
BACKGROUND
Patient-reported outcome (PRO) questionnaires were recently developed specifically for use with patients with advanced basal cell carcinoma (aBCC) and basal cell carcinoma naevus syndrome (BCCNS).


OBJECTIVE
To evaluate the measurement properties of PRO questionnaires for use in patients with aBCC or BCCNS.


METHODS
In total 129 patients from 10 clinical sites in the U.S.A. and the BCCNS Support Network completed the two newly developed questionnaires multiple times over 3 months. Patients also completed the Skindex-16 and the 12-Item Short-Form Health Survey as collateral measures. Psychometric properties of the questionnaires were evaluated, including internal consistency and test-retest reliability, construct and known-groups validity, and responsiveness.


RESULTS
Based on the results of exploratory factor analysis and clinical input, the two newly developed questionnaires were combined into a single questionnaire, called the aBCCdex, which is relevant for patients with both aBCC and BCCNS. The internal consistency reliability was acceptable, and all aBCCdex scale scores correlated significantly with conceptually similar scales. When divided into groups that differed based on scores from collateral measures, aBCCdex scale scores differentiated between groups (known-groups validity) and were responsive to change.


CONCLUSIONS
The aBCCdex is a brief and comprehensive questionnaire appropriate for use with patients with aBCC and BCCNS. Its reliability and validity have been confirmed. Further research is necessary to estimate the minimally important difference in a larger patient population.
Health Outcomes Solutions, 2351 Via Tuscany, Winter Park, FL, 32789, U.S.A.
S D
SD
Mathias
Department of Dermatology, University of California San Francisco, San Francisco, CA, U.S.A.
M M
MM
Chren
Health Outcomes Solutions, Neuropsychiatric Research Institute, and University of North Dakota School of Medicine and Health Sciences, Fargo, ND, U.S.A.
R D
RD
Crosby
Health Outcomes Solutions, 2351 Via Tuscany, Winter Park, FL, 32789, U.S.A.
H H
HH
Colwell
Genentech, San Francisco, CA, U.S.A.
Y M
YM
Yim
Genentech, San Francisco, CA, U.S.A.
C
C
Reyes
Genentech, San Francisco, CA, U.S.A.
D M
DM
Chen
Departments of Dermatology, Internal Medicine, Head and Neck Surgery-Otolaryngology and Ophthalmology, Saint Louis University Cancer Center, Saint Louis University School of Medicine, St Louis, MO, U.S.A.
S W
SW
Fosko
D000293:Adolescent; D000328:Adult; D000368:Aged; D001478:Basal Cell Nevus Syndrome / Q000523:psychology*; D002280:Basal Cell Carcinoma / Q000523:psychology*; D017281:Cost of Illness; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D063868:Patient Outcome Assessment; D011594:Psychometrics; D011788:Quality of Life; D012878:Skin Neoplasms / Q000523:psychology*; D011795:Surveys and Questionnaires / Q000592:standards*; D055815:Young Adult