Cross-cultural adaptation and validation of the Portuguese version of “The assessment of knowledge in ankylosing spondylitis patients by a self-administered questionnaire”

Knowledge is an important factor in patients with ankylosing spondylitis regarding the adoption of appropriate behaviours and education. The aim of this study was to culturally adapt and validate "The assessment of knowledge in ankylosing spondylitis patients by a self-administered questionnaire" for the Portuguese population with ankylosing spondylitis. The Portuguese version of "The assessment of knowledge in ankylosing spondylitis patients by a self-administered questionnaire" was administered to a sample of 180 subjects, from which 63 individuals responded. The adaptation process involved translation, back-translation and submission to a committee of experts in the area, culminating with a Portuguese version of the instrument. Next, the scale reliability and validity were assessed. There was a statistically significant decrease from test to retest, although the intra-class correlation coefficient between test and retest was 0.76 (95 % CI 0.61-0.86), which was considered good. From 180 individuals, 63 (35.0 %) subjects were available for the present study. The proportion of individuals that correctly answered each item ranged from 19 to 92 %, corresponding to items 8 and 13, respectively. The mean number of correct answers was 8.5 [mean (SD) = 2.4] in 12 questions. The proposed Portuguese version of the ankylosing spondylitis knowledge scale showed good reliability, reproducibility and construct validity.