Glasgow anxiety scale for people with an intellectual disability (GAS-ID): validation for Spanish population

Purpose Anxiety disorder is a common mental health problem in people with intellectual disabilities. Although this affects their quality of life, in Spain, there are no validated tools to evaluate the symptomatology of anxiety in people with intellectual disabilities. The aim of this study is to validate the Glasgow Anxiety Scale for people with an intellectual disability (GAS-ID) in the Spanish population. Design/methodology/approach The Spanish version of the GAS-ID was produced by back translation and was administered to 120 adults with intellectual disabilities. The psychometric analyses included internal consistency using the Cronbach’s alpha coefficient, inter-rater and test-retest reliability were determined using intra class correlation and Pearson correlation coefficients and, finally, factor analysis with Varimax rotation to confirm the construct validity of the questionnaire. Findings Cronbach’s alpha was 0.86 for the overall questionnaire. The intraclass correlation coefficient showed a good level of agreement in both test-retest (0.90) and inter-rater (0.91) analysis and the Pearson correlation showed a good significance in all dimensions and in the total scale. Varimax rotation factor analysis revealed four well-defined factors. Originality/value The GAS-ID is a feasible and reliable instrument for assessing anxiety symptoms in adults with mild and moderate intellectual disabilities, offering better diagnoses and therefore a more accurate treatment for the Spanish population with intellectual disabilities.