Feasibility, reliability and validity of the Spanish version of Psychiatric Assessment Schedule for Adults with Developmental Disability: A structured psychiatric interview for intellectual disability

Background. Over 30% of people with intellectual disability (ID) have a comorbid psychiatric disorder. However, there are few assessment instruments available for international use and cross-cultural validation studies of these instruments are rare. The aim of the present study was to standardize the Spanish version of the Psychiatric Assessment Schedule for Adults with Developmental Disability (PAS-ADD-10), a semi-structured interview for people with ID. Methods. After a conceptual translation, feasibility (i.e. applicability, acceptability and practicality) and reliability analyses were carried out. The predictive validity of the PAS-ADD-10 CATEGO-5 codings was also examined (i.e. positive and negative predictive values). Four independent raters with wide-ranging experience in quantitative evaluation and psychiatric assessment of ID evaluated a sample of 80 subjects with ID and borderline intellectual functioning at the AFANAS occupational centre in Jerez, Southern Spain. The ICD-10 codes were used for psychiatric diagnosis. Results. The practicality of the PAS-ADD-10 is limited because of the need for previous standardization of SCAN interviews. Nevertheless, its overall feasibility was judged adequate by raters and the PAS-ADD-10 was considered extremely useful for training. Test-retest and inter-rater reliability kappa values were moderate to high. The CATEGO coding showed limited validity because of overdiagnosis of anxiety disorders and underdiagnosis of mood and psychotic disorders (positive predictive value = 74%, negative predictive value = 76%). Conclusions. The PAS-ADD-10 is a useful tool for standard psychiatric assessment of people with ID; however, CATEGO codings show low validity and a series of modifications should be considered before this instrument is used extensively in Spain. In this regard, a study on the clinical usefulness of the PAS-ADD-10 in patients with ID and severe mental disorders has been undertaken.