Validation in Spanish population of the family objective and subjective burden interview (EFOS-II) for relatives of patiens with schizophrenia

Introduction. The family burden experienced by caregivers of people with schizophrenia is one of the most relevant consequences of this disorder. This paper aims to show the validity and reliability of the Spanish version of the Family Burden Interview Schedule (FBIS) designed to assess objective and subjective family burden for people with schizophrenia. Method. Design: cross sectional study. Participants: 356 patients fulfilling DSM-IV criteria for schizophrenia from four Spanish geographic areas (Barcelona, Madrid, Pamplona and Granada) and 205 main caregivers of these patients were assessed. Material: caregivers were assessed with the Family Burden Interview Schedule (FBIS) Spanish version (ECFOS-II), which assesses family burden in eight different modules: activities of daily living, disrupted behaviors restraint, expenses, caregiver's routine, concern, help, repercussions on health, and assessment of general burden. Patients were also assessed with PANSS, DAS-sv and GAF. Statistical analysis: in order to assess internal consistency, parametrical tests of Cronbach's alpha were undertaken. To compute test-retest reliability Cohen's kappa and Weighted kappa were used. A principal component analysis was undertaken for assessing construct validity. Convergent validity was assessed with Spearman and Pearson correlation coefficients respectively, relating the instrument with the psychopathological (PANSS) and disability scale (DAS-sv) and general functioning (GAF). Moreover, a description of the viability of the ECFOS-II was described by a questionnaire especially designed for this purpose. Results. Cronbach's alpha coefficient was 0.85 for the global assessment. Test-retest coefficients were very high both for Cohen's kappa and for Weighted kappa, most values being between 0.61 and 1. Principal component analysis detected four factors that coincide with the modules of the original schedule. In the convergent validity we found that these factors are related with the symptom, disability and global functioning characteristics of the patients. Conclusions. ECFOS-II results in a valid and reliable instrument for assessing family burden experienced by caregivers of people with schizophrenia.