The Friedrich-Lively Instrument to Assess the Impact of Schizophrenia on Siblings (FLIISS): Part II--reliability and validity assessment.

Siblings of persons with schizophrenia who provide primary or secondary care for their sibling and support to parents may experience stress, decreased quality of life, grief, chronic illness, depression, and anxiety. The effects on siblings have not been widely studied and there have not been appropriate instruments to measure the types and degree of stress and associated mental, emotional, and physical distress. The Friedrich-Lively Instrument to Assess the Impact of Schizophrenia on Siblings (FLIISS) is a comprehensive instrument based on extensive research and work with siblings of persons with schizophrenia. Construction of the FLIISS and its relationship to a conceptual model of stress is presented in an article (Part I) elsewhere in this issue. In this article (Part II), reliability results and construct validity are reported for the FLIISS. The FLIISS demonstrates appropriate usefulness and content, acceptable internal consistency, and strong construct validity. Health professionals can use the instrument for collecting information that will increase their ability to identify sources of stress faced by siblings of persons with schizophrenia and develop interventions to help these siblings.