Validity of a short functioning test (FAST) in Brazilian outpatients with bipolar disorder.

OBJECTIVES As the use of functioning outcomes is increasingly being advocated in multinational clinical trials and comparative studies, making available instruments with known validity and reliability in several languages is required. Here we present data on the Portuguese validation of the Functioning Assessment Short Test (FAST), which was explicitly designed to gauge functioning dimensions empirically linked to bipolar disorder. METHODS One hundred patients with bipolar disorder and matched controls were assessed with the FAST, which was evaluated regarding discriminant, content and construct validity, concurrent validity with functioning instruments, internal consistency and test-retest reliability. RESULTS The FAST displayed a five-factor structure very similar to its conceptualization, successfully discriminated patient and control groups, and correlated highly with other functioning measures; it also showed excellent test-retest reliability and internal consistency. CONCLUSIONS The FAST is a measure with sufficient validity and reliability, with potential for the use in international clinical trials and comparative studies.