Development and psychometric properties of the World Health Organization Quality of Life Assessment Instrument (WHOQOL-100) in Portugal.

BACKGROUND At the beginning of the 1990s, the World Health Organization (WHO) developed a project in order to create a cross-cultural instrument of quality of life assessment: the World Health Organization Quality of Life (WHOQOL). PURPOSE This paper describes the development of the European Portuguese version of the WHOQOL-100, according to the methodology recommended by the WHO. METHOD Special attention is given to the qualitative pilot study, which led to the development of the Portuguese Facet [Political P], and to the empirical pilot study and the psychometric studies, based on the application of the Portuguese version of the instrument to a sample of 315 subjects from the general population and 289 patients. The assessment protocol also included the Beck Depression Inventory and the Brief Symptom Inventory. RESULTS The Portuguese version of WHOQOL-100 showed acceptable internal consistency (alpha range 0.84-0.94) and test-retest reliability in all domains (r range 0.67-0.86). Discriminant validity was significant for all domains, except in Spirituality. Convergent validity with the Beck Depression Inventory and the Brief Symptom Inventory was satisfactory for most domains. CONCLUSION The WHOQOL showed good psychometric characteristics, suggesting that the Portuguese version of WHOQOL is valid and reliable in the assessment of quality of life in Portugal.