Validation of the WHO Quality of Life assessment instrument (WHOQOL-100) in a population of Dutch adult psychiatric outpatients.

Abstract

BACKGROUND: Research concerning the psychometric properties of the WHO Quality of Life Assessment Instrument (WHOQOL-100) in general populations of psychiatric outpatients has not been performed systematically. AIMS: To examine the content validity, construct validity, and reliability of the WHOQOL-100 in a general population of Dutch adult psychiatric outpatients. METHOD: A total of 533 psychiatric outpatients entered the study (438 randomly selected, 85 internally referred). Participants completed self-administered questionnaires for measuring quality of life (WHOQOL-100), psychopathological symptoms (SCL-90), and perceived social support (PSSS). In addition, they underwent two semi-structured interviews in order to obtain Axis-I and Axis-II diagnoses, according to DSM-IV. RESULTS: The drop-out percentage was low (7.1%). Of the 24 facets of the WHOQOL-100, 22 had a good distribution of scores, leaving out the facets physical environment and transport. Exploratory factor analysis revealed a four-factor structure, which was similar to earlier findings in patients with specific somatic diseases and depressive disorders. Various-a priori expected-positive and negative correlations were found between facets and domains of the WHOQOL-100, and dimensions of the SCL-90 and the PSSS-score, indicating good construct validity of the WHOQOL-100. The internal consistency of all facets and the four domains of the WHOQOL-100 was good (Cronbach's alpha's ranging from 0.62 to 0.93 and 0.64 to 0.84, respectively). Sparse and relatively low correlations were found between demographic characteristics (age and sex) and WHOQOL-100 scores. CONCLUSIONS: Content validity, construct validity, and reliability of the WHOQOL-100 in a population of adult Dutch psychiatric outpatients are good. The WHOQOL-100 appears to be a suitable instrument for measuring quality of life in adult psychiatric outpatients.