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

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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.