Quality of life in mentally ill, physically ill and healthy individuals: The validation of the Greek version of the World Health Organization Quality of Life (WHOQOL-100) questionnaire

OBJECTIVE: The World Health Organization Quality of Life (WHOQOL-100) questionnaire is a generic quality of life (QoL) measurement tool used in various cultural and social settings and across different patient and healthy populations. The present study examines the psychometric properties of the Greek version, with an emphasis on the ability of the instrument to capture QoL differences between mentally ill, physically ill and healthy individuals. METHODS: A total of 425 Caucasian participants were tested, as to form 3 groups: (a) 124 psychiatric patients (schizophrenia n = 87, alcohol abuse/dependence n = 37), (b) 234 patients with physical illness (hypertension n = 139, cancer n = 95), and (c) 67 healthy control individuals. RESULTS: Confirmatory factor analysis was performed indicating that a four-factor model can provide an adequate instrument structure for the participating groups (GFI 0.92). Additionally, internal consistency of the instrument was shown to be acceptable, with Cronbach's α values ranging from 0.78 to 0.90 regarding the four -domain model, and from 0.40 to 0.90 regarding the six-domain one. Evidence based on Pearson's r and Independent samples t-test indicated satisfactory test/retest reliability, as well as good convergent validity tested with the General Health Questionnaire (GHQ-28) and the Life Satisfaction Inventory (LSI). Furthermore, using Independent samples t-test and one-way ANOVA, the instrument demonstrated good discriminatory ability between healthy, mentally ill and physically ill participants, as well as within the distinct patient groups of schizophrenic, alcohol dependent, hypertensive and cancer patients. Healthy individuals reported significantly higher QoL, particularly in the physical health domain and in the overall QoL/health facet. Mentally ill participants were distinctively differentiated from physically ill in several domains, with the greatest difference and reduction observed in the social relationships domain and in the overall QoL/health facet. Within the four distinct patient groups, alcohol abuse/dependence patients were found to report the most seriously compromised QoL in most domains, while hypertensive and cancer patients did not report extensive and significant differences at the domain level. However, significant differences between patient groups were observed at the facet level. For example, regarding the physical domain, physically ill participants reported more compromised scores in the pain/discomfort facet, while mentally ill participants in the facets of energy/fatigue, daily living activities and dependence on medication. CONCLUSION: The findings of the study indicate that the Greek version of WHOQOL-100 provided satisfactory psychometric properties supporting its use within general and pathological populations and in the context of national and crosscultural QoL measurement.