Quality of life in people with psychotic disorders : the relationship with global functioning and its predictors

Background: Psychotic disorders are some of the most disabling mental illnesses. Impairment in the global functioning of people living with a psychotic disorder is expected, as well as a decrease in their quality of life (QoL). The association between global functioning and QoL or health-related (HR) QoL has not been thoroughly investigated, however. Further, the pathway to achieve QoL/HRQoL for those living with a psychotic disorder has not been clearly established. This thesis aimed to address these knowledge gaps through four sequential studies. Methods: A systematic review of the literature assessing associations between global functioning and QoL in people with psychotic disorders was undertaken. Data from the 2010 Australian National Survey of Psychosis were then analysed, with the Assessment of Quality of Life (AQoL)-4D used to assess HRQoL. Spearman's rank correlation coefficients were used to assess associations between HRQoL and different aspects of functioning (global, independent, social) and social experiences (perceived loneliness and experienced stigma). Linear regression analyses were used to 1) determine aspects of functioning that jointly predict HRQoL; and with reference to novel theoretical models 2) establish predictors of HRQoL; and 3) ascertain contributors to the perception of loneliness. Following Baron and Kenny specifications, two mediation analyses were undertaken to establish the mediating role of global functioning and perception of loneliness in the causal pathway to HRQoL. Results: Moderate associations between higher global functioning and better QoL in people with psychotic disorders were consistently found, with QoL instruments affecting associations. Global and social functioning were found to jointly predict the HRQoL of participants in the survey. Furthermore, seven variables were established as meaningful predictors of HRQoL, perceived loneliness, negative symptoms, use of psychotropic medication, course of disorder, current housing, lifetime history of cardiovascular disease and chronic pain, with all except loneliness and chronic pain mediated through global functioning. The strongest predictor was perception of loneliness. Subsequently, nine contributors to loneliness were ascertained (social dysfunction, contact with friends, experienced stigma, diagnosis, depressive symptoms, anxiety, service utilisation in the last 12-months, lifetime arthritis and traumatic events in childhood). The effects on HRQoL of all, except service utilisation, were mediated through loneliness. Also mediated through loneliness were negative symptoms and use of psychotropic medication, previously known predictors of HRQoL. Between 23% and 49% of the variance in HRQoL was explained across the models. Conclusions: The importance of both global functioning and social relationships to the QoL/HRQoL of people with psychotic disorders was established, and they should thus be considered when evaluating the QoL/HRQoL of this population. The determination of several meaningful predictors of HRQoL, including loneliness, provides potential targets for interventions aimed at improving the HRQoL of this population. HRQoL should be considered an important outcome for people living with psychotic disorders in clinical and policy decision-making settings alike. Clinicians and policy makers should make improvement in the social aspects of the lives of people with psychotic disorders a priority alongside symptom remission and improvement of functioning.