1. Introduction
Quality of life (QoL) among persons with schizophrenia and other serious mental illnesses (SMI) has become an important outcome assessment for both research and treatment in recent years. However, it remains unclear what factors best predict QoL in this population and a significant challenge for researchers has been the varied methods used to define and measure the broad concept. In an attempt to reduce some of this heterogeneity, research in this area has begun to distinguish between objective and subjective assessments of QoL, as these appear to represent distinct constructs. For instance, objective QoL has been operationalized by examining factors such as the frequency of social interactions, number of hours worked per week, or housing status. However, subjective QoL measurement, which addresses perceived life satisfaction, may be a particularly meaningful treatment goal in this population and is consistent with the recovery model, which emphasizes the lived experience of individuals with SMI.
To date, much of the research on life satisfaction in SMI has focused on its relationship with cognitive and clinical symptoms. In terms of cognition, some studies have reported significant correlations between life satisfaction and cognition, while others, including a meta-analysis by Tolman and Kurtz, have reported either no correlations or inverse correlations between life satisfaction and cognitive functioning. With regard to psychiatric symptomatology, current research has revealed variable relationships. For example, life satisfaction has been associated with psychiatric symptoms, such as depressive and negative symptomatology. However, Narvaez et al. reported that symptom reduction alone did not translate into improved life satisfaction.
Another proposed approach of operationally defining overall life satisfaction in schizophrenia has included examining the impact of disease-related or health-related factors on an individual’s perceived QoL, which is referred to as health-related quality of life (HRQoL). HRQoL is a particularly relevant outcome indicator for this population, given that individuals with schizophrenia and other SMIs experience significantly elevated rates of medical comorbidity and early mortality compared to the general population. Thus, the assessment of HRQoL has the benefit of incorporating a broader definition of physical/mental health and its impact on life satisfaction than other general life satisfaction measures, which often have limited coverage of physical health. Previous studies have demonstrated that individuals with schizophrenia and other SMIs report poorer HRQoL than people without SMI. HRQoL in this population has been consistently associated with psychiatric symptomatology, such as depression and general psychopathology.
The most widely used measure of HRQoL is the Short Form Health Survey (SF-36), which distinguishes between mental HRQoL (Mental Health Component Summary Scale (MHC)) and physical HRQoL (Physical Health Component Summary Scale (PHC)). However, few researchers in SMI have begun to examine the distinctions between physical and mental HRQoL. Notably, Meijer et al. reported recently that mental HRQoL, compared to physical HRQoL, was a stronger predictor of overall life satisfaction. In general, little is known about the distinction between mental and physical HRQoL or the relative determinants of each. Given that there are multiple methods for assessing QoL, which have been demonstrated to be distinct from one another, further research is needed to understand the unique determinants of the various QoL indicators.
The current study simultaneously examined three important aspects of life satisfaction for persons with schizophrenia and other SMIs: overall life satisfaction, mental HRQoL, and physical HRQoL. Specifically, the current study has two aims: (1) to evaluate the subjective concern with physical HRQoL relative to the concern with mental HRQoL and (2) to investigate the cognitive, clinical, and functional correlates of the three QoL indicators.