Subjective and objective quality of life in schizophrenia
Introduction
Subjective well-being and quality of life (QOL) are increasingly being recognized as important treatment outcomes in patients with schizophrenia (Hofer et al., 2005b, Ruggeri et al., 2005). Until recently, treatments for schizophrenia have focused mainly on reducing positive symptoms, often leaving patients with numerous residual difficulties, including negative symptoms and impairment in cognition, everyday living skills, and social/occupational functioning. More comprehensive treatments are needed, and it makes sense that improved QOL should be a primary treatment goal. However, the predictors of QOL in schizophrenia are not well understood. Although no universal definition of QOL exists, the construct usually includes subjective well-being and objective mental and physical functioning indicators (Lehman, 1983b, Norman et al., 2000, Bow-Thomas et al., 1999, Voruganti et al., 1998, Russo et al., 1997, Lambert and Naber, 2004). Subjective QOL focuses on life satisfaction, whereas “objective” QOL focuses on participation in activities and interpersonal relationships. Although some conceptualizations hold that QOL is always purely subjective, we have adopted Lehman's use of the terms “subjective” and “objective” QOL (Lehman, 1988) as a way to differentiate subjective life satisfaction from observable QOL indicators. Although Harvey and colleagues suggest that patients' self-report of functional capacity may be problematic (Harvey et al., 2007), other research demonstrates that self-report measures of QOL are more valid than clinician-report QOL measures, and that QOL can be rated accurately and consistently by patients (Voruganti et al., 1998, Becchi et al., 2004).
Lower everyday functioning capacity and greater severity of positive, negative, and depressive symptoms have been associated with worse QOL (Hofer et al., 2005b, Norman et al., 2000, Palmer et al., 2002, Sciolla et al., 2003, Corrigan and Buican, 1995, Jin et al., 2001, Ruggeri et al., 2005, Twamley et al., 2002). Although such psychiatric symptoms have been associated with subjective measures of QOL (Hofer et al., 2005b, Ruggeri et al., 2005, Norman et al., 2000, Corrigan and Buican, 1995), symptom reductions alone often do not result in meaningful improvements in QOL because other problems remain (e.g., difficulty with everyday functioning, lack of social contacts, unemployment, and stigmatization).
Cognitive abilities are associated with functional capacity and community outcomes (Evans et al., 2003, Twamley et al., 2002, Patterson et al., 2001, Green and Nuechterlein, 1999, Green, 1996, Green et al., 2000), and may also affect life satisfaction. Poorer cognitive performance and self-reported functional status (e.g., unmarried, lower social functioning, smaller social support network) are correlated with lower subjective QOL (Corrigan and Buican, 1995, Norman et al., 2000, Lehman, 1983a). On the other hand, better cognitive abilities may translate into better insight, more depression, and lower subjective well-being. Demographic and clinical characteristics also influence subjective QOL, with women and those with less education, longer illness duration, and higher antipsychotic dosages reporting greater life satisfaction (Hofer et al., 2005b, Ruggeri et al., 2005, Corrigan and Buican, 1995). The link between greater illness severity and better subjective QOL may be due partially to the effects of impaired insight (Karow and Pajonc, 2006).
Patients' self-reports of everyday functioning and activities have also been used to assess objective QOL and are distinct from self-reports of overall life satisfaction (Lehman, 1983b). Indicators of objective QOL include living situation, marital status, employment status, driving status, and involvement in social activities. Generally, patients with less severe psychiatric symptoms and better cognitive performance report better outcomes on objective QOL indicators (Hofer et al., 2005b, Palmer et al., 2002, Sciolla et al., 2003, Jin et al., 2001, Ruggeri et al., 2005). Performance-based functional capacity also has been found to predict objective QOL, particularly in terms of driving and living independence (Palmer et al., 2002, Twamley et al., 2002).
The present study aimed to identify predictors of subjective and objective QOL in outpatients with schizophrenia and schizoaffective disorder. To our knowledge, no studies have simultaneously examined the clinical, functional, and cognitive predictors of both subjective and objective QOL in this population. In the current study, we used an extensive interview measure that evaluates subjective and objective QOL separately (the Quality of Life Interview; Lehman, 1988). Furthermore, unlike previous work, we used a performance-based measure of functional capacity (the UCSD Performance-Based Skills Assessment; Patterson et al., 2001) because many individuals with schizophrenia are not accurate raters of their own community functioning abilities (Bowie et al., 2007). This instrument goes beyond asking about activity participation (i.e., objective QOL) by having the examinee perform tasks necessary for independent living (e.g., grocery shopping, paying a bill, and planning a bus route). We also administered a comprehensive neuropsychological battery, rather than relying on cognitive screening measures. Our hypotheses, guided by previously published results, were that 1) greater subjective QOL would be associated with less severe negative and depressive symptoms, better functional status on objective QOL indicators, and greater performance-based functional capacity, and 2) better objective QOL would be associated with less severe negative and depressive symptoms, better cognitive performance, and greater functional capacity (see Fig. 1).
Section snippets
Participants
Participants included 88 outpatients with DSM-IV (American Psychiatric Association, 1994) diagnoses of schizophrenia or schizoaffective disorder. Diagnoses were made by the treating psychiatrist and confirmed via diagnostic chart reviews by trained research staff using DSM-IV criteria. Individuals with substance abuse or dependence within the past month and those with dementia, loss of consciousness > 30 min, or other neurological disorders were excluded from the study.
Procedure
All subjects were enrolled
Results
Sample characteristics are reported in Table 1. Most participants were middle-aged, male, Caucasian, and had a high school education. Most participants were unemployed (94%) and had never been married (56%); 35% were divorced, separated, or widowed, and 9% were currently married. Many participants (49%) lived with a roommate, family member, or romantic partner, 33% lived alone, 14% lived in a board-and-care facility or assisted living facility, and 4% were homeless. On average, the participants
Discussion
The main finding of this study is that psychiatric symptoms are the best independent predictors of subjective and objective QOL in schizophrenia. The single best predictor of subjective QOL was the severity of depressive symptoms, whereas the single best predictor of objective QOL was the severity of negative symptoms. It appears that depressive symptoms and better cognitive functioning are associated with worse life satisfaction, whereas negative symptoms limit participation in daily
Role of funding source
Funding for this study was provided by NIMH Grants MH066011 and MH066248 and by a grant from NARSAD; neither the NIMH nor NARSAD had further roles in study design; in the collection, analysis and interpretation of data; in the writing of the report; and in the decision to submit the paper for publication.
Contributors
JMN and EWT designed this study, conducted the statistical analyses, and wrote the first draft of the manuscript. EWT designed the parent studies from which the data were drawn. RKH and TLP assisted with the planning of the analyses and with writing the manuscript. CLM assisted with the analyses and with writing the final manuscript. All authors contributed to and have approved the final manuscript.
Conflict of interest
All authors declare that they have no conflicts of interest.
Acknowledgements
We thank Dr. Dilip Jeste for reviewing the manuscript and Cynthia Zurhellen for her assistance with the preparation of the manuscript.
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The authors wish it to be known that, in their opinion, the first two authors should be regarded as joint First Authors.