CLINICAL HANDBOOK OF SCHIZOPHRENIA

586 VIII. SPECIAL TOPICSthe quality-of-life scale questions becomes increasingly unlikely. However, research hasnot yet established the maximum symptom level to gain valid responses to quality-of-lifequestions, and the exact level may vary among individuals.The decision on which measure to use therefore depends on striking a balanceamong factors such as clinical time spent administering the instrument, practicalities relatedto ways of collecting the information (e.g., whether through face-to-face interviews,postal questionnaires, etc.), and psychometric properties of the instrument. The purposeof data collection should also be considered. If the measure is used to help clinicians in individualpatient care, a detailed measure may be needed to provide comprehensive informationon areas of dissatisfaction in the patient’s life that need to be addressed. On theother hand, if it is used to evaluate a service at a group level, then a shorter measure withgood psychometric properties may be more appropriate. A further criterion for selectingan instrument may be the availability of data to compare results. With respect to patientswith schizophrenia, various studies providing such data have been published using theQLS, QLI, LQOLP, MANSA and WHO Quality of Life Instrument—Brief (WHOQOL),and these scales have become established in schizophrenia research.ASSOCIATION WITH OTHER CONSTRUCTSThere is a tendency in psychiatry to use several instruments to describe the subjectiveexperience of patients with schizophrenia. While subjective quality of life reflects thepatient’s appraisal of the current life, self-ratings of needs and symptoms, as well as treatmentsatisfaction, are also used as research criteria to assess the outcomes of interventions,and are intended to assess distinct constructs. Is subjective quality-of-life independentof other constructs reflecting subjective experience, and should it be measured alongwith other constructs in the same study? Evidence indicates moderate to strong correlationsbetween subjective quality of life and ratings of symptoms, needs, and treatmentsatisfaction, with correlations ranging from .5 to .7 (Fakhoury, Kaiser, Röder-Wanner, &Priebe, 2002; Priebe, Kaiser, Huxley, Röder-Wanner, & Rudolph, 1998). A single subjectiveappraisal factor—reflecting negative subjective quality of life, more symptoms, andmore needs—explained 48–69% of the variance of all these patient-rated outcomes(Fakhoury et al., 2002; Priebe, Kaiser, et al., 1998). All this indicates that subjective criteriaare all interrelated and do not really capture distinct constructs. Thus, scales to assessseveral of these constructs should not be used as outcome criteria, unless a specific hypothesisjustifies the use of separate scales to assess patient-rated outcomes.Research also suggests a significant association between subjective quality of life andthe Antonovsky’s Sense of Coherence instrument. Sense of Coherence measures the personalorientation toward life that determines one’s health experience. Individuals with astrong sense of coherence believe that the world around them is structured, explicable,and predictable; that the resources needed to meet the demands of the world are availableto them; and that these demands are worthy of investment. There are three domainswithin the construct: comprehensibility, manageability, and meaningfulness. In a sampleof patients with schizophrenia it was found to be significantly associated with quality oflife. Increased Sense of Coherence score over time was found to be significantly associatedwith improvements in overall subjective quality of life (Bengtsson-Tops & Hansson,2001). Finally, a significant positive association between psychosocial functioning andsubjective quality of life in patients with schizophrenia has also been reported. This associationwas moderated by the executive functioning of the patient, independent of patientpsychopathology, suggesting the need to incorporate executive capacity in models ofquality of life (Brekke, Kohrt, & Green, 2001).