Measuring quality of life in patients with schizophrenia

Schizophrenia is a chronic disabling illness that affects about 1% of the population. It is a heterogenous disorder with variable aetiological, prognostic and treatment response patterns. Its course is generally long term, with acute psychotic exacerbations that may require hospitalisation. The cornerstone of clinical management is the use of antipsychotic (neuroleptic) medications. Although these are effective, they can cause adverse effects that may impact negatively on the functional status of the individual. Early studies of quality of life in schizophrenia were mainly concerned with the development of techniques to identify patients' needs in the community. Difficulties encountered in these studies included: lack of agreement on definition of quality of life; lack of appropriate integrative conceptual models; concerns about reliability of patients' self-reports about their quality of life; and the lack of standardised quality-of-life measures appropriate for schizophrenia. A number of disease-specific or generic scales have subsequently been used for measurement of quality of life in schizophrenia. The list of disease-specific scales is extensive; unfortunately, many of them were used only in a single study or their psychometric properties were not specified. Generic scales can be applied across various types and severity of illness, as well as in different health interventions across demographic and cultural groups. Medication costs in schizophrenia represent only a small fraction of the total cost of the illness. However, pharmacoeconomic studies have attracted much interest as a result of the high cost of newly introduced medications and of concern about the limitations of antipsychotic medications, particularly their adverse effects, as exemplified by the reintroduction of clozapine for the treatment of refractory schizophrenia. Few studies have combined quality-of-life measures with cost analysis in schizophrenia; a number of these have methodological shortcomings. Many studies are retrospective in nature, and in most the number and length of hospitalisations has been used as the parameter for cost analysis, which can introduce bias depending on the varying approaches to hospitalisation. We conclude that the following factors are important in choosing or developing a quality-of-life measure for schizophrenia: quality of life is a multidimensional concept that has to be reflected in its measurement; the scale has to be appropriate for the purpose as well as the population studied; measurement has to include patients' self-reports about their quality of life; measures should include only items that are relevant and expected to change; single-item global measures are useful only when combined with multidimensional measures; in developing new scales, psychometric properties have to be established as well as being field-tested.