Structural equation modeling (SEM) has been widely used in psychology and sociology for testing validity of measurement instruments. However, this statistical technique has so far played minor role in quality-of-life research. The main objective of this paper is to demonstrate the potential of SEM for constructing and testing the validity of a Subjective Well-being under Neuroleptics (SWN) index for patients with schizophrenia. For these purposes, data from the GEO study (Gesundheitsökonomische Evaluation von Olanzapin in Deutschland; Health economics study of olanzapine in the treatment of schizophrenia in Germany) were used. The GEO is a prospective, comparative, noninterventional, observational study. A total of 646 participants treated with either olanzapine (n = 416) or haloperidol (n = 230) were enrolled in the study; 360 patients were available for factor analyses. The short (20-item) form of the SWN scale was administered to assess patients' perspectives on their quality of life. The structural equation models (SEMs) were then applied to construct 5- and 10-item indexes based on SWN. The data indicate that the 5-item index is the most time-saving approach for evaluating perceptions of well-being (and thus, quality of life) among patients with schizophrenia. The application of SEM showed no appreciable loss of validity of this index.
