Subjective and Objective Measures of Quality of Life Have Different Predictors for People with Schizophrenia

Abstract

This study investigated the relationship between subjective and objective quality of life and assessed predictors in people with schizophrenia. The study population consisted of 99 stabilized outpatients with schizophrenia (DSM-IV) who had been regularly receiving outpatient treatment at the Department of Psychiatry, The Tokushima University Hospital. Subjective and objective quality of life were estimated using the Schizophrenia Quality of Life Scale and the Quality of Life Scale, respectively. Psychiatric symptoms were also measured with the Brief Psychiatric Rating Scale and the Calgary Depression Scale for Schizophrenia. Scores on the Schizophrenia Quality of Life Scale Motivation and Energy scales significantly correlated with the Quality of Life Scale total scores –.40 (p <.001), and with the scores on Interpersonal Relations subscale –.42 (p <.001), Instrumental Role subscale –.28 (p = .005), Intrapsychic Foundations subscale –.39 (p <.001), and Common Objects and Activities subscale –.25 (p = .014). The Schizophrenia Quality of Life Scale Psychosocial scale significantly correlated with only the Quality of Life Scale total score –.20 (p = .05), and there was no significant correlation between the scores on the Schizophrenia Quality of Life Scale Symptoms and Side-effects scales and the Quality of Life Scale. Stepwise regression analyses showed that the Calgary Depression Scale for Schizophrenia score was the most important predictor of each scale of the Schizophrenia Quality of Life Scale, and the Brief Psychiatric Rating Scale Negative Symptoms score was the most important predictor of the Quality of Life Scale total score and each subscale. These results suggest that subjective and objective quality of life have different predictors and should be considered as separate and complementary outcome variables.