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.

Predictors of subjective and objective quality of life in outpatients with schizophrenia

“…7 Other similar studies including our own also support the association of depressive symptom with subjective QOL. [9][10][11] In the present study, emotional discomfort and positive factor were correlated with psychosocial scale scores of SQLS, and stepwise regression showed that emotional discomfort predicted the psychosocial score. Emotional discomfort, negative factor and positive factor were correlated with motivation/ energy scores of SQLS, and stepwise regression showed that emotional discomfort predicted the motivation/energy scale score.…”

“…The present results are consistent with those reported by Tomotake et al and Aki et al, who assessed subjective QOL and depressive symptoms with SQLS and the Calgary Depression Scale for Schizophrenia, respectively. 10,11 In the current study, drug-induced extrapyramidal symptoms, cognitive factor, and positive factor were correlated with symptoms/side-effects scale scores of SQLS, and stepwise regression showed that druginduced extrapyramidal symptoms predicted the symptoms/side-effects scale score. The present result suggests that the extrapyramidal symptom is a factor negatively influencing subjective QOL.…”

“…The present results are consistent with those reported by Tomotake et al and Aki et al, who assessed objective QOL and negative symptoms using QLS and BPRS, respectively. 10,11 Considering that QLS was originally designed to assess deficit symptoms and the dysfunctions related to them, 29 the correlation between negative symptoms and QLS scores seems to be reasonable.…”

“…Several studies including our own have suggested that depressive mood may be the most important determinant for subjective QOL. [6][7][8][9][10][11] Other studies reported that positive symptoms 12 or akathisia symptoms as well as the total severity of psychopathology 1 predicted subjective QOL.…”

“…In some studies, the severity of negative symptoms 7,10,11,13 or the presence of tardive dyskinesia 14 was reported to be associated with a poor objective QOL. Levels of insight into the illness showed no significant relationship with QOL levels.…”