Subjective quality of life among patients with schizophrenia spectrum disorder and patients with major depressive disorder

Background The goal of clinicians and healthcare workers providing treatment to patients with psychiatric disorders, has shifted over time from focusing on the symptoms alone towards functional improvement. In this study, we aimed to compare the subjective quality of life (QoL) among patients with schizophrenia spectrum disorders and major depressive disorder (MDD). Methods QoL scores were collected using 36-item Short Form Survey Instrument. QoL scores were compared between 203 outpatients with schizophrenia spectrum disorders and 185 outpatients with MDD using analysis of covariance. The Positive and Negative Syndrome Scale was administered to assess the severity of psychiatric symptoms among patients with schizophrenia and Personal Health Questionnaire-8 items was utilized to assess the severity of depressive symptoms among patients with MDD. The correlation coefficient (r) of socio-demographic factors and core psychiatric symptoms with QoL were analyzed using multiple linear regression. Results As compared to patients with MDD, patients with schizophrenia reported better health scores in all QoL subdomains, except for physical function (PF). Among patients with schizophrenia, old age was correlated with better mental health (MH, r = 0.35) and PF (r = 0.37). Compared to those of Chinese ethnicity, those of Malay, Indian and other ethnicity were correlated with worse PF (r = - 0.43 for Malays; r = - 0.30 for Indians and r = - 0.34 for other ethnicities). Longer duration of mental illness was correlated with worse MH (r = - 0.30), worse PF (r = - 0.38) and worse scores on role limitations due to physical health problems (RP, r = - 0.30). Among patients with MDD, older age was correlated with worse PF (r = - 0.33) and patients without comorbid physical illness reported less bodily pain (r = 0.45) and better general health (r = 0.34). Moreover, all psychiatric symptoms among patients with schizophrenia were negatively correlated with QoL, but the strength of the correlation was less than that between depressive symptoms and QoL among patients with MDD. Conclusion Patients with schizophrenia generally reported better QoL as compared to patients with MDD. The correlates of QoL differed between patients with schizophrenia and patients with MDD. This study adds to the understanding of QoL among patients with mental illnesses and may aid in better management of these patients with different psychiatric diagnoses.