Objective: This study evaluated a population of outpatients with stable schizophrenia to analyze if relationships between patterns of symptomatology and quality of life (QOL) change during the time course of illness.
Methods: We recruited 168 outpatients with stable schizophrenia, and we further divided our sample into 3 groups of patients (<or=36, 37-72, and >72 months of illness). Psychiatric assessment included the Quality of Life Scale, the Positive and Negative Syndrome Scale, the Calgary Depression Scale for Schizophrenia, and the Clinical Global Impression-Severity Scale. All clinical variables significantly related to Quality of Life Scale scores were subsequently analyzed using a multiple stepwise regression to assess their independent contribution to QOL in the 3 patient groups.
Results: Quality of life and symptoms profiles were similar among patient groups. After controlling for potentially confounding variables, multiple regression revealed that depressive symptoms appeared to have a stronger relationship with QOL during the early 3-year course of the illness. In the period between 4 and 6 years of illness, negative symptoms were the most reliable predictors of QOL. After the 6-year course of illness, negative symptoms remained the most reliable predictors of QOL, together with severity of illness, whereas positive and depressive symptoms had a minor role.
Conclusions: Despite similar QOL and symptoms profiles, these findings suggested that relationships among patterns of symptomatology and QOL change during the course of schizophrenia.