Health-related quality of life in outpatients with schizophrenia: factors that determine changes over time.

Purpose: The objective of this study was to analyze the clinical factors associated with changes in HRQoL in outpatients with schizophrenia using both generic and condition-specific HRQoL scales.
Methods: Adult outpatients with schizophrenia at least 18 years of age who did not have an acute psychotic exacerbation in the 3 months prior to baseline were recruited. PANSS dimensions were calculated based on Lindenmayer et al.'s five factors. HRQoL data were assessed by patients using the Schizophrenia Quality of Life Scale (SQLS), the Short Form-36 (SF-36), and the EuroQol-5 Dimension (EQ-5D) questionnaires.
Results: Out of the 1345 patients included at baseline, 1196 (89%) were evaluated at 12 months. Regression models showed that the factor most consistently associated with HRQoL at endpoint was change in the PANSS negative symptoms score. A decrease in the PANSS negative symptoms score from baseline to 1 year was associated with a decrease in HRQoL during the same period. There were also significant associations of the change in PANSS excitatory factor with all the HRQoL scales except the SF-36 PCS. Female gender was associated with a decrease in all HRQoL ratings. There was also a relationship between years since onset and HRQoL. The longer the time since illness onset, the larger the decrease in HRQoL.
Conclusions: This study has found that, in outpatients with schizophrenia, changes in negative and excitement symptoms may have a greater an association with HRQoL than changes in positive, cognitive and depressive symptoms.