Impact of Negative Symptoms on Quality of Life in Patients with Schizophrenia

Abstract

Objectives: The present study analyses the impact and influence of negative symptoms on quality of life (QoL). Methods: The W-SOHO study is a three year follow-up study on the outpatient care of schizophrenia that included 17,384 patients from 37 countries. Patients were recruited in W-SOHO by their treating psychiatrists when starting or changing antipsychotic medication. Evaluation was conducted during the normal course of care and was scheduled every six months after the baseline visit. The Clinical Global Impressions Severity Scale - Schizophrenia version (CGI-SCH) was used to assess symptom severity across overall, positive, negative, depressive and cognitive subdomains. Quality of life (QoL) was assessed using the EuroQOL 5-D questionnaire. Pearson correlation coefficients (PCC) were used to analyze the relationship between continuous variables. A mixed model with repeated measures (MMRM) was used to analyze the factors associated with quality of life during follow-up. Results: Quality of life at baseline was more highly correlated with negative symptoms than with positive symptoms (PCC -0.25 for positive symptoms and -0.29 for negative symptoms; p<0.001). Improvement in negative symptoms was highly correlated to improvement in QoL (PCC 0.33; p<0.0001). The regression model analysing the influence of both positive and negative symptoms on QoL at baseline was confirmative and showed a greater beta coefficient (higher influence) for negative symptoms compared with positive symptoms [(3.9 (se 0.14) versus 2.9 (se 0.13)]. Another model found that patients with greater negative symptoms at baseline experienced lower improvement in QoL (beta coefficient -0.81; se 0.11; p<0.001). Conclusions: In patients with schizophrenia negative symptoms seem to have a larger influence onself-perceived QoL than positive symptoms. Improvement in negative symptoms is highly associated with improvements in QoL.