Symptoms of schizophrenia fall into three categories (positive, negative and cognitive symptoms), which probably impact differently on patient's health-related quality of life (HRQoL). The present study aimed to explore HRQoL in patients with prominent negative symptoms.
In the 323 patients with prominent negative symptoms included in a multicenter Phase II trial investigating the safety and efficacy of bitopertin, HRQoL was assessed using the Schizophrenia Quality of Life Scale (SQLS), symptoms severity using the Positive and Negative Syndrome Scale and functioning using the Personal and Social Performance Scale. SQLS measurement properties were assessed; HRQoL was compared between treatment arms, and relationships between HRQoL, symptoms and functioning at baseline were explored.
Both SQLS scores (Vitality/Cognition and Psychosocial Feelings) demonstrated good test-retest (ICC = 0.77 and 0.74) and internal consistency reliability (Cronbach's α = 0.86 and 0.93). Clinical validity with regard to schizophrenia severity and ability to detect change in severity of symptoms of schizophrenia were satisfactory. The SQLS structure was not formally disconfirmed. No statistically significant difference was observed between treatment arms. Negative symptoms were more strongly associated with functioning than positive symptoms. Functioning and Anxiety/Depression were strongly related to both SQLS domains.
Overall, SQLS measurement properties were supported in these patients with prominent negative symptoms of schizophrenia. The impact of negative symptoms on functioning and HRQoL suggests that improving these symptoms will be a meaningful benefit in this population of patients.