Quality of life assessment in individuals with schizophrenia: a COSMIN-based systematic review of S-QoL41 and S-QoL18 incorporating neurobiological support

Abstract

Summary Background Quality of life is a key outcome in schizophrenia, requiring valid patient-reported outcome measures. We evaluated Schizophrenia Quality of Life (S-QoL) instruments. Methods We searched PubMed, PsycINFO, and Web of Science from inception to Dec 10, 2025. Measurement properties were assessed using the COnsensus-based Standards for the selection of health Measurement INstruments (COSMIN) guidelines and Risk of Bias checklist, and evidence quality was graded using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach. Heterogeneity was addressed through COSMIN-based best-evidence synthesis. Neuroimaging studies were reviewed to contextualise the neurobiological basis of S-QoL domains. This review is registered with PROSPERO, CRD420261287006. Findings Fourteen studies demonstrated sufficient validity (content, structural, and construct), internal consistency, and responsiveness of S-QoL instruments. Reliability was supported for S-QoL41 and S-QoL18, but limited for S-QoL-MCAT. Evidence for cross-cultural validity and measurement invariance ranged from very low to moderate certainty, while evidence for measurement error was scarce. Neuroimaging findings supported the construct coherence of S-QoL domains. Interpretation S-QoL41, S-QoL18, and S-QoL-MCAT demonstrate robust psychometric properties and are suitable for clinical research and practice. S-QoL18 offers the best balance between psychometric performance and feasibility. Further research should address cross-cultural validity, measurement error, and thresholds for individual-level change. Funding There was no specific funding source for this research.