BACKGROUND: An operational definition of serious mental illness (SMI) with well-defined inclusion criteria allows the identification of the most vulnerable individuals and secures resources to meet their needs and develop social programs for their treatment, rehabilitation, and recovery. In addition, the contents of a clinical construct such as SMI have an impact on both the development and the clinical application of the research results. However, currently, different ways of operationalizing the definition of SMI coexist. AIMS: The aim of this review was to explore whether unanimity exists in the operationalization of SMI definitions in quality-of-life interventions research. METHODS: A review of the literature based on searches of the MEDLINE and PsycINFO databases was conducted. Intervention studies were selected in which quality of life was the outcome variable and adults with SMI were the subject population. RESULTS: A wide range of definition of SMI is used in the scientific literature. CONCLUSIONS: There is a lack of unanimity in the variables considered necessary to identify SMI. The scientific literature uses different approaches to operationalize SMI, and these approaches vary considerably among studies. Caution is required when interpreting quality-of-life research that includes individuals labeled with SMI. It is necessary to reach a consensus on the criteria for applying the SMI label to ensure its content validity.
Keywords: mental disorders; quality of life; research methodology; serious mental illness; severe mental illness.