Abstract
BACKGROUND: Schizophrenia places a great humanistic and financial burden to patients, families, and societies, and the burden is substantially impacted by comorbid conditions. This study aimed to estimate the lifetime prevalence of schizophrenia and to assess the health-related quality of life (HRQoL), work productivity, and indirect cost among schizophrenia patients with and without comorbidities (depressive symptoms, sleep disturbances, and anxiety problems). METHODS: This is a secondary analysis of existing data collected in 2019 from the Japan National Health and Wellness Survey. The schizophrenia patients were categorized based on their Patient Health Questionnaire-9 score, self-reported experience of sleep disturbances, and anxiety problems. The lifetime prevalence was estimated using the total number of diagnosed schizophrenia patients as the numerator and the total number of respondents as the denominator. The HRQoL was evaluated through the Short Form 12-Item (version 2) Health Survey and EuroQoL 5-dimensions scale. Work productivity and annual indirect costs were evaluated through the Work Productivity and Activity Impairment instrument and monthly wage rates. Multivariate analyses included the comparison of outcomes using generalized linear models. RESULTS: The study was conducted with 178 schizophrenia patients with an average age of 42.7 years old and an estimated lifetime prevalence of 0.59% (95% CI: 0.51%, 0.68%). Patients who experienced sleep disturbances, more severe depressive symptoms, and anxiety problems had lower HRQoL, higher levels of absenteeism, presenteeism, total work productivity and activity impairment, and almost twice more indirect costs, compared to those without these conditions. CONCLUSION: Comorbid conditions among patients with schizophrenia impact significantly on their quality of life, work productivity as well as indirect costs.