Investigating Somatic Multimorbidity in People with Mental Disorders Using Innovative Metrics and National Register-based Data

Despite the strong evidence on common occurrence of physical health conditions and their profound negative impact on survival in people with mental disorders, existing research has focused predominantly on the presence of single, distinct physical health conditions in these people. Somatic multimorbidity, denoting the coexistence of two or more chronic physical health conditions, remains incompletely described and understood in people with mental disorders. Furthermore, while it is known that the staggeringly lower life expectancy in people with mental disorders is explained by natural causes of death, the precise contributions of somatic multimorbidity to premature mortality have not been studied systematically. A major impediment in furthering knowledge is the prevailing methodology, consisting of solely counting of the number of physical health conditions, which is inherently unable to reveal the complex nature of somatic multimorbidity. The focus of SOMULTIMATE is to apply novel metrics on Danish national, register-based data that will allow to better capture the true burden of somatic multimorbidity in people with mental disorders. By considering the entire spectrum of mental disorders, SOMULTIMATE will provide the most comprehensive estimates (i) of the extent and patterns of somatic multimorbidity and (ii) of the impact of somatic multimorbidity on mortality in these conditions. This would facilitate the identification of the most common somatic multimorbidity, including in a wide array of so far overlooked mental disorders, and potentially inform screening targets for physical health conditions in various settings. Unravelling the precise contributions of somatic multimorbidity to premature mortality would then provide actionable targets to reduce the life expectancy gap. In addition, the methodological advances introduced by SOMULTIMATE would be directly applicable in diverse areas of medical research.