Objective: To determine if aggression, hallucinations or delusions, and depression contribute to excess mortality risk observed in individuals with serious mental illness (SMI).
Methods: We identified SMI cases (schizophrenia, schizoaffective and bipolar disorder) aged≥15years in a large secondary mental healthcare case register linked to national mortality tracing. We modelled the effect of specific symptoms (HoNOS subscales) on all-cause mortality using Cox regression.
Results: We identified 6880 SMI cases (242 deaths) occurring 2007-2010. Bipolar disorder was associated with reduced mortality risk compared to schizophrenia (HR 0.7; 95% CI 0.4-0.96; p=0.028). Mortality was not significantly associated with hallucinations and delusions or overactive-aggressive behaviour, but was associated with physical illness/disability. There was a positive association between mortality and subclinical depression among individuals with schizophrenia (HR 1.5; 1.1-2.2; p=0.019) but a negative association with subclinical and more severe depression among those with schizoaffective disorder (HR 0.1; 0.02-0.4; p=0.001 and 0.3; 0.1-0.8; p=0.021, respectively).
Conclusions: The recognised increased risk of mortality in SMI did not appear to be influenced by severity of hallucinations, delusions, or overactive-aggressive behaviour. Physical illness and lifestyle may need to be addressed and the relationship between depression and mortality requires further investigation.
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