The results come from a unique study, led by Dr Seena Fazel, at Oxford University, UK, which analyses long-term adverse outcomes - including conviction for a violent crime (such as homicide or bodily harm) premature death (before the age of 56), and death by suicide - between 1972 and 2009 in nearly 25,000 people in Sweden diagnosed with schizophrenia or related disorders.
For the first time, the researchers compared adverse outcomes in people with a diagnosis of schizophrenia to both the general population and to unaffected siblings, allowing them to account for risk factors within families (such as parental criminality or violence) which might be expected to affect the risk of suicide or violent behaviour in siblings.
Overall, the results show that within five years of diagnosis, around 1 in 50 men and women with schizophrenia (2.3% of men and 1.7% of women) died by suicide; around one in 10 (10.7%) of men and around one in 37 (2.7%) of women with schizophrenia were convicted of a violent offence within five years of diagnosis. Overall, men and women with schizophrenia were eight times more likely to die prematurely than the general population. Analysing the changing rate of adverse outcomes across the study period (1972 - 2009), the researchers found that the risk of premature death, suicide, and conviction for a violent offence has increased for men and women with schizophrenia in the last 38 years, compared with both the general population, and their unaffected siblings.
By tracking the number of nights spent in hospital by people with schizophrenia during the study period, the study shows that these increased rates of adverse outcomes appear to be associated with decreasing levels of inpatient care for these patients, although the study does not provide any evidence for a causal connection between decreasing inpatient care and adverse outcomes.
The researchers also analysed risk factors for adverse outcomes in both people with schizophrenia, the general population, and unaffected siblings. Across all three groups, the risk factors for violence and premature death were broadly similar, and included drug use disorders, criminality, and self-harm, all before diagnosis - suggesting that improved strategies to address these risk factors have the potential to reduce violence and premature deaths across the population, and not just in those with schizophrenia.
According to Dr Fazel, "In recent years, there has been a lot of focus on primary prevention of schizophrenia - preventing people from getting ill. While primary prevention is clearly essential and may be some decades away, our study highlights the crucial importance of secondary prevention - treating and managing the risks of adverse outcomes, such as self-harm or violent behaviour, in patients. Risks of these adverse outcomes relative to others in society appear to be increasing in recent decades, suggesting that there is still much work to be done in developing new treatments and mitigating risks of adverse outcomes in people with schizophrenia."
Dr Eric Elbogen and Sally Johnson, at the University of North Carolina-Chapel Hill School of Medicine, USA, write in a linked Comment that, "One of the unique aspects of this study—that violence and suicide were analysed simultaneously—has an important implication for how we as a society perceive people with mental illness. News coverage of schizophrenia and other psychiatric disorders often focuses on violence and crime. Much less attention is paid to suicide and self-harm in people with severe mental illnesses." However, they add that, "Importantly, we should remember that, when reporting about the intricate links between schizophrenia and these adverse outcomes, most people with schizophrenia and related disorders are neither violent nor suicidal."
Despite the need to ensure people with schizophrenia are provided help to reduce their risks of suicide, violence, or premature death, researchers reporting findings also bear the burden of ensuring that most people with schizophrenia and related disorders, who are not violent, are not left to contend with stigma and discrimination. Policy makers, researchers, and clinicians need to remember the importance of appropriately weighing up the issue of schizophrenia relative to the myriad of other factors that contribute to increased risk of violence and suicide."