The study, published in PLOS Medicine, included national registers in Sweden to investigate more than one million patients who had diagnoses of chronic respiratory disease, cardiovascular disease, and diabetes. More than a quarter (25-32%) of people in the analysis had a co-occurring lifetime diagnosis of any psychiatric disorder.
Non-communicable diseases, such as diabetes and heart disease are a global public health challenge accounting for an estimated 40 million excess deaths annually.
Professor Seena Fazel, Department of Psychiatry, University of Oxford, said:
'This adds to the emerging evidence that improving assessment, treatment, and follow-up of people with comorbid psychiatric disorders will reduce mortality and suicide risk in people with chronic non-communicable diseases.'
Within five years of diagnosis, at least 7% of the people included in the study had died from any cause and 0.3% had died from suicide. Comorbid (two or more diseases in a patient) psychiatric disorders were associated with higher all-cause mortality (15.4%-21.1% over five years) when compared to those without such conditions (5.5%-9.1%).
When the researchers compared each patient with an unaffected sibling, who did not have the chronic health condition, so as to account for risk factors shared within families, such as early environment and genes, psychiatric comorbidity remained consistently associated with elevated rates of premature mortality and suicide. Risks ranged by psychiatric diagnosis; for instance, mortality risks were elevated by up to nine times in those with comorbid substance use disorder compared to unaffected siblings, and by up to seven times in those with comorbid depression.
One study limitation is that the use of population-based registries to identify patients meant that psychiatric comorbidities were diagnosed in outpatient and hospital settings and those with less severe psychiatric disorders could be missed.
Overall the findings point towards better integration of services for chronic physical, mental health and substance use services, and underscore the importance or primary care in the early diagnosis and treatment of psychiatric disorders.