Serious mental illness (SMI), including bipolar disorder or schizophrenia spectrum disorders, is associated with a twofold increased risk for comorbid physical illness, results of a new meta-analysis showed.
“Although treatment of physical and mental health remains siloed in many health services globally, the high prevalence of physical multimorbidity attests to the urgent need for integrated care models that address both physical and mental health outcomes in people with severe mental illness,” the authors, led by Sean Halstead, MD, of The University of Queensland Medical School in Brisbane, Australia, wrote.
The findings were published online in The Lancet Psychiatry.
Shorter Lifespan?
SMI is associated with reduced life expectancy, and experts speculate that additional chronic illnesses — whether physical or psychiatric — may underlie this association.
While previous research has paired SMI with comorbid physical illnesses, the researchers noted that this study is the first to focus on both physical and psychiatric multimorbidity in individuals with SMI.
The investigators conducted a meta-analysis of 82 observational studies comprising 1.6 million individuals with SMI and 13.2 million control subjects to determine the risk for physical or psychiatric multimorbidity.
Studies were included if participants were diagnosed with either a schizophrenia spectrum disorder or bipolar disorder, and the study assessed either physical multimorbidity (at least two physical health conditions) or psychiatric multimorbidity (at least three psychiatric conditions), including the initial SMI.
Investigators found that individuals with SMI had more than a twofold increased risk for physical multimorbidity than those without SMI (odds ratio [OR], 2.40; 95% CI, 1.57-3.65; P = .0009).
Physical multimorbidity, which included cardiovascular, endocrine, neurological rental, gastrointestinal, musculoskeletal, and infectious disorders, was prevalent at similar rates in both schizophrenia spectrum disorder and bipolar disorder.
The ratio of physical multimorbidity was about four times higher in younger populations with SMI (mean age ≤ 40; OR, 3.99; 95% CI, 1.43-11.10) than in older populations (mean age > 40; OR, 1.55; 95% CI, 0.96-2.51; subgroup differences, P = .0013).
In terms of absolute prevalence, 25% of those with SMI had a physical multimorbidity, and 14% had a psychiatric multimorbidity, which were primarily anxiety and substance use disorders.
Investigators speculated that physical multimorbidity in SMI could stem from side effects of psychotropic medications, which are known to cause rapid cardiometabolic changes, including weight gain. In addition, lifestyle factors or nonmodifiable risk factors could also contribute to physical multimorbidity.
The study’s limitations included its small sample sizes for subgroup analyses and insufficient analysis for significant covariates, including smoking rates and symptom severity.
“While health services and treatment guidelines often operate on the assumption that individuals have a single principal diagnosis, these results attest to the clinical complexity many people with severe mental illness face in relation to burden of chronic disease,” the investigators wrote. They added that a greater understanding of the epidemiological manifestations of multimorbidity in SMI is “imperative.”
There was no source of funding for this study. Dr. Halstead is supported by the Australian Research Training Program scholarship. Other disclosures were noted in the original article.
A version of this article appeared on Medscape.com .