People with mental disorders and comorbid medical conditions have an 11-year reduction in life expectancy compared to the general population, according to a new study.
The findings from a national population-based cohort assessment in Denmark suggest it is actually patients having a combination of a mental disorder and coinciding conditions that significantly shorten their life expectancy—not them having just one of either. As global rates of mental-physical multimorbidity increases, the investigators stressed the need for improved preventive and risk-assessment measures for high-risk patients.
Led by Natalie C. Momen, PhD, of the National Centre for Register-based Research at the Aarhus University School of Business and Social Sciences, investigators from Denmark sought to analyze the population’s mortality associated with comorbidity across a spectrum of mental disorders and general medical conditions (GMCs).
Previous research show that people with mental disorders on average generally die earlier than those without. But as Momen and colleagues noted, interpretation into what causes that reduced life expectancy is sometimes unreported. A previous study found men diagnosed with substance use disorders have a 14.8-year mean reduced life expectancy from the general population—but while 5.4 years of this reduction is attributable to suicides and unintentional injuries, the remaining 9.4 years were due to general medical conditions including diabetes, cardiovascular or pulmonary disease.
“Other studies focusing on specific mental disorders have also reported that mortality rates from various GMCs are higher among people with mental disorders, although they did not report absolute measures like life expectancy,” they wrote. “The fact that a large part of the mortality gap in those with mental disorders is related to GMCs is not unexpected, given that people with mental disorders have an increased risk of developing comorbid conditions.”
The investigators’ cohort analysis included 5.95 million individuals born in Denmark from 1900-2015 who resided in the country at least at the start of follow-up, identified as either January 1, 2000 or their date of birth, whichever occurred later. They then used Danish health registries to identify people with mental disorders and GMCs, calculating mortality rate ratios (MRRs) and differences in life-years lost for persons with pairs of medical disorders and GMCs versus those with lone mental disorders, GMCs, or neither.
Their population was 50.2% female, with a median age of 32.0 years old at follow-up and 48.9 years old at the end of assessment. The most frequent mental disorders included the following:
Among the most frequent GMCs in the cohort population were the following:
Additionally, a proportion of the population was observed to have cancer (9.23%), diabetes (6.55%), or ischemic heart disease (8.34%), among other conditions.
Investigators observed a mean MRR of 5.90 (IQR, 3.80 – 7.30) for all 90 mental disorder-CMG category pairs prevalence compared with neither mental disorder nor GMC prevalence. Compared with those with only GMC, combination mental disorder-CMG was associated a mean 2.40 MRR (IQR, 1.90 – 2.71). And compared with those with only mental disorder, combination mental disorder-CMG was associated with a mean 2.61 MRR for males and 2.29 for females.
As the team noted, MRR for patients with lone metal disorder varied based on the specific condition—an eating disorder would result in a greater ratio than a mood disorder, for example.
Investigators observed that persons with both mood disorders and GMC had a reduced life expectancy for all 85 quantifiable pairs assessed versus the general population. Mean life-years lost were 11.35 years (IQR, 8.22 – 13.72). Investigators observed a continued decrease in life expectancy when controlling for age in their cohort.
Mental disorder comorbidity in people with GMCs was associated with a mean 5.54 life-years lost (IQR, 3.95 – 7.54). Conversely, GMC in people with mental disorders was associated with a mean 4.11 life-years lost (IQR, 2.06 – 5.94).
Again, investigators observed that type of mood disorder and GMC impacted the life-years lost averages; persons with both mood disorders and heart failure lost 8.16 years in life expectancy versus the general population, for example.
“We believe these estimates provide the most detailed assessments of the association with comorbid GMCs among people who have mental disorders,” they wrote.
The team noted several limitations to the study including the restricted range of assessed GMCs, as well as a broad definition of mental disorder-GMC pairings in the population cohort. “Here, scenarios do not cover the entire complex and transactional pathways that influence mental disorder-GMC temporal patterning,” they wrote.
Nonetheless, the team concluded their findings highlight the need for targeted intervention addressing comorbidity risk factors in persons with mental disorders including depression.
“We hope these estimates provide a foundation for future research aiming to improve life expectancy among people with comorbidity,” investigators wrote. “They highlight the need to optimize screening for GMCs among people with mental disorders so comorbidity can either be prevented or identified early and managed well.”
The study, “Mortality Associated With Mental Disorders and Comorbid General Medical Conditions,” was published online in JAMA Psychiatry.