Comorbidity in the American Population

As the years progress, comorbidity has become the norm in America, with 80% of Medicare spending targeted to patients with more than 4 chronic conditions. As spending grows exponentially, scientists and practitioners are trying to gain a better grasp on the effects of comorbidities on mortality rates, quality of life, and quality of healthcare.

Comorbidity is the presence of 2 or more illnesses/ diseases in a patient. Common overlapping conditions are cancer, diabetes, hypertension, cardiovascular illnesses, dementia, and mental conditions relating to depression, anxiety, eating disorders, and substance abuse. A person who is diagnosed with social anxiety and a depressive disorder is said to have comorbid depressive and anxiety disorders. 

Above is an array of mental illnesses and other disorders which are closely correlated and frequently can be present as comorbid conditions in patients. Credit: Neurological Disorders and Comorbidity

It is common for patients to have comorbidities, especially when relating to mental illnesses. As many patients are diagnosed with a regular illness, but also diagnosed with a mental illness in addition [or vise versa]. Studies have been conducted on the number of patients with comorbidities. In the US National Comorbidity study, 51% of patients who were diagnosed with major depression had at least one additional anxiety related disorder. Only 26% of patients diagnosed with depression had no other mental illnesses. There is a recurring pattern of anxiety being diagnosed in addition to other physical conditions.

The impacts of obesity on health also increases the number of comorbidities in the American population, with overlapping conditions such as type 2 diabetes, hypertension, coronary heart disease, gallbladder disease, and many more.

There are many reasons why comorbidities occur. Many illnesses are influenced or may be brought forth by similar behavioral habits (Ex: Smoking -> Lung Cancer and/ or Ischemic Heart Disease). Some conditions are triggered by other illnesses (Eating Disorders and Depression). Many conditions also have no correlation and develop independently. 

Regardless, the price of comorbidities in healthcare is taxing, and greatly increases risk factors of developing more health conditions. Patients are also found to have higher chances of mortality by Advanced Heart Failure if they have comorbid conditions. Sometimes treatment for these conditions fails to take into account of other underlying conditions, which affects how the patient’s body responds to certain medicines. Hence, professionals should continue considering the effects of certain medicines on patients with comorbid conditions.

In the face of viral infections and pandemics, underlying conditions do increase risks and rates of mortality, as seen with Covid-19- where immunocompromised patients or those with comorbid conditions are the most vulnerable.

Works Referenced

Ahluwalia, Sangeeta C, et al. “Impact of Comorbidity on Mortality among Older Persons with Advanced Heart Failure.” Journal of General Internal Medicine, Springer-Verlag, May 2012,

fichter, Brittany. “Comorbidity in Neurological Disorders.” Brittany F. Writes, 19 Feb. 2014,

He, Vincent Y.F., et al. “Long-Term Outcomes From Acute Rheumatic Fever and Rheumatic Heart Disease.” Circulation, 12 July 2016,

Maj, Mario. “’Psychiatric Comorbidity’: an Artefact of Current Diagnostic Systems?: The British Journal of Psychiatry.” Cambridge Core, Cambridge University Press, 2 Jan. 2018,

Park, Chanhyun, et al. “Comorbidity Status and Annual Total Medical Expenditures in U.S. Hypertensive Adults.” Ajpmonline, 2017,

Roca, M., et al. “Prevalence and Comorbidity of Common Mental Disorders in Primary Care.” Journal of Affective Disorders, Elsevier, 10 Apr. 2009,

Vaidyanathan, Uma, et al. “Patterns of Comorbidity among Mental Disorders: a Person-Centered Approach.” ScienceDirect, 6 Oct. 2010,

Valderas, Jose M, et al. Defining Comorbidity: Implications for Understanding Health and Health Services. 2009,

Published by N

A high school student who is passionate about life sciences!

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