Comorbidity refers to having two or more unrelated medical conditions or diseases at the same time. A comorbidity is a medical condition or disease that occurs concomitantly with another primary condition or disease, but which is unrelated to it. For example, obesity and depression are comorbid, but so are high blood pressure and pneumonia or COPD, chronic obstructive pulmonary disease, and COVID-19 or cancer and COVID-19. Comorbid conditions are known to raise the risks for complications and increase fatality rates, especially in high-risk categories such as those over 65.
COVID-19 comorbidities increase the risks for complications such as tissue and organ damage, including damage to the heart muscle, kidney damage, liver damage and lung damage, but also respiratory distress and poorer outcomes. But what are the top comorbidities in COVID-19? Here are the most common comorbidities known to occur in COVID-19 which increase the risks for complications and unfavorable outcomes:
(1) High blood pressure
Formally called hypertension, high blood pressure represents one of the top comorbidities in COVID-19. In a report from February 7, 2020 documenting the clinical characteristics of 138 hospitalized patients with 2019 novel Coronavirus-infected pneumonia in Wuhan, China, the Journal of the American Medical Association (JAMA) indicated high blood pressure as comorbidity in 58% of COVID-19 patients who required ICU care. In another report on the cardiovascular implications of fatal outcomes of 187 patients with confirmed Coronavirus disease 2019, 66 (35.3%) had underlying cardiovascular diseases, including hypertension, coronary heart disease, and cardiomyopathy, and 52 (27.8%) exhibited myocardial injury, or injury to the heart muscle that can predispose to higher risk of death.
It would appear at this point in time that diabetes is the second most common comorbidity in COVID-19 after high blood pressure. In the same report from the Journal of the American Medical Association (JAMA), diabetes was identified as comorbidity in 22.2% of all COVID-19 patients who required ICU care. Numbers were even higher in other reports and diabetes as a comorbidity in COVID-19 increases risks of complications. Research shows diabetics are at greater risk for complication from viral infections in general, whether it’s the flu or COVID-19. In a study from February 24, 2020, JAMA reports a higher case-fatality rate in COVID-19 patients with comorbidities, with diabetes having a case-fatality rate of 7.3%, second to cardiovascular disease at 10.5%. The study documented 44 672 confirmed COVID-19 cases from the Chinese Center for Disease Control and Prevention.
(3) Cardiovascular disease
Cardiovascular disease and more serious heart conditions remain one of the top comorbidities in COVID-19. Serious cardiovascular conditions such as heart failure, coronary artery disease, cardiomyopathy (diseases of the heart muscle), congenital heart disease and more accounted for 25% of COVID-19 cases that required ICU care in a report from February 7, 2020 documenting the clinical characteristics of 138 hospitalized patients with 2019 novel Coronavirus-infected pneumonia in Wuhan, China. In another JAMA summary of a report of 72 314 cases from the Chinese Center for Disease Control and Prevention, cardiovascular disease accounted for 10.5% of all case-fatality rates.
Serious cardiovascular disease represents an important risk factor for complications in COVID-19. COVID-19 patients with serious cardiovascular disease are more at risk for damage to the heart muscle and related side effects, including higher death rates. Damage to the heart muscle in COVID-19 can be caused directly by the virus infecting heart muscle cells, or indirectly by immune system involvement and associated systemic inflammation, but also hypoxia due to lung and other tissue damage which causes less oxygen to be delivered to body tissues such as the heart and other mechanisms.
(4) Blood disorders
According to the CDC, blood disorders such as sickle cell disease, thalassemias or blood clotting disorders, including cerebrovascular disorders increase the risks for developing serious forms of the novel Coronavirus infection. COVID-19 has also been documented to produce thrombotic complications in patients with more severe forms of the disease that also required ICU care. One report documented a 31% incidence of thrombotic complications in ICU patients with COVID-19 infections.
(5) Neurological disorders
The CDC reports that neurological disorders as well as conditions affecting neurological development are an important risk factor for severe forms of COVID-19. Examples include disorders of the brain, spine and spinal cord, but also nerves and muscles and developmental disorders and seizure disorders.
Obesity is an important risk factor for complications in COVID-19 and can even increase death rates. According to a study published in the New England Journal of Medicine on the Clinical Characteristics of Covid-19 in New York City, obesity represented a risk factor for COVID-19 complications such as respiratory failure leading to mechanical ventilation. Out of a total of 393 patients confirmed with COVID-19, over 35% had obesity. Obesity is one of the leading comorbidities in COVID-19 patients under 60.
(7) Chronic lung diseases
Chronic obstructive pulmonary diseases, COPD for short, and any condition that causes impaired lung function represents a risk factor for the novel Coronavirus infection as well as COVID-19 complications. Asthma had also been initially considered as a top COVID-19 comorbidity and risk factor for complications associated with the novel Coronavirus infection. However, more recent data suggests that having asthma does not increase the risks for the novel Coronavirus infection or complications related to COVID-19. Find out more about COVID-19 and asthma.
(8) Chronic kidney disease
The CDC reports chronic kidney disease as one of the top comorbidities in COVID-19 patients. Severe infection with the novel Coronavirus can cause direct and indirect damage to the kidneys known as acute kidney injury which can increase risks for further complications and even death in case of an underlying kidney disorder.
(9) Chronic liver disease
According to the CDC, chronic liver disease is on par with chronic kidney disease in terms of the most common comorbidities in COVID-19. In severe forms of the novel Coronavirus infection, organ damage has been documented to occur. A patient’s condition can further deteriorate if the infection affects an organ that is already affected by an underlying condition, potentially resulting in increased risk of death.
A suppressed immune system can be the result of disease (HIV, AIDS), various therapies (cancer treatment or surgery such as organ or bone marrow transplantation) or corticosteroid treatment for the management of conditions requiring some degree of immunosupression (severe allergies and various other immune system disorders). A suppressed immune system is more easily affected by infection, including the novel Coronavirus infection, as well as more likely to suffer complications from infection which is why immunosuppression ranks high on the list of COVID-19 comorbidities.