Morbidity vs. Mortality: What's the Difference?
One refers to illness or disease, the other means death
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Medically reviewed by Isaac O. Opole, MD, PhDFact checked by Heather Mercer
Morbidity and mortality are similar terms that mean different things. Morbidity refers to an illness or disease. Mortality refers to death. Both are used by scientists to determine health statistics like disease incidence and all-cause mortality rates.
Morbidity and mortality are closely linked. Certain changes can influence the course of a disease and, in turn, the risk the illness can lead or contribute to death.
This article explains the difference between morbidity and mortality. It also takes a look at ways to prevent morbidities and protect your long-term health.
What Is Morbidity?
Morbidity is the state of having an illness or medical condition, either mental or physical. Such issues can progress over time and gradually affect a person's health and quality of life.
However, the term has absolutely no relationship to your likelihood of death or even how "well" or "unwell" you are. It is only when a disease or condition progresses that the impact on your health may be felt and the risk of death may increase.
People who have certain morbidities may not live as long as those who do not. It's also possible that morbidity may have no impact on a person's life expectancy or risk of death, especially if their condition is well-managed.
Examples of Morbidities
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Examples of morbidities include:
Hypertension (high blood pressure)
Osteoporosis
Related:How to Estimate Your Life Expectancy
What Is Comorbidity?
Comorbidity means that a person has more than one illness at the same time. Comorbid conditions may occur because of:
The interrelationship of organ systems (such as between the heart, lungs, and kidneys)
The route of infection is the same
Lifestyle factors (like diet or smoking) that affect multiple organ systems
Examples of common comorbidities include:
Depression and alcoholism
Diabetes and obesity
High cholesterol and heart disease
HIV and hepatitis C
Hypertension and chronic kidney disease
PCOS and osteoporosis
Comorbid diseases often make each condition worse. On the flip side, managing one comorbid condition can often have a positive effect on the other.
What Is Mortality?
Mortality is another term for death. When used in research, it usually means the number of deaths caused by an event or illness over a specific period of time.
Insurers and public health experts use these statistics to assess the impact of a disease on healthcare costs or to determine where healthcare costs are best spent.
Mortality rates describe the incidence of deaths among a specific population over a specific time. In national studies, it is typically described as the number of cases per 100,000. (In smaller studies, the mortality rate may be described as deaths per 1,000 or 10,000.)
By way of example, the current mortality rate for lung cancer among males in the United States is roughly 40 per 100,000.
When an event or a disease causes more deaths than expected, it is called excess mortality. COVID-19 is one such example. The 2020 pandemic caused 50% more deaths than were expected over that period of time.
Common Causes of Mortality in the U.S.
Around 75% of deaths in the United States are caused by the following diseases or events:
Heart disease
Cancer
Chronic lower respiratory diseases (like COPD and asthma)
Stroke
Alzheimer's disease
Diabetes
Influenza and pneumonia
Kidney disease
Suicide
Preventing Morbidities
If you are a risk of certain diseases—such as if diabetes runs in your family—you can often take steps to prevent them. By changing your diet, losing weight, and exercising regularly, you may not only avoid type 2 diabetes but also reduce your risk of heart disease.
Morbidity can also drop when people are provided health education and adequate healthcare. The current disparity in access to healthcare in the United States largely accounts for why communities of color have higher rates of morbidity and mortality from manageable conditions like diabetes and HIV.
Related:Health Disparities: What They Are and Why They Matter
