This page includes explanations of key terms used in the HHS OMH Population Profiles. These definitions are meant to make the information in the HHS OMH Population Profiles accessible to most readers and are not necessarily intended for scientific or academic publications.
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Comorbidities are two or more distinct physical or mental medical conditions or diseases present in a person at the same time. For example, a person can have a mental illness like depression and a chronic disease like diabetes. Some comorbidities can co-exist without much impact on your overall health, but some comorbidities can affect each other and make managing one or both conditions more difficult.
Related terms: multiple conditions, co-occurring conditions, overlapping health issues
Health care use describes the use of medical services to maintain health, prevent illness, treat conditions, or get health information. Examples of health care use include doctor visits, hospitalizations, emergency department visits, tests, imaging, and prescription drug use. Health care use is informed by individual health needs, service availability, and insurance coverage.
5-year survival rates describe the percentage of people with a specific disease, often cancer, who are still alive five years after their diagnosis. It helps patients and doctors understand the long-term outlook, or prognosis, for a disease. Conversely, 5-year mortality rates describe the percentage of people who have died within five years of receiving their diagnosis. It is important to note that these rates are estimates and that many factors, such as age, disease type and stage, and overall health affect individual health and survival outcomes.
Mortality is another term for death. A mortality rate shows the number of deaths caused by a disease during a period of time. It is typically written as the number of deaths per 1,000 or 100,000 people per year. Mortality rates are key indicators of a population’s overall health.
Occurrence is a general term used to describe how often a disease or health event occurs in a population. It can include both incidence (new cases of a disease) and prevalence (total existing cases of a disease).
Risk factors for complications are behaviors, conditions, or other factors that increase the likelihood of experiencing severe illness, hospitalization, or dying from a disease. For example, if a pregnant woman smokes during her pregnancy, she increases the risk that her child may be born with preventable health conditions, such as low birth weight or birth defects.
Date Last Reviewed: February 2026