What does comorbidity mean?
Comorbidity is a noun used chiefly in medicine and public health to describe the situation in which a person has two or more diseases or disorders at the same time. For example, a patient diagnosed with heart failure might also have diabetes and chronic kidney disease — a pattern clinicians call comorbidity, and which often makes each condition harder to treat. The word is especially prominent in psychiatry, where it describes overlapping diagnoses such as depression occurring alongside anxiety, and in addiction medicine, where it underlies the idea of dual diagnosis. Related terms include morbidity, meaning the state of being diseased, and multimorbidity, used when no single condition is treated as primary. Coined by the American physician Alvan Feinstein in 1970, from Latin roots meaning 'together' and 'diseased', comorbidity has become indispensable to modern research on aging, chronic illness, and healthcare costs, since patients with multiple conditions typically need more complex, coordinated care.
nounThe co-occurrence of two or more medical conditions in the same person at the same time. More broadly, it refers to any additional condition or disorder existing alongside a primary one, especially in clinical or research contexts.
- The presence of one or more additional diseases or disorders co-occurring with a primary disease in a patient.
- In psychiatry and addiction medicine: the co-occurrence of a mental health disorder with another mental health or substance use disorder (e.g., 'dual diagnosis').
"Diabetes is common in patients with hypertension, and their comorbidity complicates treatment decisions."
"Older adults often live with comorbidity, managing several chronic illnesses at once."
"Depression shows high rates of comorbidity with anxiety disorders."
Used when referring to multiple distinct co-occurring conditions or across different patients.
"Patients with multiple comorbidities require carefully coordinated treatment plans."
The word 'comorbidity' didn't exist before 1970 — a single epidemiologist, Alvan Feinstein, coined it to describe a problem doctors had always noticed but never had a name for.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of comorbidity
Comorbidity was coined in 1970 by the American physician and epidemiologist Alvan Feinstein in his work on clinical methodology. It combines the prefix 'com-' from Latin 'cum', meaning 'with' or 'together', with 'morbidity', derived from Latin 'morbidus', meaning 'diseased' or 'sick', itself from 'morbus', meaning 'disease'. The same root gives English the words morbid, morbidity, and morbidly.
Related word forms
How comorbidity is actually used
A formal, technical term used mainly in medicine, public health, psychology, and epidemiology; rare in casual conversation. In everyday speech people more often say someone 'has two conditions' or 'has diabetes as well as heart disease.' Some clinicians distinguish 'comorbidity' (a secondary condition alongside an index disease) from 'multimorbidity' (two or more conditions without privileging one as primary).
Easily confused with comorbidity
Mortality refers to death or death rates within a population, while comorbidity refers to multiple conditions occurring together in one patient.