Obesity is an example of a comorbidity. Comorbidities are diseases, illnesses, and conditions present in someone with another problem as well. For example, say a patient has a torn rotator cuff of the shoulder. The same patient also has a peptic ulcer, asthma, and heartburn. These extra problems are comorbidities.

Many aging adults have two or more comorbidities. They are said to have "multiple comorbidities." Some of the most common are arthritis, low back pain, high blood pressure, diabetes, heart disease, depression, and cancer.