Comorbidities

Comorbidity is the presence of one or more additional diseases or conditions that occur with a primary disease in an individual. It is a common term in clinical practice and research to describe how other health problems affect the main condition. Some authors distinguish comorbidity from multimorbidity, with comorbidity focusing on a primary disease and multimorbidity treating all conditions equally. In practice, comorbid conditions can influence symptoms, prognosis, treatment choices, and overall care needs.

Prevalence and impact: Comorbidity is common, especially in older adults and in people with chronic diseases. Coexisting conditions can worsen prognosis, increase hospitalizations and health care costs, and reduce quality of life. They can also complicate diagnosis and management because symptoms, tests, and drug effects may overlap.

Common patterns: Cardiovascular disease often coexists with hypertension, diabetes, and obesity; cancer with fatigue or depression; chronic lung disease with anxiety or sleep disorders. Mental health conditions frequently accompany physical illness and can affect treatment adherence and outcomes.

Assessment and management: Tools such as the Charlson Comorbidity Index or Elixhauser Index quantify burden for prognosis and research. Clinically, care emphasizes integration and patient-centered planning, careful medication review to reduce polypharmacy and interactions, and coordination across specialties. Multidisciplinary teams and rehabilitation or palliative approaches may help achieve functional goals.

Research and policy: Trials often exclude patients with multiple conditions, highlighting the need for inclusive design. Policies that support integrated care and value-based payment aim to address the needs of people with comorbidity.