The Charlson Comorbidity Index (CCI) is one of the most widely used prognostic scoring systems in clinical medicine. Developed in 1987 by Dr. Mary Charlson and colleagues, the index was originally designed to predict 1-year mortality among hospitalized patients by quantifying the impact of comorbid conditions. Over time, it has been extensively validated across multiple populations and diseases, and it remains a cornerstone tool for risk adjustment in both clinical practice and research.

The CCI assigns weighted scores to 17 comorbidities, including cardiovascular disease, diabetes, cancer, liver disease, renal disease, and AIDS/HIV, among others. The weights (ranging from 1 to 6) reflect the relative risk of mortality associated with each condition. For example, a prior myocardial infarction carries 1 point, while metastatic solid tumor or AIDS carries 6 points. Additionally, age can be incorporated into the score, with increasing points added for each decade beyond 40 years, further refining the predictive accuracy.

In practice, the CCI helps clinicians assess prognosis, stratify patients by risk, and guide decision-making in treatment planning. For example, patients with a higher CCI may have a poorer tolerance for invasive procedures, chemotherapy, or surgery, influencing the choice of therapy. In research, the CCI is commonly used to adjust for comorbidity burden in clinical trials and observational studies, allowing for more accurate comparisons between patient populations.