**4.7 Charlson comorbidity index (CCI)**

First developed in 1987 as a weighted approach to assess risk of death within 1-year of hospitalization with specific comorbid conditions [50]. The index assigns value to 19 medical conditions (i.e., diabetes, heart failure, peripheral vascular disease, chronic pulmonary disease, liver disease, renal disease, hemiplegia, etc.) according to presence and severity. The sum is used to estimate the risk of death. CCI is the most common comorbidity assessment utilized and has been validated in multiple solid and hematologic malignancies [51–54].
