Charlson Comorbidity Index Calculator
The Charlson Comorbidity Index calculator estimates survival in patients with multiple comorbidities. It consists of 17 items, which are related to various health conditions that are associated with mortality. The Charlson index can predict short and longterm outcomes, including function, length of hospitalization, and mortality rates. Check the article below to find out how to calculate the Charlson Comorbidity Index score.
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What is Charlson Index?
The Charlson Comorbidity Index was developed in 1987 by Charlson and colleagues as a way to classify comorbid conditions which may influence mortality risk. This tool was originally supposed to be used in longitudinal studies. The initial Charlson Index was created using 19 categories but has been modified since to contain 17 or 12 items. Nowadays, the CCI is one of the most widely used scoring systems for comorbidities used in research and clinical settings.
How to calculate Charlson Comorbidity Index
The Charlson Comorbidity Index calculator consists of 17 items. Each item can be scored from 0 to 6 points and each has a different weight (which is based on the strength of the item's association with 1year mortality, as presented in the paper by Charles et al.). This is why some variables can score only 1 point at most (e.g. history of myocardial infraction), while others can score as many as 6 points (e.g. metastatic tumor).
The table below shows how many points each item scores.
Additional information:
 If the comorbidity is not present, patients score 0 points for that comorbidity.
 Patients who are 50 years old or more should get additional points as follows:
 5059 years old  additional 1 point;
 6069 years old  additional 2 points;
 7079 years old  additional 3 points; and
 80 years old or more  additional 4 points.
Charlson Comorbidity Index score
The maximum Charlson Comorbidity Index score (adjusted for age) is 37 points. After scoring each comorbidity, the patient's 10year survival rate can be calculated. It is estimated using a theoretical lowrisk population, whose 10year survival is 98.3%. The formula is:
10y survival = 0.983^(e^{CCI*0.9})
where:

e
 Euler's number, the mathematical constant that is equal to approx. 2.71828; and 
CCI
 the Charlson Comorbidity Index score adjusted for age.
Charlson Comorbidity Index calculator  a practical example
Let's use a practical example to show you how to calculate Charlson Comorbidity Index.
 Characteristics of our exemplary patient:
 Age: 57 years old;
 Comorbidities: diabetes controlled with medication, myocardial infraction (heart attack) 5 years ago; and
 Patient does not report any other health conditions.
 Charlson Comorbidity Index score of our patient equals 3:
 +1 point for the age between 50 and 59;
 +1 point for controlled diabetes; and
 +1 point for the history of myocardial infraction.

Finally, we can calculate 10year survival for this patient as follows:
10y survival = 0.983^(e^{CCI*0.9})
10y survival = 0.983^(2.71828^{3*0.9})
10y survival = 0.983^(2.71828^{2.7})
10y survival = 0.983^{14.88}
10y survival = 0.7748 = 77.48%