What is the difference between the Charlson index and the age-adjusted version?

The original Charlson index only sums the comorbidity weights; the age-adjusted version (age-comorbidity Charlson index) adds 1 point per decade of life from age 50 onward to improve 10-year mortality prediction.

What Charlson score is considered high?

There is no single universal cut-off, but in general a score of 0 indicates low comorbidity, 1-2 intermediate, 3-4 high and ≥5 very high, with estimated survival declining progressively as the score rises.

Can the Charlson index predict ICU or short-term in-hospital mortality?

It is not designed for that; the CCI measures chronic comorbidity burden and long-term survival, not acute severity. For short-term mortality, dedicated scores such as APACHE II or SOFA should be used instead.

Charlson Comorbidity Index Calculator — Age-adjusted comorbidity index predicting 10-year mortality.

What it is and when to use it

The Charlson Comorbidity Index (CCI) is a prognostic tool that estimates a patient's 10-year mortality based on the burden of coexisting chronic conditions. It assigns weights of 1 to 6 points across 19 comorbidity categories (for example myocardial infarction, congestive heart failure, chronic kidney disease, diabetes with end-organ damage, liver disease, cancer and AIDS), so that conditions with greater impact on survival contribute more points. It is the most widely used comorbidity index in clinical and epidemiological research for risk adjustment; the age-combined version (age-adjusted Charlson comorbidity index) adds 1 point for each decade of age from 50 years onward.

How to interpret it

The total score is the sum of the weights of all comorbidities present (plus the age points if the age-adjusted version is used). A score of 0 indicates no significant comorbidity and the best expected survival; the higher the score, the greater the disease burden and the lower the estimated 10-year survival. It is commonly stratified into low (0), intermediate (1-2), high (3-4) and very high (≥5) comorbidity categories. Charlson's original formulation associated a 10-year survival of roughly 99% with 0 points, declining progressively with each additional point; the survival tables of the relevant validation cohort should be used rather than memorizing isolated percentages.

Limitations and when not to use it

The CCI was originally developed and validated in a cohort of inpatients on a general medicine service and subsequently in breast cancer patients, and has been widely applied using administrative codes (ICD-9/ICD-10), which may underestimate uncoded comorbidities. It is a measure of chronic disease burden, not acute severity: it does not assess functional status, frailty, cognitive status or the severity of the current acute episode, and should not be used in isolation for individual treatment decisions or as a predictor of short-term in-hospital mortality. Several versions with differing weights and updates (Deyo, Quan) exist and are not interchangeable.

Frequently asked questions

What is the difference between the Charlson index and the age-adjusted version?: The original Charlson index only sums the comorbidity weights; the age-adjusted version (age-comorbidity Charlson index) adds 1 point per decade of life from age 50 onward to improve 10-year mortality prediction.
What Charlson score is considered high?: There is no single universal cut-off, but in general a score of 0 indicates low comorbidity, 1-2 intermediate, 3-4 high and ≥5 very high, with estimated survival declining progressively as the score rises.
Can the Charlson index predict ICU or short-term in-hospital mortality?: It is not designed for that; the CCI measures chronic comorbidity burden and long-term survival, not acute severity. For short-term mortality, dedicated scores such as APACHE II or SOFA should be used instead.