What Is the Charlson Index?

The Charlson Index is a tool used to assess probable mortality for patients with multiple serious illnesses. Termed comorbidities, such conditions can interact with each other and may decrease the patient’s chance of survival. Doctors and researchers can determine a patient’s Charlson Index by adding scores assigned to each condition the patient has, resulting in a single number to indicate probable mortality. This information can be useful in clinical studies as well as preparations for treatment, where a doctor may want to consider the patient’s chance of survival when making recommendations.

Scores used for this medical assessment tool are based on study of mortality rates, with a specific focus on comorbidity, in order to accurately predict a patient’s chances of dying within a 10-year period with a given mix of diagnoses. Numerous conditions have been assigned scores under the Charlson Index including diabetes, myocardial infarction, metastatic cancer, and liver disease. To find a patient’s score, doctors can ask the patient to fill out a questionnaire and may review medical records as well.

One reason to use this tool is in treatment planning for a patient. If someone with severe liver disease and poorly controlled diabetes is diagnosed with a metastatic tumor, for instance, the chances of survival can be slim because of the comorbidities. In addition, the patient may not be able to tolerate the aggressive treatments that would be needed to address the cancer. Based on the Charlson Index for that patient, it might be advisable to recommend palliative care to control the conditions and limit pain, without pursuing aggressive management.

Not treating medical conditions can seem counter-intuitive but may be necessary if the treatment is likely to harm the patient or doesn’t offer enough of a net benefit. Someone who is likely to die in a year of other medical conditions, for example, does not have very much to gain from aggressive cancer care. Conversely, a patient with a low Charlson Index can be an excellent candidate for aggressive therapy to address a specific medical issue, because of the high chance of survival.

Medical researchers can use tools like the Charlson Index to quantify data and provide definitive information for other scientists. People might start a study by assigning Charlson Index scores to the participants so they can refer to this information later when assessing their results. They can also conduct a study to determine if this type of scoring is appropriate for a given set of comorbidities, to confirm that doctors are using it correctly.