Conditions can be identified using the International Classification of Diseases (ICD) diagnosis codes commonly used in patient records.
The measurement was developed by Anne Elixhauser and colleagues in 1998 and initially included 30 diseases with a uniform weighting for each.
The methodology has been adapted several times since then, with the introduction of weights in 2009[2] and adjustments to the list of categories considered.
[3] The measure is most similar to the Charlson Comorbidity Index (CCI), which considers a smaller set of diseases and applies different weights.
In 2009, van Walraven et al. have derived and validated an Elixhauser comorbidity index that summarizes disease burden and can discriminate for in-hospital mortality.