The following slides provide an overview of Quan et al.'s work and the importance that it plays in the transition from ICD-9 to ICD-10.

The Charlson comorbidity index contains 19 categories of comorbidity, based on ICD-9-CM diagnoses and procedure codes, and their associated weights, that provide an overall comorbidity score to reflect the cumulative increased likelihood of one-year mortality.

The Elixhauser comorbidity index defines 30 comorbid (i.e., co-existing) conditions using ICD-9-CM codes.

Please see Manitoba Centre for Health Policy's glossary and concept dictionary for more information on and research using the comorbidity indices.