A Canadian version of Charlson’s Comorbidity Index implemented as a SAS macro for application on Danish national register data.
The macro traverses main diagnosis and bidiagnoses recorded at time of hospitalization, defines 17 indicators and calculates an unweighted comorbidity index.
A patient’s CCI is calculated across records using indicators (and weights) from all previous hospitalizations. CCI is a growing index.
Here is an additional and more traditional calculation of Charlson’s Comorbidity Index including 19 indicators and weights from 1 to 6. Charlson’s Comorbidity Index is defined as the sum of all indicators. The calculation assumes access to all diagnoses on a single record, which often includes both a main diagnosis, several bi- and auxillary diagnoses.
Reference: Cross-National Comparative Performance of Three Versions of the ICD-10 Charlson Index Sundararajan et al, Medical Care, V45, N12, December 2007 (1210-1215)