Supported Comorbidity Mappings and Scores

Alessandro Gasparini


The {comorbidity} R package can be used to identify comorbidity conditions and calculate comorbidity scores based on ICD codes data. Supported mapping and weighting algorithms are described below, including relevant references.

Examples showing how to apply each algorithm are included in a separate vignette.

Supported Mapping Algorithms

The {comorbidity} package can apply comorbidity mappings corresponding to the Charlson and the Elixhauser comorbidity scores. Both ICD-9 and ICD-10 coding systems are supported, with algorithms described in the paper by Quan et al. (2005). The resulting mapping algorithms are denoted with charlson_icd9_quan and charlson_icd10_quan for the Charlson score (based on ICD-9 and ICD-10 systems, respectively), elixhauser_icd9_quan and elixhauser_icd10_quan for the Elixhauser score.

Furthermore, the Swedish (Ludvigsson et al., 2021) and Australian (Sundararajan et al., 2004) modifications of the Charlson score are implemented as well, and identified by charlson_icd10_se and charlson_icd10_am respectively.

Supported Weighting Algorithms

Different weighting algorithms have been proposed to combine the different conditions into a single measure, for both the Charlson and the Elixhauser index.

Currently, the following weighting algorithms are supported for the Charlson score:

Then, for the Elixhauser score: