References
- Charlson ME. Charlson Comorbidity Index (CCI) www.mdcalc.com
- Charlson ME, Pompei P, Sles KL, MacKenzie CR. A new method of classifying prognostic comorbidity in longitudinal studies: development and validation pubmed.ncbi.nlm.nih.gov Journal of Chronic Diseases 1987; 40: 373-383.