Adaptation of the charlson comorbidity index for register-based research in sweden

Jonas F. Ludvigsson, Peter Appelros, Johan Askling, Liisa Byberg, Juan Jesus Carrero, Anna Mia Ekström, Magnus Ekström, Karin Ekström Smedby, Hannes Hagström, Stefan James, Bengt Järvholm, Karl Michaelsson, Nancy L. Pedersen, Helene Sundelin, Kristina Sundquist, Johan Sundström

Research output: Contribution to journalArticlepeer-review


Purpose: Comorbidity indices are often used to measure comorbidities in register-based research. We aimed to adapt the Charlson comorbidity index (CCI) to a Swedish setting. Methods: Four versions of the CCI were compared and evaluated by disease-specific experts. Results: We created a cohesive coding system for CCI to 1) harmonize the content between different international classification of disease codes (ICD-7,8,9,10), 2) delete incorrect codes, 3) enhance the distinction between mild, moderate or severe disease (and between diabetes with and without end-organ damage), 4) minimize duplication of codes, and 5) briefly explain the meaning of individual codes in writing. Conclusion: This work may provide an integrated and efficient coding algorithm for CCI to be used in medical register-based research in Sweden.

Original languageEnglish
Pages (from-to)21-41
Number of pages21
JournalClinical Epidemiology
Publication statusPublished - 2021

Subject classification (UKÄ)

  • Public Health, Global Health, Social Medicine and Epidemiology

Free keywords

  • Charlson comorbidity score
  • Comorbidity
  • Disease
  • Epidemiology
  • Public health
  • Sweden


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