Adaptation of the Charlson Comorbidity Index for Register-Based Research in Sweden

• Published in: Clinical epidemiology Vol. 13; pp. 21 - 41
• Main Authors: Ludvigsson, Jonas F, Appelros, Peter, Askling, Johan, Byberg, Liisa, Carrero, Juan-Jesus, Ekström, Anna Mia, Ekström, Magnus, Smedby, Karin Ekström, Hagström, Hannes, James, Stefan, Järvholm, Bengt, Michaelsson, Karl, Pedersen, Nancy L, Sundelin, Helene, Sundquist, Kristina, Sundström, Johan
• Format: Journal Article
• Language: English
• Published: New Zealand Dove Medical Press Limited 01.01.2021; Taylor & Francis Ltd; Dove; Dove Medical Press
• Subjects: Acquired immune deficiency syndrome; Adaptation; AIDS; Algorithms; Cancer; Cardiomyopathy; Cardiovascular disease; Cerebrovascular disease; Charlson comorbidity score; Chronic obstructive pulmonary disease; Classification; Clinical medicine; Codes; Comorbidity; Dementia; Diabetes; Disease; Epidemiology; Health Sciences; Heart attacks; Heart failure; HIV; Human immunodeficiency virus; Hälsovetenskap; Kidney diseases; Leukemia; Liver diseases; Medical and Health Sciences; Medicin och hälsovetenskap; Methodology; Mortality; Public health; Rheumatic diseases; Stroke; Sweden; Ulcers; Sweden; epidemiology; Sweden; comorbidity; disease; Charlson comorbidity score; public health
• ISSN: 1179-1349; 1179-1349
• DOI: 10.2147/CLEP.S282475

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. Four versions of the CCI were compared and evaluated by disease-specific experts. 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. This work may provide an integrated and efficient coding algorithm for CCI to be used in medical register-based research in Sweden.