Accepted for/Published in: JMIR Medical Informatics
Date Submitted: Feb 22, 2026
Date Accepted: Jul 12, 2026
Date Submitted to PubMed: Aug 13, 2026
Developing Country-Specific Charlson Comorbidity Index Mappings for Use with German Administrative Data: Methodological Comparative Study
ABSTRACT
Background:
The Charlson Comorbidity Index (CCI) is widely used to quantify comorbidity burden in observational research. Applying it to real-world data requires accurate ICD-based mappings. The commonly used mapping by Quan et al. (2005) does not reflect current German coding standards.
Objective:
To develop year-specific mappings (2004 to 2026) based on the German Modification of ICD-10 for the CCI with an open-source implementation and compare them with the mapping by Quan et al.
Methods:
For each year, mappings were curated via independent dual review with consensus. In 515,827 inpatient cases from a German tertiary center (2010-2024), year-appropriate mappings and the Quan’s mapping were applied and the scores compared. Agreement was assessed using the Intraclass Correlation Coefficient (two-way mixed-effects model for absolute agreement based on single measurement), and the significance of the discordances was measured using McNemar’s test.
Results:
Agreement was very high; 3.10% of cases differed. A single code (Z95.81) was present in 52% of the discordant cases and was intentionally excluded as not diagnostic for peripheral vascular disease.
Conclusions:
We provide transparent, year-specific ICD-10-GM (2004-2026) mappings and an open-source tool for CCI calculation. The mappings align with current German coding practice and enable reproducible, year-appropriate comorbidity adjustment using administrative data.
Citation
Request queued. Please wait while the file is being generated. It may take some time.
Copyright
© The authors. All rights reserved. This is a privileged document currently under peer-review/community review (or an accepted/rejected manuscript). Authors have provided JMIR Publications with an exclusive license to publish this preprint on it's website for review and ahead-of-print citation purposes only. While the final peer-reviewed paper may be licensed under a cc-by license on publication, at this stage authors and publisher expressively prohibit redistribution of this draft paper other than for review purposes.