Developing Country-Specific Charlson Comorbidity Index Mappings for Use with German Administrative Data:...

Area of Science:

• Medical Informatics
• Health Services Research
• Epidemiology

Background:

• The Charlson Comorbidity Index (CCI) is a standard measure for comorbidity burden in research.
• Existing ICD-based mappings for CCI, like Quan et al. (2005), are outdated for German coding standards.
• Accurate ICD mappings are crucial for applying CCI to real-world administrative data.

Purpose of the Study:

• To develop and validate year-specific ICD-10-GM mappings for the CCI (2004-2026) in Germany.
• To create an open-source implementation for calculating CCI using these new mappings.
• To compare the performance of the new mappings against the widely used Quan et al. mapping.

Main Methods:

• Curated year-specific ICD-10-GM to CCI mappings through independent dual review.
• Applied new and Quan's mappings to 515,827 inpatient cases from a German tertiary center (2010-2024).
• Assessed agreement using Intraclass Correlation Coefficient (ICC) and discordance significance with McNemar's test.

Main Results:

• High overall agreement (96.87%) between new and Quan's mappings.
• Significant discrepancies noted in 9 of 17 CCI categories, particularly "peripheral vascular disease" (52% of discordant cases).
• Differences were more pronounced (6.86%) when analyzing malignant disease cohorts, driven by "peripheral vascular disease" mapping.

Conclusions:

• Developed transparent, year-specific ICD-10-GM mappings (2004-2026) for CCI calculation.
• Provided an open-source tool for reproducible, year-appropriate comorbidity adjustment.
• New mappings reflect current German coding practices, improving the accuracy of administrative data analysis.