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. 2010 Jan 5:11:1.
doi: 10.1186/1471-2296-11-1.

Adaptation and validation of the Charlson Index for Read/OXMIS coded databases

Nada F Khan  1 , Rafael Perera, Stephen Harper, Peter W Rose
Affiliations

Adaptation and validation of the Charlson Index for Read/OXMIS coded databases

Nada F Khan et al. BMC Fam Pract. .

Abstract

Background: The Charlson comorbidity index is widely used in ICD-9 administrative data, however, there is no translation for Read/OXMIS coded data despite increasing use of the General Practice Research Database (GPRD). Our main objective was to translate the Charlson index for use with Read/OXMIS coded data such as the GPRD and test its association with mortality. We also aimed to provide a version of the comorbidity index for other researchers using similar datasets.

Methods: Two clinicians translated the Charlson index into Read/OXMIS codes. We tested the association between comorbidity score and increased mortality in 146 441 patients from the GPRD using proportional hazards models.

Results: This Read/OXMIS translation of the Charlson index contains 3156 codes. Our validation showed a strong positive association between Charlson score and age. Cox proportional models show a positive increasing association with mortality and Charlson score. The discrimination of the logistic regression model for mortality was good (AUC = 0.853).

Conclusion: We have translated a commonly used comorbidity index into Read/OXMIS for use in UK primary care databases. The translated index showed a good discrimination in our study population. This is the first study to develop a co-morbidity index for use with the Read/OXMIS coding system and the GPRD. A copy of the co-morbidity index is provided for other researchers using similar databases.

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Figures

Figure 1
Figure 1
Translation of Charlson index to Read/OXMIS codes.
Figure 2
Figure 2
Breakdown of Charlson score in patient dataset.
Figure 3
Figure 3
5 year mortality stratified by Charlson score.
Figure 4
Figure 4
ROC curve for logistic regression model.
See this image and copyright information in PMC

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