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A comparison of the Charlson comorbidity index derived from medical record data and administrative billing data
S M Kieszak1, W D Flanders, A S Kosinski
1Kerr L. White Institute for Health Services Research, Decatur, Georgia 30030, USA.
Insights
The Charlson Comorbidity Index from medical records (Chart Index) better predicts outcomes like mortality and complications after carotid endarterectomy than the index from billing data (ICD-9 Index). This highlights the value of detailed chart review for risk adjustment.
Area of Science:
- Medical Informatics
- Health Services Research
- Surgical Outcomes
Background:
- Administrative data are increasingly used for risk adjustment due to economic and time constraints.
- Comparing risk adjusters derived from administrative (billing) versus clinical (chart review) data is crucial for accurate patient risk assessment.
- Medicare beneficiaries undergoing carotid endarterectomy represent a key population for evaluating surgical risk adjustment tools.
Purpose of the Study:
- To compare the predictive accuracy of the Charlson Comorbidity Index derived from medical records (Chart Index) versus billing data (ICD-9 Index).
- To evaluate the performance of each index in predicting inpatient mortality, 30-day mortality, length of stay, and complications.
- To assess the utility of these risk adjusters in the context of Medicare beneficiaries hospitalized for carotid endarterectomy.
Main Methods:
- Retrospective analysis of Medicare beneficiaries hospitalized for carotid endarterectomy.
- Calculation of Charlson Comorbidity Index using both medical record data (Chart Index) and ICD-9 billing codes (ICD-9 Index).
- Logistic regression analysis to compare the predictive power of each index for key patient outcomes, controlling for demographic and clinical factors.
Main Results:
- The Chart Index significantly predicted inpatient mortality, length of stay, and complications (P < 0.05).
- The Chart Index approached significance for predicting 30-day mortality (P = 0.056).
- The ICD-9 Index showed a trend towards significance for all outcomes but did not reach statistical significance (P > 0.05 for all).
Conclusions:
- The Charlson Comorbidity Index derived from detailed medical record review (Chart Index) is a superior predictor of outcomes compared to the index derived from billing data (ICD-9 Index) in this patient cohort.
- Chart review-based risk adjustment offers greater accuracy for predicting surgical outcomes like mortality and complications.
- Findings support the use of comprehensive chart review for robust risk adjustment in administrative datasets, particularly for procedures like carotid endarterectomy.
Abstract:
The objective of this article is to compare the Charlson comorbidity index derived from medical record data (Chart Index) with the same index derived from billing data (ICD-9 Index) to determine how well each predicted inpatient and 30-day mortality, length of stay, and complications among Medicare beneficiaries hospitalized for carotid endarterectomy. Economic and time constraints have increased the need for risk adjusters derived from administrative data, yet few studies have compared these measures with those derived from chart review. Using logistic regression, the Chart Index was found to be a significant predictor of inpatient mortality, 30-day mortality, length of stay, and complications, after controlling for age, gender, and neurologic and medical risk factors (P values = 0.004, 0.056, 0.0001, and 0.042, respectively). The ICD-9 Index approached significance as a predictor of the outcomes (P values = 0.092, 0.100, 0.093, and 0.080, respectively). The Chart Index was shown to be superior to the ICD-9 Index within this patient sample.