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Adapting a clinical comorbidity index for use with ICD-9-CM administrative databases
R A Deyo1, D C Cherkin, M A Ciol
1Department of Medicine, University of Washington, Seattle 98195.
Insights
This study adapted a clinical comorbidity index for use with administrative healthcare databases. The adapted index effectively predicted health outcomes and resource use in patients undergoing lumbar spine surgery.
Area of Science:
- Health Services Research
- Medical Informatics
- Epidemiology
Background:
- Administrative databases are valuable for healthcare outcomes research.
- Accurate assessment of disease severity and comorbidities is crucial for valid inferences from administrative data.
- Existing clinical comorbidity indices often require detailed medical record review, limiting their use with administrative codes.
Purpose of the Study:
- To adapt a clinical comorbidity index for use with International Classification of Diseases (ICD-9-CM) diagnosis and procedure codes.
- To evaluate the adapted index's association with health outcomes and resource utilization in a Medicare population undergoing lumbar spine surgery.
Main Methods:
- Adapted a clinical comorbidity index for ICD-9-CM codes.
- Examined the association of the adapted index with outcomes (complications, mortality, discharge disposition, length of stay, charges) in Medicare beneficiaries (n=27,111) who had lumbar spine surgery in 1985.
- Assessed index performance using data from a single admission versus multiple hospitalizations over a year, controlling for patient age.
Main Results:
- The adapted comorbidity index was significantly associated with adverse health outcomes and increased resource use, including postoperative complications, mortality, blood transfusion, discharge to a nursing home, longer hospital stays, and higher hospital charges.
- These associations were consistent regardless of whether the index utilized data from a single hospital admission or aggregated data from multiple hospitalizations within a year.
- The predictive validity of the index persisted after adjusting for patient age.
Conclusions:
- The adapted comorbidity index, utilizing ICD-9-CM codes, is a valid tool for assessing disease severity and comorbidity burden in administrative healthcare databases.
- This index can enhance the accuracy of research on disease outcomes and resource utilization, particularly for studies involving large patient populations.
- The index demonstrates utility for both single-admission analyses and longitudinal studies incorporating data across multiple hospitalizations.
Abstract:
Administrative databases are increasingly used for studying outcomes of medical care. Valid inferences from such data require the ability to account for disease severity and comorbid conditions. We adapted a clinical comorbidity index, designed for use with medical records, for research relying on International Classification of Diseases (ICD-9-CM) diagnosis and procedure codes. The association of this adapted index with health outcomes and resource use was then examined with a sample of Medicare beneficiaries who underwent lumbar spine surgery in 1985 (n = 27,111). The index was associated in the expected direction with postoperative complications, mortality, blood transfusion, discharge to nursing home, length of hospital stay, and hospital charges. These associations were observed whether the index incorporated data from multiple hospitalizations over a year's time, or just from the index surgical admission. They also persisted after controlling for patient age. We conclude that the adapted comorbidity index will be useful in studies of disease outcome and resource use employing administrative databases.