Date of Award


Document Type


Degree Name

Doctor of Health Administration


College of Health Professions

First Advisor

Kit N. Simpson

Second Advisor

Trudie Millner

Third Advisor

Sarah S. Kramer

Fourth Advisor

James S Zoller


Medicare uses a risk adjustment model to prospectively determine expenses for Part C (Medicare Advantage) beneficiaries; this provides a financial incentive to report higher diagnosis code specificity in order to receive greater reimbursement. There has been little published research on diagnosis coding variation in physician practices, and the number of Medicare Advantage patients continues to rise. This study seeks to determine if ICD-9- CM code specificity for chronic kidney disease, hypertension and diabetes treated in physician office visits increased after the creation of the Hierarchical Condition Category payment methodology for Medicare patients in 2004. A retrospective review of claims data from MEDPAR’s and MarketScan® was conducted and showed increased specificity for chronic kidney disease and diabetes in both data sets over a four year period. However, the Medicare 5% sample revealed a decrease in specificity for hypertension during the same time frame in contrast to the MarketScan® sample. Further research is needed on coding accuracy and reasons for increased diagnosis code specificity in the physician office setting.


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