Background: The validity of International Classification of Diseases-9 codes for liver disease has not been determined.
Aim: To examine the accuracy of International Classification of Diseases-9 codes for cirrhosis with hepatitis C virus or alcoholic liver disease and HIV or hepatitis B virus coinfection with hepatitis C virus in Veterans Affairs data.
Methods: We conducted a retrospective study comparing the Veterans Affairs administrative data with abstracted data from the Michael E. DeBakey VA Medical Center's medical records. We calculated the positive predictive value, negative predictive value, per cent agreement and kappa.
Results: For cirrhosis codes, the positive predictive value (probability that cirrhosis is present among those with a code) and negative predictive value (probability that cirrhosis is absent among those without a code) were 90% and 87% with 88% agreement and kappa = 0.70. For hepatitis C virus codes, the positive predictive value and negative predictive value were 93% and 92%, yielding 92% agreement and kappa = 0.78. For alcoholic liver disease codes, the positive predictive value and negative predictive value were 71% and 98%, with 89% agreement and kappa = 0.74. All parameters for HIV coinfection with hepatitis C virus were >89%; however, the codes for hepatitis B virus coinfection had a positive predictive value of 43-67%.
Conclusion: These diagnostic codes (except hepatitis B virus) in Veterans Affairs administrative data are highly predictive of the presence of these conditions in medical records and can be reliably used for research.