Identifying Patients With Primary Biliary Cholangitis and Cirrhosis Using Administrative Data in a National Cohort.

Background: The accuracy of administrative codes to capture patients with both primary biliary cholangitis (PBC) and cirrhosis could be challenging because of the potential for incorrect coding due to the old nomenclature "Primary Biliary Cirrhosis." Therefore, the aim of this study was to examine the positive predictive value (PPV) of International Classification of Diseases (ICD) codes for PBC and cirrhosis.

Methods: This was a retrospective cohort study using data from the VA Corporate Data Warehouse. Eligibility criteria included adult patients diagnosed to have PBC and cirrhosis based on one inpatient or two outpatient ICD 9 or 10 codes, and were validated against chart review of each participant.

Results: We identified 1408 patients who were found to have ICD codes for both cirrhosis and PBC. The ICD 9/10 codes for PBC and cirrhosis had a PPV of 0.75 (95% CI 0.73-0.75) for cirrhosis, 0.75 for PBC (95% CI 0.73-0.78), and 0.52 (0.50-0.55) for PBC and cirrhosis. When portal hypertension was combined with ICD 9/10 codes, the PPV of cirrhosis improved to 0.92 (0.90-0.94), and that of PBC cirrhosis improved to 0.64 (0.60-0.67). By combining ICD 9/10 codes for portal hypertension and receipt of ursodeoxycholic acid (UDCA), the PPV for cirrhosis improved to 0.91 (0.88-0.94), PBC increased to 0.78 (0.74-0.82), and that for PBC cirrhosis to 0.69 (0.65-0.74).

Conclusions: In a large national cohort, the use of ICD 9/10 codes had modest reliability for identifying participants with PBC and cirrhosis. The PPV for cirrhosis can be improved by incorporating ICD 9/10 codes for portal hypertension with receipt of UDCA.