ABSTRACT
Surveillance of chronic hepatitis C virus (HCV) cases faces limitations that result in delays and under-reporting. With increasing use of electronic health records (EHRs), the authors evaluated the predictive value of using International Classification of Diseases, Ninth Revision (ICD-9) codes to identify chronic HCV cases from EHR data. Longitudinal EHR data from 4 health care systems during 2006-2012 were evaluated. Using chart abstraction and review to confirm chronic HCV cases ("gold standard" definition), the authors calculated the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of 2 case definitions: (1) ≥2 ICD-9 codes separated by ≥6 months and (2) ≥1 positive HCV RNA (ribonucleic acid) test. Among 2,718,995 patients, 20,779 (0.8%) with ICD-9 codes indicating a likely diagnosis of chronic HCV infection were identified; 13,595 (65.4%) of these were randomly selected for review. Case definition 1 (≥2 ICD-9 codes separated by ≥6 months) had 70.3% sensitivity, 91.9% PPV, 99.9% specificity, and 99.9% NPV while case definition 2 (≥1 positive HCV RNA test) had 74.1% sensitivity, 97.4% PPV, 99.9% specificity, and 99.9% NPV. The predictive values of these alternate EHR-derived ICD-9 code-based case definitions suggest that these measures may be useful in capturing the burden of diagnosed chronic HCV infections. Their use can augment current chronic HCV case surveillance efforts; however, their accuracy may vary by length of observation and completeness of EHR data.
ABSTRACT
BACKGROUND: Hepatitis A and B vaccines are effective in preventing superinfection and sequelae in patients with chronic hepatitis B or C. We describe immunity and vaccination against hepatitis A and B in chronic hepatitis patients from the US Chronic Hepatitis Cohort Study. METHODS: We identified chronic hepatitis B and C patients with healthcare utilization during 2006-2008 and 12 months of enrollment. We used electronic laboratory records to determine immunity and medical and billing records for vaccination history. Immunity against hepatitis A was defined by positive hepatitis A antibody or documented vaccination. Immunity against hepatitis B was defined as hepatitis B surface antibody level ≥10 mIU/mL or core antibody positive, or by documented vaccination. RESULTS: Among 1635 chronic hepatitis B patients, 978 (59.8%) were immune or vaccinated against hepatitis A, 122 (7.5%) had negative hepatitis A antibody tests, and 535 (32.7%) had no testing or vaccination record. Among 5328 chronic hepatitis C patients, 2998 (56.3%) were immune or vaccinated against hepatitis A, 659 (12.4%) had negative hepatitis A antibody tests, and 1671 (31.4%) had no testing or vaccination record. Additionally, 3150 (59.1%) chronic hepatitis C patients were immune or vaccinated against hepatitis B, 1003 (18.8%) had a negative test result, and 1175 (22.1%) were neither tested for nor vaccinated against hepatitis B. CONCLUSIONS: Approximately 40% of chronic hepatitis B and C patients are susceptible to or have no documented immunity or vaccination against hepatitis A or hepatitis B. Clinicians should consider antibody testing and vaccination for this vulnerable population.
