Cohort Profile: The National Institute for Health Research Health Informatics Collaborative: Hepatitis B Virus (NIHR HIC HBV) research dataset.

Purpose: The National Institute for Health Research (NIHR) Health Informatics Collaborative (HIC) was established to enable re-use of routinely collected clinical data across National Health Service (NHS) Trusts in the United Kingdom to support translational research. Viral hepatitis is one of the first five exemplar themes and hepatitis B virus (HBV) is the current focus of the theme. The NIHR HIC HBV dataset, derived from the central data repository of NIHR HIC viral hepatitis theme, aims to describe and characterise HBV infection in secondary care in the United Kingdom, and provides a resource for translational research. Participants: The dataset comprises >5000 individuals (99% adults aged [≥]18, 1% children aged <18) with chronic HBV (CHB) infection from five NHS Trusts across England, representing clinical data collected between August 1994 and August 2021. Findings to date: Data on demographics, laboratory tests, antiviral treatment, elastography scores, imaging/biopsy reports, death information, and potential risk factors for liver disease have been collected. Data are captured by electronic patient record (EPR) systems, and records are updated prospectively as new results are added. This cohort profile describes the dataset in its current form. Among the adults, 55% are male, and the median age at index date (defined as the first recorded positive hepatitis B virus surface antigen (HBsAg) or HBV DNA in EPR systems) was 40 years (interquartile range [IQR]: 32-50). For those individuals with ethnicity reported, 30% were Asian, 24% were Black, 30% were White, and the remaining 16% were mixed or other ethnic groups. Currently, the median follow-up duration of the adult patients in this dataset was 5.0 (IQR: 2.7-7.5) years, with 9.3 (95% CI: 8.2-10.5) deaths per 1,000 person-years. We have already conducted several analyses using subsets of this dataset including an evaluation of distribution and trajectories of HBsAg and HBV viral load in CHB, reviewing the use of antiviral treatment, quantifying the burden of liver disease in the untreated population, and studying the use of laboratory biomarkers to improve stratification and surveillance. Future plans: Longitudinal data collection is continuing, with the sample growing in size, more parameters being collected, average follow-up increasing, and more NHS Trusts participating. This dataset offers important opportunities for epidemiological studies and biomedical informatics research, as well as characterising an HBV population for clinical trials through external collaborations with industry.