The HCV National Register: towards informing the natural history of hepatitis C infection in the UK.

The aim of this paper is to describe the development of a national hepatitis C register and the completeness of the data it contains. This is a descriptive report of the structure and function of the register, including case definitions, registration and follow-up procedures, and methods used to maximize data quality and to obtain comparative data sources. The register contains data on HCV-infected individuals who acquired their infections on a known date and by a known route; to date all are transfusion recipients identified during the UK lookback exercise, who tested positive or indeterminate for anti-HCV after receiving 'infected' blood issued before the introduction of routine testing of the blood supply for anti-HCV. By 31 December 1999, 871 (87%) of 996 eligible transfusion recipients had been registered, and 984 (99%) flagged in the NHS Central Registers. Registered patients had been infected for an average of 11.1 years (SEM 0.1); around half were being cared for by clinicians with a specialist interest in liver disease. Except for the information on tobacco use, current alcohol use, and hepatitis B status, data were more than 80% complete, and for most variables, more than 90% complete. The consistency of data abstraction was found to be 98% (SEM 0.5). In conclusion, the Register contains high quality anonymised data on one of the largest cohorts of individuals with HCV infections acquired on a known date and by a known route. It could serve as a model for other chronic disease registers; developers may find the structure, design, and methodological issues addressed useful.