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We review the origins of backcalculation (or back projection) methods developed for the analysis of AIDS (acquired immunodeficiency syndrome) incidence data. These techniques have been used extensively for >15 years to deconvolute clinical case incidence, given knowledge of the incubation period distribution, to obtain estimates of past HIV (human immunodeficiency virus) infection incidence and short-term predictions of future AIDS incidence. Adaptations required for the analysis of bovine spongiform encephalopathy (BSE) incidence included: stratification of BSE incidence by age as well as birth cohort; allowance for incomplete survival between infection and the onset of clinical signs of disease; and decomposition of the age- and time-related infection incidence into a time-dependent feed risk component and an age-dependent exposure/susceptibility function. The most recent methodological developments focus on the incorporation of data from clinically unaffected cattle screened using recently developed tests for preclinical BSE infection. Backcalculation-based predictions of future BSE incidence obtained since 1996 are examined. Finally, future directions of epidemiological analysis of BSE epidemics are discussed taking into account ongoing developments in the science of BSE and possible changes in BSE-related policies.

Original publication

DOI

10.1191/0962280203sm337ra

Type

Journal article

Journal

Statistical methods in medical research

Publication Date

06/2003

Volume

12

Pages

177 - 190

Addresses

Department of Infectious Disease Epidemiology, Faculty of Medicine, Imperial College, London, UK. c.donnelly@imperial.ac.uk

Keywords

Animals, Cattle, Humans, HIV Infections, Encephalopathy, Bovine Spongiform, Incidence, Data Interpretation, Statistical, Epidemiologic Research Design, United Kingdom