ABSTRACT
Preventive medicine has traditionally been the field within which prevention has been developed, drawing on knowledge of the natural history of diseases and risk factor epidemiology. Prevention can have a number of unintended consequences, including the creation of unforeseen new problems. Primary prevention aims to reduce the incidence of disease by decreasing the risk of exposure. Secondary prevention seeks to limit disease progression by early detection and intervention. Population-based targeted screening programmes are an example of secondary prevention and have been particularly directed at a number of cancers. Public health problems, by definition, occur at a population level. Two approaches to prevention are frequently debated: a population-level strategy, which would include apparently healthy people, and a strategy that targets those at high risk. Harm reduction policies and strategies are a particular form of prevention developed to minimize the harms associated with a behaviour, rather than seeking to change the behaviour itself.
