It has been customary to categorise prevention at different levels, in terms of primary, secondary and tertiary prevention. Thus the goal of primary prevention is reducing the incidence of disease by preventing its occurrence, secondary prevention aims to prevent progression of disease though early detection, usually by screening at an asymptomatic stage and early intervention, 69 and the goal of tertiary prevention includes minimisation of the impact of established disease, and prevention of complications and further disability through effective treatment and rehabilitation. While the terminology used can vary in different fields (for example a slightly different set of categories is often used in relation to mental health 70 ), the basic concepts and objectives of prevention are essentially the same.