Cohort profile: the 45 and up study

In common with virtually all industrialized countries and many less developed nations, Australia is facing rapid population ageing. Historical patterns of fertility and migration, along with changes in life expectancy, mean that the over 65 age group is likely to increase by around 50% in the next 15–20 years.1 The further increase in the proportion of people in the very old age groups will result in the ‘ageing of the aged’. The challenges presented by the ageing of the population are far reaching. Discussions have tended to focus on its likely health and economic consequences; however, few aspects of society will remain unaffected by the issue. There is an urgent need for reliable evidence to inform policy to support healthy ageing. The concept of healthy ageing encompasses traditional ideas relating to freedom from disease, as well as broader considerations including independence, quality of life, management of disability, participation in society and the workforce and productivity. A wide range of factors are likely to affect health in later life, including socioeconomic, environmental and cultural variables, cigarette smoking, alcohol consumption, diet, physical activity, reproductive and hormonal factors, infections, availability of healthcare and use of pharmaceutical agents, as well as individuals’ susceptibility to disease. A comprehensive investigation of the determinants of healthy ageing must incorporate assessment of disease risk, quality of life and other indices, in relation to a very wide range of possible exposures, and with consideration of how these exposures might interact with one another. Research needs to be of a sufficient scale to provide specific information on the major diseases and health problems experienced in later life. This is because reliable assessments of risk factor–disease relationships require a substantial degree of pathological homogeneity of outcome and appropriate consideration of confounding. At the same time, research needs to be able to assess the broad risks and benefits of particular exposures, to allow meaningful conclusions to be reached about suitable public health interventions. Finally, it needs to be large and long term enough to track the impact of health interventions and policies at the population level