Information for researchers
Information on the 45 and Up Study for inclusion in grant applications
Background
The 45 and Up Study is a large, general population cohort study designed to investigate healthy ageing. It aims to recruit 250,000 men and women aged 45 and over from the NSW general population. It will link data collected prospectively and longitudinally from participants with population databases on health and health service use. It is derived from, but not designed to be representative of, the general population (see below) and spans the adult lifespan from 45 onwards, with no upper age limit, unlike other large scale cohorts world-wide. The large number of participants will allow evaluation of differential effects of risk factors, interventions and health services use by age and other population attributes.
Funding for the infrastructure of the Study, including recruitment of participants, data entry and staffing of the Coordinating Centre, is being provided by The Cancer Council NSW; the National Heart Foundation (NSW Division); beyondblue: the national depression initiative; NSW Health; the NSW Department of Ageing, Disability and Home Care; the MBF Foundation; Macquarie Group Foundation; Freehills; the Baxter Charitable Foundation and Alma Hazel Eddy Trust (both managed by Perpetual Ltd).
Study methods
The 45 and Up Study is a prospective study planning to recruit around 250,000 men and women from the NSW general population. Potential participants are randomly sampled from the Medicare Australia database and mailed a Study questionnaire and information leaflet. There is oversampling of individuals from rural areas and of those aged 80 and over. Participants join the Study by completing the questionnaire and providing signed consent for follow-up and linkage to a range of health databases. Recruitment commenced in February 2006, with accrual of over 36,000 participants in 2006 and the remainder over the period 2007-10. Linkage to health datasets is estimated to commence in 2008 and to be updated annually.
Information on the health of Study participants is collected on the baseline questionnaire and will be enhanced through subsequent data linkage. Questionnaire information includes: demographic data, including age, postcode, education, ethnicity, type of housing; lifestyle and habits, including physical activity, smoking and alcohol consumption; current medications, history of disease and surgical procedures; functional capacity (MOS-PF) and psychological distress (Kessler-10); social support (Duke sub-scale), employment status, paid and unpaid work and income. Information to be ascertained through data linkage includes: health services use (including Medicare, Pharmaceutical Benefits Scheme, hospitalisations [with details of patterns of care] and aged care); deaths, with underlying cause; and certain incident morbidities, e.g., myocardial infarction, selected fractures, cancer and diabetes (as indicated by hospitalisation, death records, cancer registrations, specified Medicare items and medication use).
Representativeness and generalisability:
Because of the nature of cohort studies, including the “healthy cohort effect”, the 45 and Up Study will not necessarily be representative of the general NSW population 45 and over, nor is it designed to be. Hence, the research projects outlined here relate to internal comparisons within the cohort, which, provided sufficient heterogeneity of exposure is present, are valid and underlie the many contributions that cohort studies have made to the understanding of health world-wide, despite being derived from specific population sub-groups (e.g. British Doctors’ Study, US Cancer Prevention Studies, European Prospective Investigation into Cancer and Nutrition). Where population estimates of exposure or disease prevalence are required for this project, to assess the impact of findings on the wider population, more representative survey data will be used where appropriate (e.g., from the NSW Health Survey). Nevertheless, the 45 and Up Study is likely to be among the most representative large-scale cohort studies conducted world-wide.
Validation:
Questionnaire and other measurement data from large-scale cohort studies are necessarily brief, to allow a large number of participants to be included feasibly. The 45 and Up Study will use more detailed biophysical, serological and questionnaire data from other more detailed studies to validate the brief measures used, particularly those for height, weight, physical activity and psychological distress, and to quantify any likely measurement error, so that it can be investigated and accounted for.
Ethical considerations:
The study has received ethical approval to proceed from the University of NSW Human Research Ethics Committee and in-principle approval for future data linkage from NSW Health, the Department of Health and Ageing, Medicare Australia, the Department of Veterans’ Affairs, The Australian Institute of Health and Welfare, the Sydney South West Area Health Service and the NSW Cancer Institute. Individual projects using linked data will require separate approval from the relevant ethics committee and data custodian.
First mailout:
The first mailout for the Study occurred in February 2006, where around 36,000 individuals joined the Study. Preliminary results from this indicate that the study methods are feasible and acceptable, that the questionnaire is completed with minimal missing values and that sufficient heterogeneity of exposure is present in the cohort. The response rate to the Study is around 17.6%, in keeping with other cohort studies requiring extensive consent for data linkage.
Sampling frame
The sampling frame for the 45 and Up Study reflects information about potential Study candidates. Summaries of characteristics of actual participants are contained in the Study Data Book.
Participants to be mailed are randomly selected from Medicare Australia records.