The value of time in longitudinal studies of ageing. Lessons from the Australian Longitudinal Study on Women's Health.

The Australian Longitudinal Study on Women's Health (ALSWH) involves three cohorts of women born in 1921-1926, 1946-1951 and 1973-1978, who have been surveyed every 3 years since 1996. We describe how the 1921-1926 cohort have changed over time. We also describe trends in health risks among the younger cohorts, providing an indication of future health threats. By Survey 5, 28.4% of the 1921-1926 cohort had died. Among those who survived and remained in the study, 61% maintained high physical function scores over time. Chronic conditions such as arthritis, diabetes, heart disease and stroke were associated with lower physical function scores and decline in scores over time. ALSWH will continue to provide information on changes in health and health service use as we follow the oldest cohort through their 90 s, and as younger cohorts accumulate increasing burden of disease and disability as they age.