Professor Tony Jorm
Professor Andrew Mackinnon
Orygen Youth Health Research Centre
Project completion year
The objectives of this project were to develop a National Depression Index and a National Anxiety Index to measure the depression and anxiety status of the Australian population, to compare data from recent surveys with that from previous surveys, and to compare relative risk of depression and anxiety between different population groups.
The indices were developed using cross-sectional data from four surveys of the Australian population – the 1997 and 2007 National Surveys of Mental Health and Wellbeing (NSMHWB) and the 2001 and 2004/5 National Health Surveys (NHS).
Six items from the K10 that most closely related to the ICD-10 diagnosis of depression and four that most closely related to a diagnosis of an anxiety disorder were used to create separate scales. The indices were developed by estimating the predicted probabilities of depression and anxiety on these separate K10 scales in the 2007 NSMHWB and then applying these predicted probabilities to the same scales in the other surveys. The 1997 NSMHWB and 2001 NHS were used as benchmarks for the respective surveys, with values greater than or less than 100 on the indices, indicating a higher or lower probability of depression and anxiety for the Australian population in the subsequent survey year.
The overall mean risks of depression and anxiety were examined, along with differences in mean risk by age, household income, employment status and geographic location (major cities, inner regional, other areas) for males and females.
There was an overall increase in the mean risk of anxiety between the 1997 and 2007 NSMHWB but no significant difference in the mean risk of depression. Significant increases in the mean risk of anxiety were observed for women aged 45-64, for employed men and women, and for women living in the inner city and other areas.
The increase in the mean risk of anxiety between 1997 and 2007 may support the need for public education to focus on anxiety disorders, particularly for older women and for employed men and women.