The main outcome measure in this study is non-specific psychological distress, as measured by the Kessler 10 (K10) [14] . The K10 was selected because it is a well-established and validated measure that is used widely in population research in Australia, it has been used in population health surveys in NSW [15] , Victoria [16] , South Australia [17] , and Western Australia [18] , as well as in National surveys conducted by the Australian Bureau of Statistics [19] , and therefore State and National prevalence data are available as benchmarks for the current study. Scores from the K10 can be related to levels of intervention, with 'very high' psychological distress scores (> 30) equating to 'caseness' for a mental disorder, and high scores are strongly associated with current diagnosis of anxiety and depression using the Composite International Diagnostics Interview (CIDI) [20] . The K10 is also able to discriminate between DSM-IV cases and non-cases, and is felt to be an appropriate screening instrument for identifying likely cases of anxiety and depression in the population providing a strong marker for a possible mental health disorder [21] [22] [23] .