Changes in the prevalence of psychological distress and use of antidepressants or anti-anxiety medications associated with comorbid chronic diseases in the adult Australian population, 2001-2008

Objective: To investigate changes in the prevalence of psychological distress and use of antidepressants or anti-anxiety medications associated with comorbid chronic diseases in the adult Australian population from 2001 to 2008. Methods: Participants were 48,359 adults aged >= 25 years from the 2001, 2004-05 or 2007-08 Australian National Health Surveys. Clinically significant psychological distress was determined with the 10-item Kessler Psychological Distress Scale (using scores >= 30). Contemporaneous use of antidepressants or anti-anxiety medications and the presence of chronic diseases including diabetes, cardiovascular disease, cancer, asthma and arthritis were by self-report. Results: Overall, the prevalence of psychological distress was relatively stable (3.9 vs. 3.7%) between 2001 and 2008, but increased from 5.9 to 7.0% and 4.6 to 5.0% for people with diabetes and cardiovascular disease. In contrast, the use of antidepressants or anti-anxiety medications decreased from 7.3 to 4.8% across all disease categories. On average, the odds of psychological distress and use of antidepressants or anti-anxiety medications was 1.15 to 1.59-fold and 1.10 to 1.64-fold higher, respectively, for all chronic diseases after adjustments for socio-demographic and lifestyle variables. After further adjustment for all chronic disease predictors fitted jointly, these associations decreased in strength (percentage change in the log odds ratio) by 14 to 98%. Each additional chronic disease increased the odds of both psychological distress (1.34-fold higher) and use of antidepressants or anti-anxiety medications (1.40-fold higher) in a dose response manner. Conclusions: Although the prevalence of psychological distress changed little for adult Australians between 2001 and 2008, it increased for people with diabetes and cardiovascular disease. Conversely, the reported use of antidepressants or anti-anxiety medications progressively decreased for people with, and without, chronic diseases. Overall, there was a persistently higher psychopathology burden associated with each and increasing number of comorbid chronic diseases.