Antidepressant use and depressive symptomatology among older people from the Australian Longitudinal Study of Ageing

Background: Depression is one of the leading contributors to the burden of non-fatal diseases in Australia. Although there is an overall increasing trend in antidepressant use, the relationship between use of antidepressants and depressive symptomatology is not clear, particularly in the older population. Methods: Data for this study were obtained from the Australian Longitudinal Study of Ageing (ALSA), a cohort of 2087 people aged over 65 years at baseline. Four waves of home interviews were conducted between 1992 and 2004 to collect information on sociodemographic and health status. Depressive symptoms were measured by the Center for Epidemiologic Studies - Depression Scale. Use of antidepressants was based on self-report, with the interviewer able to check packaging details if available. Longitudinal analysis was performed using logistic generalized estimating equations to detect if there was any trend in the use of antidepressants, adjusting for potential confounding factors. Results: The prevalence of depressive symptoms was 15.2% in 1992 and 15.8% in 2004 (p > 0.05). The prevalence of antidepressant users increased from 6.5% to 10.9% (p < 0.01) over this period. Among people with depressive symptoms, less than 20% were taking antidepressants at any wave. Among people without depressive symptoms, the prevalence of antidepressant use was 5.2% in 1992 and 12.0% in 2004 (p < 0.01). Being female (OR = 1.67, 95%CI: 1.25-2.24), having poor self-perceived health status (OR = 1.17, 95%CI: 1.04-1.32), having physical impairment (OR = 1.48, 95%CI: 1.14-1.91) and having depressive symptoms (OR = 1.62, 95%CI: 1.24-2.13) significantly increased the use of antidepressants, while living in community (OR = 0.51, 95%CI: 0.37-0.71) reduced the risk of antidepressant use. Conclusions: Use of antidepressants increased, while depressive symptoms remained stable, in the ALSA over a 12-year period. Use of antidepressants was low for people with depressive symptoms.