Elsevier

Journal of Affective Disorders

Volume 258, 1 November 2019, Pages 83-88
Journal of Affective Disorders

Research paper
Antidepressant use and its relationship with current symptoms in a population-based sample of older Australians

https://doi.org/10.1016/j.jad.2019.07.067Get rights and content

Highlights

  • Antidepressant use in this sample of older people was higher than national average.

  • 1/5 respondents dispensed an antidepressant did not self-report use of the medicine.

  • Self-reported depression, anxiety, pain and suicidality predicted antidepressant use.

Abstract

Background

Australia has the second highest per capita users of antidepressants globally, and their use is pronounced in older Australians. A better understanding of antidepressant use in older adults is important because the elderly are often prescribed multiple drugs, without review, for long periods.

Methods

This study analysed questionnaire data obtained from the Personality and Total Health through life project. Individual respondent data was linked to Pharmaceutical Benefits Scheme (PBS) records. Associations between self-reported medicine use and current symptoms with antidepressant dispensing were examined.

Results

1275 participants aged over 65 were included in the final analysis. One hundred and forty-six (11.5%) participants were dispensed an antidepressant within the specified timeframe. Of those, 38.4% self-reported that they use medicine for depression, 12.3% for anxiety, 17.8% for both depression and anxiety, 6.2% for sleep problems and 3.4% for pain. One fifth of those dispensed an antidepressant did not self-report use of the medicine. Being female or reporting symptoms of depression, anxiety or suicidality were significant predictors of being on an antidepressant. Increasing pain severity was also associated with increased likelihood of being on an antidepressant.

Limitations

We have presented a cross-sectional analysis, which can only provide associations between current symptoms and medicine use. We have only assessed respondents who received their scripts with PBS concession, which limits generalizability.

Conclusion

Our analysis highlights the high use of antidepressants in the elderly for various reasons. Our findings also uncovered a high amount of under-reporting of antidepressant use by respondents.

Introduction

The rising utilisation of antidepressants in the past decade has been reported by many countries around the world (Gusmão et al., 2013, OECD 2015). Australia ranks as the second highest per capita user of antidepressants among 23 Organisation for Economic Co-operation and Development countries (OECD, 2015), constituting almost 70% of all mental health-related prescriptions between 2016 and 2017 (AIHW, 2018). Use of antidepressants is pronounced in older Australians; with dispensing in those over the age of 65 almost double that of 18–65 year olds in 2013–2014, as shown by an analysis of Pharmaceutical Benefits Scheme (PBS) data conducted by the Australian Commission of Safety and Quality in Healthcare (AIHW, 2015). In contrast, the 2007 National Survey of Mental Health and Wellbeing found that Australians aged over 65 have the lowest proportion of anxiety and affective disorders compared to younger age groups (ABS, 2008), which was similarly found in the Eastern Mediterranean region using findings from the global burden of disease 2015 study (GBD, 2018). The marked use of antidepressants in the elderly in Australia has also been found in the United States (Zhong et al., 2014), Netherlands (Sonnenberg et al., 2008), Canada, Taiwan and England (Tamblyn et al., 2019). A better understanding of antidepressant use in older adults is important because older adults are often on multiple drugs, without review for long periods (Maher et al., 2014).

In Australia antidepressants are primarily indicated for moderate-to-severe major depression, and only for mild depression, anxiety and eating disorders after, or in conjunction with, psychotherapy (AMH, 2018). They can also be used for off-label indications such as chronic or neuropathic pain and urinary incontinence (AIHW, 2015). Off-label prescribing refers to prescribing outside of the indication listed in the product information for that drug – it is largely unavoidable and very common (Day, 2013). Suicidality is another important factor to consider when questioning the rationale behind high prescribing rates of antidepressants. Use of antidepressants is not indicated for prevention of suicide but suicide is strongly associated with presence of mood disorders for which antidepressants are indicated (Bertolote et al., 2003). A recent Cochrane review has concluded there is not enough evidence to draw firm conclusions regarding pharmacological interventions to reduce risk of repeat self-harm (Hawton et al., 2015). The Royal Australian and New Zealand College of Psychiatrists do not recommend use of antidepressants for management of deliberate self-harm, unless indicated for underlying depression or anxiety (Carter et al., 2016). The Australian Medicine Handbook recommends that patients with severe major depression accompanied by suicidal behaviour should be managed by a psychiatrist and when antidepressants are used treatment with the most toxic classes of antidepressants (i.e. tricyclic antidepressants, monoamine oxidase inhibitors) should be avoided in favour of the least toxic (i.e. selective serotonin reuptake inhibitors) (AMH, 2018).

International research has reported a large degree of off-label prescribing for antidepressants. A 10-year study comparing antidepressant use across 40 countries in Asia found almost 40% of antidepressant prescriptions were for indications other than depression (Chee et al., 2015). Likewise, a recent descriptive study from Canada reported that approximately one third of antidepressants prescribed between 2003 and 2015 by primary care physicians were for off-label indications (Wong et al., 2017). A recent multinational study compared antidepressant use specifically in older adults between six jurisdictions in US, Canada, UK and Taiwan and found wide variation in the prevalence of antidepressant use between countries but the most common treatment indication in all countries was chronic pain (Tamblyn et al., 2019).

There are limited data available that provide an underlying rationale for the highly prevalent use of antidepressant use in elderly Australians. The PBS is Australia's government funded medicine subsidies scheme and is the most reliable and objective source of pharmaceutical data for the Australian population; however, a major limitation with any study that uses PBS data is that there is no information on indications for the medicines dispensed. Instead information has come from ecological analyses. One such study used self-reported rates of anxiety and depression reported in the 2007 National Survey of Health and Wellbeing and compared antidepressant dispensing as per PBS records in a representative sample of Australians of all ages and found poor alignment between the two (Hollingworth et al., 2010). Researchers suggested this mismatch was likely to represent a significant degree of off-label prescribing. Further information related to indications for antidepressants has been provided by a study utilising the Bettering the Evaluations and Care of Health (BEACH) survey, which collects information about prescriptions provided by a nationally representative sample of general practitioners (GP). Analysis of BEACH data between 2000 and 2010 indicated that 70% of all antidepressant prescribing by GPs was for depression, 16% for anxiety, sleep and other psychological disorders; and 10% for musculoskeletal problems, neurological problems and pain (Henderson et al., 2010). It is unknown to what extent these proportions reflect antidepressant prescribing from all practitioners in older adults.

The aims of the present study were to contrast individual administrative records with self-reported mental health symptoms and medicine use to provide a real world snapshot of antidepressant use in a population-based sample of older Australians and to examine the relationship between antidepressant use and symptoms of common mental disorders. We additionally aim to examine other factors associated with off-label prescribing of antidepressants, including pain, insomnia and suicidality; as well as correlations of specific antidepressant medication classes with suicidality.

Section snippets

The personality and total health through life (PATH) project

The PATH project, being undertaken by the Centre for Mental Health Research on Ageing, Health and Wellbeing at the Australian National University, was established in 1999 with the aim of longitudinally profiling a broad range of fixed and time-varying risk factors and moderators associated with physical, mental and cognitive health. PATH is based on three birth cohorts (1975–1979, 1956–1960 and 1937–1941); these analyses focused on data from the third wave of the older (60+) cohort conducted

Included participants

There were 1275 participants included in the final analysis (see Fig. 1 for Flowchart). Table 1 shows the sample characteristics and symptoms. Sex was relatively equally represented (quota sampling was conducted at baseline to ensure equal representation initially) and participants ranged from 68–74 years of age. One hundred and forty-six (11.5%) participants were dispensed an antidepressant within 40 days of the interview.

Self-reported antidepressant use

Of the 146 respondents on an antidepressant at time of the interview,

Discussion

This study provides a snapshot of current symptoms reported by a sample of older age concessional beneficiaries using antidepressants. Overall, we found that antidepressant use in the sample was higher than national average, with 11.5% using antidepressants in the PATH older adult sample compared to 9% of all adults nationally. This is consistent with the analysis by the Australian Commission on Safety and Quality in Healthcare that reported that in 2013–2014 the use of antidepressants in

Conclusion

Antidepressant use was elevated in this population-based sample of older Australian adults. Factors associated with use included female gender, presence of depression or anxiety, and pain. Approximately two-thirds of those prescribed antidepressants reported using them for depression or anxiety, with a minority using them for pain or sleep and 20% not reporting use. Findings highlight the need for careful prescribing and review of antidepressant medications in older adults, and the importance

CRediT authorship contribution statement

K.M. Chitty: Conceptualization, Formal analysis, Writing - original draft. P. Butterworth: Funding acquisition, Data curation, Writing - review & editing. P.J. Batterham: Conceptualization, Methodology, Supervision, Writing - review & editing.

Declaration of Competing Interest

Authors have no conflicts of interest to declare.

Acknowledgements

We thank the study participants, PATH Interviewers, Trish Jacomb, and Karen Maxwell. We would also like to acknowledge the contribution of Kaarin Anstey, Helen Christensen, Andrew Mackinnon and Simon Easteal.

Funding

This project was funded by an Australian National Health and Medical Research Council (NHMRC) Project Grant (NHMRC; Grant number: 418039). An NHMRC Early Career Fellowship funds KC (Grant number: 1122362). An NHMRC Career Development Fellowship funds PJB (Grant number: 1083311). The funding organization played no part in the design and conduct of the study; collection, management, analysis, and interpretation of the data; nor in the preparation, review, approval or decision to submit the

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