Recent trends in the use of antidepressant drugs in Australia,
Peter McManus, Andrea Mant, Philip B Mitchell
William S Montgomery,
John Marley and Merran E Auland
MJA 2000; 173: 458-461
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Objective: To determine the pattern of use of
antidepressant drugs in the Australian community, 1990-1998, and to
compare this with those of other developed countries.|
Design: Retrospective analyses of prescription and
sales data, together with information about patient encounters for
depression (from an ongoing survey of service provision by general
practitioners) and population-based prevalence estimates for
affective disorders (from community health surveys).
Main outcome measures: National and international
consumption of antidepressants, expressed in defined daily doses
(DDDs) per 1000 population per day. Changes in both the frequency of
general practice patient encounters for depression and
population-based prevalence estimates for affective
Results: Dispensing of antidepressant prescriptions
through community pharmacies in Australia increased from an
estimated 12.4 DDDs/1000 population per day in 1990 (5.1 million
prescriptions) to 35.7 DDDs/1000 population/day in 1998 (8.2
million prescriptions). There has been a rapid market uptake of the
selective serotonin reuptake inhibitors (SSRIs), accompanied by a
decrease of only 25% in the use of tricyclic antidepressants (TCAs).
In 1998, the level of antidepressant use in Australia was similar to
that of the United States, while the rate of increase in use between
1993 and 1998 was second only to that of Sweden. In Australia,
depression has risen from the tenth most common problem managed in
general practice in 1990-91 to the fourth in 1998-99, and the number of
people reporting depression in the National Health Surveys (1995 v
1989-90) has almost doubled. Of the prescriptions dispensed in 1998
for antidepressant drugs subsidised by the Pharmaceutical Benefits
Scheme, 85% were written by general practitioners, and 11.2% by
Conclusions: As in most developed countries,
antidepressant use increased between 1990 and 1998. The rapid market
uptake of the new antidepressants, particularly SSRIs, is likely to
have been driven by increased awareness of depression, together with
availability and promotion of new therapies.
The World Health Organization report on the global burden of disease
placed major depression fourth among the leading causes of disease
burden in the developing world in 1990, and predicted that it would
rise to second by the year 2020.1 In parallel with the
increasing awareness of depression as an important health issue, the
past decade has seen an increase in the pharmacotherapy options for
managing depression with the arrival of several new classes of
To review trends in antidepressant use in Australia, the Drug
Utilisation Sub-Committee (DUSC) of the Pharmaceutical Benefits
Advisory Committee, Department of Health and Aged Care, convened a
working group in 1998. The working group, which comprised
representatives from the DUSC and from the Australian
Pharmaceutical Manufacturers Association (APMA), reviewed
Australian and international data on antidepressant sales and
dispensing. The aim was to determine patterns of antidepressant use
in Australia between 1990 and 1998 and to compare Australian patterns
with those in similar developed countries. To assist in
interpretation of Australian drug use trends, the group reviewed
changes in both the frequency of general practice patient encounters
for depression and in population-based prevalence estimates for
Prescription and sales data
Prescription dispensing data were obtained from the
database maintained by the DUSC that monitors the dispensing of
prescription medicines through community pharmacies in
Australia.2 No data on public hospital
use are included in this database. The measurement units used are
either prescription volumes or the number of defined daily doses
(DDDs) per 1000 population per day. The DDD is based on the assumed
average daily dose of the drug when used for its main indication by
adults. It is the unit approved by the World Health Organization (WHO)
for drug use studies, and allows for comparisons independent of
differences in price, preparation and quantity per
prescription.3 Within the data on
dispensing of antidepressant drugs subsidised by the
Pharmaceutical Benefits Scheme (PBS), it is also possible to
determine the major specialty of the prescribing doctor.
Data on total sales of antidepressants from wholesalers to retail and
hospital pharmacies for all countries, except Sweden, were obtained
from IMS Health Incorporated. IMS Health is the leading
international provider of information on drug usage to the
pharmaceutical and healthcare industries.4 Data were retrieved as
kilograms of active ingredient and then converted to DDDs per 1000
population per day. Excluded were the use of lithium,
Hypericum (St John's wort) or tryptophan, and combinations
involving these drugs or their active constituents. Utilisation
data for Sweden, where separate local arrangements apply, were
supplied by the Swedish Association of the Pharmaceutical Industry
The 1999 WHO defined daily doses (DDDs) were used in calculations.
Drugs unique to particular markets that did not have DDDs available
were provisionally assigned values using standard references and
information provided by drug information centres in the countries
Information related to general practice patient encounters for
depression was obtained from the General Practice Statistics and
Classification Unit of the Family Medicine Research Centre (FMRC),
University of Sydney, which is conducting an ongoing survey of
service provision by general practitioners (GPs).6 This involves
1000 randomly selected, active, recognised GPs per year, each
recording details of 100 consecutive consultations on structured
encounter forms. Rolling recruitment ensures that the recording
weeks are distributed evenly over the year and that there is constant
change in participants. These data can be compared with the findings
of an earlier FMRC study of morbidity and treatment in general
practice that used simpler but compatible methods.7 Information on
prescribing by specialists is not included in these GP surveys.
Community health surveys
The 1995 National Health Survey was a household survey conducted by
the Australian Bureau of Statistics to obtain national benchmark
information on a range of health-related issues and to enable the
monitoring of trends in health over time.8 A previous health survey,
collecting broadly comparable data, was conducted in
The 1997 National Survey of Mental Health and Wellbeing of Adults was
also conducted by the Australian Bureau of Statistics and used a
representative sample of people aged 18 years or over living in
private dwellings.10 The survey was
interview-based with a diagnostic component administered through a
modified version of the WHO Composite International Diagnostic
Interview (CIDI). The CIDI translates the criteria of the
Diagnostic and statistical manual of mental disorders, 4th
edition (DSM-IV),11 and the International
classification of diseases, 10th edition (ICD-10),12 into sets of
questions that can be readily answered by the general adult
population. Specific combinations of symptoms may indicate a
specific mental disorder.
Antidepressant use in Australia
The dispensing of prescriptions for antidepressants through
community pharmacies in Australia increased from an estimated 12.4
DDDs/1000 population per day in 1990 (5.1 million prescriptions) to
35.7 DDDs/1000 population per day in 1998 (8.2 million
prescriptions). Trends in the use of the selective serotonin
reuptake inhibitors (SSRIs), tricyclic antidepressants (TCAs),
moclobemide, venlafaxine and nefazodone between 1990 and 1998 are
shown in Box 1.
The market uptake of the SSRIs has been rapid and accompanied by a
decrease of only 25% in the use of the TCAs. Other new agents included
moclobemide (a reversible monoamine oxidase type A inhibitor),
nefazodone (a 5-HT2 antagonist) and venlafaxine (a
serotonin-noradrenaline reuptake inhibitor).
The 10 most commonly dispensed antidepressants in Australia in 1998
were, in descending order, sertraline, dothiepin, paroxetine,
amitriptyline, fluoxetine, doxepin, moclobemide, imipramine,
venlafaxine and citalopram. Of these, only the four tricyclic
antidepressants were on the market in 1990, with dothiepin alone
maintaining or improving its position over this period.
Of the PBS-subsidised prescriptions dispensed for antidepressants
in 1998, 85% were written by GPs, while 11.2% were written by
We compared retail and hospital sales of antidepressants in
Australia and seven major developed countries for the years 1993 and
1998 (Box 2). In 1998, sales of antidepressants in Australia (34.2
DDDs/1000 population per day) were similar to those of the United
States (34.2 DDDs/1000 population per day), less than in Sweden (37.1
DDDs/1000 population per day) and France (36 DDDs/1000 population
per day) and higher than in Canada (30.8 DDDs/1000 population per day)
and the United Kingdom (30.4 DDDs/1000 population per day). Germany
and Italy had considerably lower usage levels (12 and 9.9 DDDs/1000
population per day, respectively). The rate of increase in Australia
between 1993 and 1998 was second only to that of Sweden.
For these same countries in 1998, Box 3 shows the percentage split
(based on DDDs/1000 population per day) of the antidepressant market
by drug class. There was considerable variability in the percentage
that TCAs represented of overall antidepressant use, from a low level
of 11% in Sweden through to a high of 67% in Germany. Australia, Canada
and France had a similar profile, with TCAs representing about 20% of
Venlafaxine was marketed in all eight of the countries surveyed and
ranged between 1.5% and 5.2% of the total use. Mianserin had a low level
of use in most countries, except for France and Italy, where it
represented about 4% of antidepressant use. It was not available in
North America. Similarly, moclobemide had a low level of use in most
countries, except in Australia, where it represented 12% of the
Surveys conducted in 1990-91 and 1998-99 by the Family Medicine
Research Centre have shown the increasing prominence of depression
as a problem managed in general practice.6,7 In 1998-99, depression
ranked as the fourth most common general practice problem, compared
with the tenth in 1990-91. The rate of patient encounters involving
depression per 100 encounters has increased from 2.1 in 1990-91 to 3.5
in 1998-99. In 1998-99, compared with 1990-91, antidepressants were
more likely to be prescribed per every 100 encounters for depression
(58.4 prescriptions [95% CI, 56.1-60.8] v 52.3 prescriptions [95%
Comparisons with age and sex demographics for total general practice
encounters (women, 58.7%) suggest that female patients were
over-represented at encounters for depression.
The most frequent patient age group in encounters at which a tricyclic
antidepressant was prescribed was 45-64 years (38%), whereas for
encounters at which SSRIs were prescribed it was 25-44 years (43%).
Sex distribution was similar for both drug groups, with about a third
of the patients being men.
Depression was the most common problem for which TCAs and SSRIs were
prescribed in 1998-99, although the proportion of TCAs prescribed
for depression (48.8% [95% CI, 44.3%-53.3%]) was lower than that of
SSRIs (81.9% [95% CI, 79.7%- 84.1%]). Other specific problems
managed with TCAs were sleep disturbance (7%), anxiety (5%) and back
complaints (4.5%). For the SSRIs, these were anxiety (5.8%) and
phobia/compulsive disorder (1.7%).
When used for depressive disorders, TCAs had a prescribed daily dose
consistently lower than the WHO DDD. The prescribed daily doses and
DDDs for the most commonly dispensed TCAs were amitriptyline (mean,
59 mg; median, 50 mg; DDD, 75 mg), doxepin (mean, 61 mg; median, 50 mg;
DDD, 100 mg) and dothiepin (mean, 85 mg; median, 75 mg; DDD, 150 mg). The
prescribed daily doses for the most commonly dispensed SSRIs were
much closer to the DDD: fluoxetine (mean, 24 mg; median, 20 mg; DDD, 20
mg), paroxetine (mean, 23 mg; median, 20 mg; DDD, 20 mg) and sertraline
(mean, 72 mg; median, 50 mg; DDD, 50 mg).
Community health surveys
The 1997 National Mental Health and Wellbeing Profile of Adults
identified a 5.8% prevalence of affective disorders (depression,
5.1%; dysthymia, 1.1%) during the 12 months before the survey among
people aged 18 years or over.10 Women were more likely
than men to have experienced affective disorders (7.4% compared with
Although based on self-reports, household surveys conducted by the
Australian Bureau of Statistics in 1989-90 and 1995 identified
marked changes in the number of people reporting current or previous
depression. In the 1995 National Health Survey, 8.1 persons per 1000
population reported depression as a long term condition, compared
with 2.8 persons per 1000 in the 1989-90 survey. For depression as a
recent illness, 11.4 per 1000 population reported this in 1995,
compared with 5.8 per 1000 in 1989-90.8,9
The past decade has seen a remarkable change in the number of people
recognised with and managed for depression, in the range of drug
therapy options available, and in the volume of antidepressants
prescribed. Previously, depression had been reported as
under-recognised and undertreated.13-15
Prominent among the likely reasons for this change are increased
community awareness of depression as an important health issue, and
attempts, most notably through government and community campaigns,
to reduce the stigma of mental illness and the gaps in professional
expertise inhibiting adequate recognition and treatment of
Coincident with these campaigns, important treatment
recommendations were released in the United Kingdom in 1992 (the
Royal College of General Practitioners and the Royal College of
Psychiatrists) and, in the United States, in 1993 (Agency for Health
Care Policy and Research).13,18 In Australia, the
Psychotropic drug guidelines19 are the endorsed national
standard, and the National Health and Medical Research Council has
published clinical practice guidelines for managing depression in
The 1995 Australian National Health Survey showed that the number of
people reporting depression as a recent and/or long term condition
had nearly doubled compared with the earlier survey conducted in
1989-90. Such a change in the true underlying prevalence of disease is
unlikely over a relatively short period of time, and the increase is
far more likely to reflect a greater awareness of depression, with
patients being more comfortable about coming forward for help and
doctors, particularly in general practice, being more willing to
provide it. This increased awareness of depression by doctors and
patients, together with the availability and promotion of new drug
therapy options (between 1990 and 1998, five SSRIs have been approved
for PBS subsidy together with moclobemide, venlafaxine and
nefazodone), accounts for the rise from the tenth to the fourth most
common problem managed in general practice between 1990-91 and
1998-99. In 1998-99, encounters for depression were also more likely
to generate a prescription for an antidepressant.
This change is reflected in drug utilisation statistics. The market
uptake of the SSRIs has been rapid and, remarkably, accompanied by
only a relatively small decrease in the use of the TCAs. As a result, the
overall antidepressant market has expanded greatly, with
utilisation (as defined by DDDs/1000 population per day) being
nearly three times greater in 1998 than in 1990. Prescription rates,
however, have risen only 60% over that time, as the newer
antidepressants are more likely to be dosed closer to the DDD than the
older tricyclic antidepressants. TCAs are prescribed for sleep
disturbance in a small proportion (7%) of patients, which is not the
case for SSRIs.
Most developed countries have seen similar trends, with sales in
Australia consistent with US sales and slightly higher than those in
the UK. The percentage that the SSRIs represented of total
antidepressant use in Australia in 1998 was similar to that in the
The considerably lower levels of antidepressant use in Germany are
probably related to Germany's strong tradition of use of
complementary medicines (substantial use of Hypericum
preparations [St John's wort] were not included in the comparisons);
and the lower levels in Italy may be because, in 1994-98, SSRIs were not
reimbursed by the national health system in Italy, but were fully paid
for by the patient (Dr Alberto Vaccheri, Associate Professor,
Department of Pharmacology, University of Bologna, personal
communication, June 1999).
Although there are interesting differences between countries, the
rapid uptake of the new antidepressants is likely to have been driven
by increased awareness, together with the availability and
promotion of new therapies. The drug utilisation patterns,
supported by evidence from population and general practice surveys,
showed that there has been growth in the actual market rather than just
redistribution within the market. Public health benefits of this
major change in drug use (eg, reductions in suicide rates) are
anticipated in the long term, but measuring population-level
outcomes from changes will not be easy.
Other members of the Antidepressants Working Group who helped
prepare these data were the Australian Pharmaceutical
Manufacturers Association and the pharmaceutical industry (Susan
Alexander, Mark Bradley, Michelle Burke, Liz Campbell, Victoria
Croker, Marnie Firipis, Deborah Monk, Michael Ortiz, Ruth Stokes,
Drug Utilisation Sub-Committee secretariat (John Dudley).
General Practice Statistics and Classification Unit, Family
Medicine Research Centre, University of Sydney (Helena Britt and
Geoff Sayer, who conducted the analyses of the depression data from
Disclosure: Philip B Mitchell has been a member of
scientific advisory boards for Eli Lilly, SmithKline Beecham and
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(Received 5 May, accepted 31 Aug, 2000)
Drug Utilisation Sub-Committee, Department of Health and Aged Care,
Peter McManus, MMedSc, BPharm, Secretary.
South Eastern Sydney Area Health Service, Sydney, NSW.
Andrea Mant, MD, FRACGP, MA, Area Adviser, Quality Use of
Medicines; and Associate Professor, School of Community Medicine,
University of New South Wales, Sydney, NSW.
School of Psychiatry, University of New South Wales, NSW.
Philip B Mitchell, MD, FRANZCP, FRCPsych, Professor; and
Administrative Director, Mood Disorders Unit, Prince of Wales
Hospital, Sydney, NSW.
Health Economics and Outcomes Research, Eli Lilly Australia Pty Ltd,
William S Montgomery, BPharm, DipHospPharm,
GradCertHealthEcon, Health Outcomes Research Manager.
Department of General Practice, University of Adelaide, Adelaide,
John Marley, MD, MB ChB, Professor.
Health Economics and Pricing Department, SmithKline Beecham
(Australia) Pty Ltd, Melbourne, VIC.
Merran E Auland, PhD, Health Economist.
No reprints will be avaliable from the authors.
Correspondence: Mr P
McManus, Secretary, Drug Utilisation Sub-Committee, Mail Drop
Point 83, Department of Health and Aged Care, GPO Box 9848, Canberra,
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|Percentage split of antideprssant sales (based on defined|
daily doses per 1000 population per day) by drug class in
1998 (data for all countries, except Sweden, from IMS
Health; Swedish data from the Swedish Association of
the Pharmaceutical Industry). SSRI = selective serotonin
reuptake inhibitor. TCA = tricyclic antidepressant.
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