Common Mental Disorders Depression - New Zealand Doctor

Pharmacological therapies: issues for evidence-based practice
Antidepressants are not recommended for the treatment of mild non-melancholic
depression; secondary care evidence suggests that the benefits are unlikely to
outweigh the side effects. 418,419 However, antidepressants are effective in primary care
and are recommended as a good option for moderate or severe depression.
Kirsch and colleagues (2008) 417 have challenged the efficacy of antidepressants
for all but the most severe cases of depression. Although their data suggest that
antidepressant efficacy may be less than generally accepted, there was a superior
effect in the antidepressant group compared with placebo, albeit below the somewhat
arbitrary NICE criterion for clinical significance. 348 The studies pooled by Kirsch et al. 417
may have been too short to show an effect: their mean duration was around 6 weeks,
whereas one third of responders and one half of those who achieved remission in the
Sequenced Treatment Alternatives to Relieve Depression (STAR*D) trial took longer than
6 weeks to respond. 353 Furthermore, the GDT notes that many of the trials included in
the meta-analyses included volunteers rather than patients representative of a primary
care population. However, the meta-analysis does confirm the trend for antidepressant
effectiveness to increase with the severity of depression, if only because the placebo
effect is less pronounced in this group. 417
There appears to be no substantial difference in effectiveness between different types
of antidepressant, either in the acute stage of treatment or in maintaining remission,
nor is there evidence to support the selection of one second-generation antidepressant
over another for specific symptoms such as anxiety or melancholia. SSRIs are generally
better tolerated than other types of antidepressant and are therefore appropriate as a
first-line choice of antidepressant. 65
The GDT notes that while it is reasonable to expect some improvement within 2 weeks,
response (50% or greater decrease in symptom severity) may take up to 4–6 weeks
and remission usually takes longer. Therefore it is important to ensure an adequate
dose and duration of treatment. 65 A substantial number of patients who do not achieve
remission within 6 weeks will do so if they continue taking the same drug, 353 even if the
dosage is not increased. 354
There is very strong evidence, largely from secondary care, that maintenance treatment
with an antidepressant for up to 36 months after remission reduces the risk of relapse.
The desirable length of therapy for an individual patient will depend on their risk of
relapse and on how tolerable they find the antidepressant. 354
There are risks associated with the use of antidepressants in pregnancy (see Chapter 7:
Special Issues: Women with Mental Disorders in the Antenatal and Postnatal Period).
As pregnancy may not be confirmed until it is relatively well-advanced, it is important
that women with depression who are of child-bearing age are aware of these risks (and
of the risks of untreated depression). Women with depression should be encouraged to
discuss pregnancy plans with their practitioner. 101
88
Identification of Common Mental Disorders and Management of Depression in Primary Care