Common Mental Disorders Depression - New Zealand Doctor

Chapter 6 Management of depression in adults/pakeke
this approach is promising, though as yet there is no relevant evidence from a primary
care setting.
Secondary care evidence supports the use of combined psychological and
antidepressant therapy, particularly for people with more severe depression. 65
Pharmacological therapies
Primary care evidence
A systematic review 392 of 10 RCTs evaluated the efficacy and tolerability of SSRIs and
TCAs among patients with depressive disorders or subthreshold depression in primary
care. Both SSRIs and TCAs were more effective than placebo, with pooled estimates
showing a relative benefit of 1.24 (95% CI 1.11 – 1.38) for improvement with TCAs
and 1.30 (95% CI 1.15 – 1.46) for SSRIs. The review calculated the overall number of
patients who would need to be treated in order to benefit (or harm) one patient. The
number needed to treat for TCAs ranged from 7 to 16, and for SSRIs it was 7 to 9.
The numbers needed to harm (for withdrawal due to side effects) ranged from 4 to 30
for TCAs and 20 to 90 for SSRIs (Arroll, B 2007 pers. comm.). Medium dose (75–100
mg), as well as high-dose TCAs were effective; 56% to 60% of patients responded
to active treatment compared with 42% to 47% for placebo (Arroll, B 2007 pers.
comm.). Most of the studies were small, of limited quality and industry-funded, and
the review authors note the possibility of publication bias, whereby studies showing
positive results for the intervention are more likely to be published than studies with
inconclusive or negative results.
The NICE (2004) 65 guideline included 13 studies of antidepressants set in primary
care 393-404 all of which compared the efficacy of different antidepressants. Three studies
also included a placebo arm. 396,401,403 SSRIs were relatively well-tolerated and of
equivalent efficacy to alternatives, such as the TCA amitryptyline, and also venlafaxine,
that are generally less well-tolerated. 65
A recent health technology assessment by the Agency for Healthcare Research and
Quality (AHRQ) evaluated the comparative effectiveness of second-generation
antidepressants (see Box 6.5). 351 This review drew a distinction between trials of
efficacy and of effectiveness. Efficacy trials were defined as those conducted in
carefully-selected populations under carefully-controlled conditions, while effectiveness
trials were those designed to have greater generalisability to typical practice. Only
seven trials (of 187 considered) met the AHRQ criteria for effectiveness and were
considered to have good applicability to primary care populations. 336,405-411 A further
180 studies were also included in the AHRQ (2007) review, 351 of which 139 were
RCTs. For treatment of major depression, there were no substantial differences in
effectiveness among second-generation antidepressants. This conclusion was based
on direct evidence from three effectiveness studies, 405-407 as well as indirect evidence
from efficacy trials.
Identification of Common Mental Disorders and Management of Depression in Primary Care 85