British Journal of Clinical Pharmacology
© 2005 Blackwell Publishing Ltd
Br J Clin Pharmacol
and Children’s Health, Dunedin
School of Medicine, University of
Otago, PO Box 913, Dunedin,
64 34740999 Ext 8226
Department of Women’s
9 January 2005
11 May 2005
Suicide and self-harm following prescription of SSRIs and
other antidepressants: confounding by indication
Rebecca C. Didham,
Research Unit, Dunedin School of Medicine, University of Otago, Dunedin, New Zealand and
Otago, Dunedin, New Zealand
Doug W. McConnell,
Hayden J. Blair
& David M. Reith
Dunedin School of Medicine, University of
To identify the incidence and risk of suicide and self harm, among patients prescribed
A retrospective cohort study, with nested case control, of patients identified from a
nonrandom sample of general practices in New Zealand from 1996 to 2001. A total
of 57 361 patients who received a prescription for a single antidepressant were
identified from the RNZCGP Research Unit Database. Suicides within 120 days of a
prescription were identified from the New Zealand National Mortality Database and
self-harm events within 120 days of a prescription were identified from the New
Zealand Hospital discharge database.
26 suicides and 330 episodes of self-harm were identified within 120 days of an
antidepressant prescription. On univariate analysis the association, expressed as OR
(95% CI), between selective serotonin reuptake inhibitors (SSRIs) and self harm and
suicide were 2.26 (1.27–4.76) and 1.92 (0.77–4.83), respectively. When corrected
for the confounding effects of age, gender and depression/suicidal ideation there was
an association between SSRIs and self harm, OR 1.66 (95% CI 1.23–2.23), but not
for suicide, 1.28 (0.38–4.35). Paroxetine was a significant risk factor for suicide on
univariate analysis, 4.23 (1.19–14.95), but not when corrected for age, gender and
depression/suicidal ideation, 2.76 (0.30–24.87).
Age, gender and pre-existing depression/suicidal ideation are important confounders
in observational studies of the association between antidepressants and suicide or
Concerns have been raised about the potential for selec-
tive serotonin re-uptake inhibitors (SSRIs) to increase
suicidal ideation . In New Zealand the most widely
prescribed antidepressant is paroxetine, with fluoxetine
being the second most commonly prescribed antidepres-
sant . GlaxoSmithKline (GSK), the manufacturers of
Aropax (paroxetine) conducted trials in paediatric and
adolescent patients and found an increased risk of
adverse effects, including treatment emergent suicidal
ideation, but not completed suicide . This has resulted
in warnings against ‘off-label’ prescribing of paroxetine
to patients under the age of 18 as well as a caution issued
for close monitoring of both adults and paediatric
Suicide and self-harm following antidepressants
Br J Clin Pharmacol
present study did not compare either SSRIs or TCAs
with placebo or no treatment.
Overall the results of this study suggest that the more
depressed patients are prescribed SSRIs, therefore these
drugs appear to show a greater risk of self-harm and
suicide. However the real risk factors are more likely to
be depression and suicidal ideation. The effects of anti-
depressant medication upon completed suicide should
be further explored using RCTs, and using self harm as
a surrogate outcome measure.
We wish to thank the participating general practices
from the RNZCGPRU database for contributing their
records and allowing them to be used for research pur-
poses. We also thank Brendan Ward for designing the
computer programming for the case control analysis
and Ken Harrison for his work on previous analyses.
Funding: The Royal New Zealand College of General
Practitioners Research Unit receives financial support
from the New Zealand Government.
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